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Passive Solar: The Beauty of Light

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Does Passive Solar Design Still Make Sense?

Our ‘green’ building adventure began in 2013 when I came across various Passive House and high performance projects in Prefabulous + Almost Off the Grid by Sheri Koones. The red house featured on the cover and built by GO Logic, in particular, seemed like a striking departure from conventional homebuilding as practiced in the US.

In its overall shape it echoed an earlier project that I only became aware of later, the Smith House in Illinois by Katrin Klingenberg.

Arguably, in both cases, these homes have too much glass on their south elevations, both in terms of potential overheating of the interior and in purely aesthetic visual terms. Nevertheless, using south-facing glazing to bring in the sun during the winter months while getting some Btu’s of free heat made a lot of sense to us, especially in a heating dominated climate like ours here in the Chicago area.

By the time construction began, we had settled on what seemed like a significant amount of windows and a kitchen door for our south elevation. We felt the layout would be an appropriate amount both in terms of passive solar heating and aesthetics, in addition to daylighting needs.

Moreover, by addressing the main weaknesses of the original Passive Solar movement of the 1970’s, namely the lack of air tightness and sufficient levels of insulation, we hoped that we could strike a balance between enjoying the seasonal movement of the sun in and out of our home while mostly eliminating the risk of overheating, even during shoulder seasons (spring and fall).

Since our build, however, there appears to be growing concern about just how effective this design strategy really is for Passive Houses or high-performance homes more generally. In effect, are the potential savings on a heating bill really worth the risk of temporarily overheating interior spaces?

Joe Lstiburek, of Building Science Corporation fame, puts it bluntly when quoted in a GBA article regarding the use of high SHGC glass:

“Don’t bother with the passive solar. Your house will overheat in the winter. Yes, you heard that right. Even in Chicago. … You should go with very, very low SHGCs, around 0.2, in your glazing. If this sounds familiar to those of you who are as old as me, it should.

“We were here in the late 1970s when ‘mass and glass’ took on ‘superinsulated.’ Superinsulated won,” Lstiburek continued. “And superinsulated won with lousy windows compared to what we have today. What are you folks thinking? Today’s ‘ultra-efficient’ crushes the old ‘superinsulated,’ and you want to collect solar energy? Leave that to the PV.”

Clearly, he’s not entirely wrong, especially when some of the early failures in the Passive House movement revolved around this very issue of overheating. If you were an early adopter of the Passive House concept, especially if you were the homeowner, and you ended up with comfort issues because of too much glass on your southern facade it certainly would make you doubt the purported precision of the Passive House energy modeling.

Nevertheless, with careful planning, it is possible to avoid this issue of overheating while still getting to enjoy most of the benefits associated with passive solar design. In our case, this meant limiting windows on the north side (net energy losers) to just our daughter’s bedroom, while glazing on the east side shows up only in a small area of our front door.

Small amount of glass in our front door offering some daylighting benefit for our entry area.

In addition, we avoided any potential for overheating from our west-facing windows by using self-tinting Suntuitive glass in our master bedroom and family room. This glass can fluctuate in its SHGC between (.08 – .18) depending on whether in its fully tinted or clear state (varies depending on surface temperature of the glass).

West facade with self-tinting Suntuitive glass.

With the other three sides of the house accounted for, we were able to concentrate all of our attention on the best window layout for the south side of the house. The utility room, which is on the southeast corner of the house, only really needed a small window, so we went with a single 3′ x 5′ unit. In the kitchen, the window above the sink was already going to be limited because of the lower cabinets, and was mainly for a view while doing dishes. This unit ended up being 4′ x 5′. For the kitchen door we went with a mostly glazed door with privacy glass, which has worked out well as it lets in an abundant amount of daylight while it’s never caused any issues with overheating.

The real challenge was getting the family room window on the south side of the house sized correctly. The temptation was to go too large since we had the space to do it. Instead, we wanted to retain some empty wall space for artwork on either side of this window, while also remembering that even the best window is still a lousy wall (e.g. R-40 wall vs. R-6 window).

In the end, we decided to go with a 3′ x 9′ window in our family room, slightly smaller* than the units on the west facade with Suntuitive.

{*7-27-20 Correction: I messed this up. The dimensions weren’t different between the south-facing family room window and the west-facing windows with Suntuitive — it was a height off the floor change. For the south-facing family room window we went slightly higher, 32″ off the finished floor, in order to gain a little more privacy, while on the west-facing windows we maintained a lower height of 27″ off the finished floor to maximize our views out and into our backyard. This 5″ difference may not sound like much, but it has a dramatic effect in terms of overall views and perspective when standing at these windows.}

In terms of wall area on our south facade, the windows and kitchen door account for just under 15% of the total, so not a crazy amount, and obviously nowhere near the amount of glass in a curtain wall.

The Sun’s Path Month-to-Month

For those who haven’t directly experienced a space that utilizes passive solar design principles, it may be helpful to see in photos what exactly this effect means month-to-month in a real home.

In our case, we have a long interior wall that runs east-west along the longest axis of our home. This wall effectively separates the private areas to the north (bedrooms and bathrooms) from the public areas to the south (family room, kitchen, and utility room). For context, this long wall stands almost 16 feet from all of the south-facing windows.

In our kitchen and family room, here’s what the sun looks like near midday in January:

jan fmly rm
Sun in January, slowly moving away from the back wall (at right) that runs east-west along the longest axis of the house.
jan ldry rm
Sun pouring into the utility room in January.

By the middle of February, the sun is already making its way towards the windows, barely able to reach the family room couch, while it still adds plenty of sunshine and warmth to the kitchen and family room areas:

sun feb fam
Sun in mid-February.

By the Spring equinox, the sun has continued its slow march across the family room floor towards the south-facing windows:

sun mar fam
Sun in March.

In the basement, with the help of two large south-facing windows (each 4′ x 4′) and our oversized window wells, the sun is making the same progression as it brightens up the below grade space:

sun mar base
Basement in mid-March.

Although we chose to forego any windows on the east side of our house, mainly for privacy and energy loss reasons, the small amount of glass in our front door still allows our entry area to be bathed in beautiful early morning light without contributing a significant amount of heat gain:

sun mar morning east
East-facing entry area flooded with morning light from the minimal glazing in the front door.

The seasonal path of the sun can also be marked on the exterior by its progress up or down the facade of our south elevation. By mid-March you can see the shadow line formed by our substantial roof overhang beginning to make its way down the siding — at this point, just above the windows and kitchen door. This invisible ‘curtain’ will cover the glass in the windows entirely by the end of June, completely denying the heat of the sun direct entry into the structure.

sun ext mar
South elevation in mid-March. Note the shadow line just above the windows and kitchen door.

Even in April the sun is mostly denied entry; reduced to a sliver of light hitting the wood floor in the family room:

sun apr fam
Family room in April.

In June, by the time of the summer solstice, the sun has been pushed outside completely, limited to the metal sill pans on the exterior of the windows.

Our south elevation during the rough framing stage. Layout from left to right: family room, kitchen door, kitchen window, and utility room.

With significant and thoughtfully placed windows on the south side (combined with a substantial roof overhang), we’re able to enjoy views to the outdoors year-round, allowing us to maintain an unbroken connection to nature in our yard, without any of the heat or glare normally associated with the summer sun. It also means we don’t need to bother with curtains or other window treatments, or the hassle of managing when they should be opened or closed.

Also, since the transition from winter (welcoming the sun in) to summer (denying the sun entry) has proven to be seamless, we’ve been able to avoid installing any curtains or window treatments in order to hide from any periods of unwanted sunlight. Basically, this invisible ‘curtain’ effect of passive solar design means we enjoy all the benefits of window treatments without any of the hassles (routine opening and closing, cleaning, or maintenance and repair), all while maintaining an unobstructed view of the outdoors. This is especially rewarding during the long winter months when starved for sunlight and extra warmth, but equally pleasurable as life begins to hum in the yard with the return of spring and summer.

In the photo below, the family room window (at left) and the kitchen door are protected from the heat of the sun by the roof overhang. The window on the back wall (facing west) is protected by self-tinting Suntuitive glass, which also allows us to enjoy unimpeded views of our backyard without the need for curtains or window treatments, even on the sunniest and hottest days of summer.

sun june fam
Family room in June with no direct sun allowed entry into the space.

On the exterior, by the middle of June, this shadow ‘curtain’ has fallen over the entire face of the south-facing windows, denying the sun entry into the home where it could cause unpleasant glare and unwanted heat gain (these windows have a SHGC of .54), which would needlessly increase cooling loads for our Mitsubishi heat pump system, while also reducing overall occupant comfort.

Around the summer solstice in June, this is what the set-up looks like outdoors:

Southwest corner of the house around the summer solstice.
A second view of this ‘curtain’ effect; this time from the southeast corner of the home.

This effect is also visible from the interior while looking out the south-facing windows. With a substantial roof overhang the sun can barely reach the metal sill pans by the middle of June:

sun june util
Utility room window in the middle of June. Note the sun hitting the outside edge of the metal sill pan.

In June, the sun is able to get slightly deeper inside the home in the basement — in this case managing to hit the surface of the window stool or sill.

sun base june

Even in the heart of the summer, the sun is still denied direct access to the interior spaces on the main floor:

sun july fam
Family room in July. The sun remains outside.

A second look at the metal sill pan from the utility room window, this time in July:

sun july util

After slowly making its way back into the south-facing living areas, by November the sun is once again approaching the back wall in the family room and kitchen:

sun nov family
Family room by mid-November.

Even though the utility room window is a relatively modest size (3′ x 5′), it provides ample daylight and plenty of warm sunshine over the course of our long winter months:

sun utility nov
Sunlight spilling out of the utility room by mid-November.

Here’s another view of the sun exiting the utility room on its way to the back wall in the main living area:

sun utility nov 2
Sun in mid-November.
sun nov kitch
Sun hitting the kitchen countertops in November, bathing the space in a warm glow.

By late December, around the winter solstice, the sun is finally able to hit the back wall in the main living area, maximizing the amount of direct sunlight that enters the house:

sun dec family mbr
Sun during the winter solstice, at the doorway to the master bedroom.

sun kit dec
In late December, the sun hits the back wall where the family room meets the kitchen.

sun dec utility barn door
Sunlight from the utility room window hitting the barn door in the main living area.

Even in the basement, where it’s more difficult for the sun to make its way into the space, with our oversized window wells and two large windows the sun manages to get very close to the center of the space just in front of the structural beam. This light pouring in helps keep us connected to the outdoors, mostly eliminating the cave-like feel normally associated with many below grade spaces. Even on the coldest days in winter, this daylighting effect makes the basement a warm, inviting space.

basement bfws sun
Sunlight entering the basement in mid-December.

Some Final Thoughts

We were expecting to enjoy the seasonal movement of the sun, watching it progress in and out of the main living space, warming us in the winter while also helping to moderate summertime AC demand. One unanticipated surprise, however, is how effective our window layout has been in maintaining a high level of daylighting, even on the grayest of overcast days.

Short of a menacing thunderstorm that turns the skies gray-black, we almost never have to turn on lights during the day. For instance, in the photo below it has snowed overnight, and the skies are an unrelenting blanket of gray. Nevertheless, because daylight has ample means for entering the living space, no artificial light is necessary. Note, too, in the background, how clear the Suntuitive glass is when not in its fully tinted state.

The kitchen door, because it consists mostly of privacy glass, contributes a great deal to this daylighting effect — both in summer and winter — and we’re extremely happy we didn’t choose a more opaque door style.

Another side benefit in this regard is how the porch light outside this glass-filled door also acts as a de facto night light for the kitchen — its soft, but effective, glow makes it easy to navigate around the space in the middle of the night without having to turn on any interior lights.

cloudy day still light
Even on a cold, gray winter day the windows allow in a great deal of daylight, dramatically improving the overall livability of the space while allowing us to keep the lights turned off.

One final, unanticipated surprise is how much the house is flooded with light on cloudless nights when there’s a full moon. The moonlight creates a soft, beautiful source of light as it falls across these interior spaces.

In terms of shoulder seasons, when sunlight still has some access to the interior but outdoor temperatures are mild or even occasionally warm, we haven’t really noticed a problem. In spring, if outdoor temps should reach the 70’s during the day it is frankly welcomed with open arms, as we’re starved for warm sunshine at winter’s end. In the fall, if there’s an occasional too warm day, we simply open a couple of windows. So far we’ve never had to turn on the AC in October, for instance.

If there’s any failure in our set-up, it would be the family room couch. From the end of December until the end of January, if it’s a sunny day, regardless of how cold it gets outside, sitting on the couch is uncomfortable, if not impossible. Sitting in shorts and a tank top would be the only way to make it remotely comfortable.

Thankfully, we’re almost never on the couch during this time, so it’s never been a problem for us. Having said that, if this family room were dedicated office space and I needed to be sitting at my desk from 10am-2pm, it would be extremely uncomfortable. This is a good example of how carefully not just an overall floor plan needs to be designed, but how even individual spaces need special attention, in particular for year-round HVAC comfort based on how occupants are actually going to be using the space.

Overall, we’ve been very pleased with the layout of our windows and their ability, in conjunction with the roof overhang to the south, to allow in ample amounts of sunlight during the colder months while still being able to keep it out on the hottest days of the year. With detailed planning, our experience suggests that designing living spaces for a real passive solar benefit is still a worthwhile goal.

Although it may be safer to ignore this design strategy altogether in the hottest climates (simply designing to keep the sun outside year-round may be the better option, which would include the use of low SHGC glass as Lstiburek recommends), passive solar has proven to be a great source of enjoyment for us, particularly during our winters here in Chicago, which tend to release their grip too slowly and ever so begrudgingly.

If given the chance, we would definitely design our house again with these passive solar techniques in mind.

Completing our Wall Assembly: Rockwool Batts, Intello, and Drywall

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Insulation for Exterior Walls

Once Wojtek and Mark were done installing our continuous insulation on the exterior side of our Zip sheathing (4″ of Rockwool Comfortboard 80), including the first layer of battens (no more errant fasteners through the Zip to worry about), I was able to move inside and begin installing Rockwool Batts (R-23) in our 2×6 wall framing.

Once we had moved on from our first builder, and after reading up on the available options for insulation, we decided to invest in Rockwool insulation, both the rigid Comfortboard 80 on the exterior of our sheathing and the Rockwool batts for inside our stud bays. Although more expensive, particularly the Comfortboard 80 for continuous insulation (used rigid foam would’ve been substantially less expensive), we felt that many of its properties made it worth the added cost.

In particular, by helping our wall assembly to be vapor-permeable (or vapor open), we felt the Rockwool could help mitigate any mistakes, should they be made, in the wall assembly details. This being our first build acting as a GC, we wanted to add some margin for error wherever we could find it.

More details on our wall assembly and how we finalized details, including our desire to maintain a high level of IAQ, can be found here: Wall Assembly

For environmental reasons, one of our goals was to try and be as “foam free” as possible throughout the build. In addition, beyond just this issue regarding the use of foam (in all its forms: rigid board and sprayed varieties alike), there’s increasing awareness about the carbon footprint of our structures, not to mention the total carbon footprint of our daily lives.

At any rate, if I had it to do over, I would at least seriously consider using reclaimed rigid foam for our continuous insulation over the sheathing (both for the potential cost savings and its status as a reclaimed material otherwise headed for a landfill), understanding that it does reduce a wall’s ability to dry to the exterior. As others have noted, using reclaimed rigid foam in this way may be the best, or “greenest”, use of foam insulation until the construction industry hopefully moves beyond its use altogether as better options become more viable (e.g. wood fiber insulation).

Here are some resources for reclaimed rigid foam:

http://insulationdepot.com/

https://www.reuseaction.com/sales/foam/

https://www.greeninsulationgroup.com/

https://www.repurposedmaterialsinc.com/polyiso-insulation/

I would also consider using dense pack cellulose in the 2×6 walls instead of the Rockwool batts if I could find an installer I was reasonably certain could do the work properly. During construction it felt safer to use my own labor to install the Rockwool batts, thus avoiding the possibility of any gaps in the wall insulation. I was hoping to offset the cost of the batts with my free labor, plus I just enjoyed doing the work. Had we gone with the dense pack cellulose, it would’ve been something I couldn’t do on my own (no equipment or training).

lights on in base 4 rockwool
Basement ready for Rockwool batt insulation.

Installing the Rockwool batts is fairly easy and satisfying work. They’re much easier to work with than fiberglass batts, which are horrible on your skin and tend to flop around as you try to get them into place. While the Rockwool also produces some irritating fibers when it’s cut (and requires a dust mask like fiberglass), I found that a shower easily washed them away. Wearing long sleeves during installation also easily mitigates this issue.

base knee wall w: rockwool going in
Insulating the exterior wall in what will be the basement stairwell.

Also, the fact that the Rockwool batts have a friction fit means they don’t require any additional staples or netting to get them to stay put once installed.

Because of the friction fit, it’s also easy to tear off small pieces to stuff into irregular shaped voids should the need arise.

rim joist w: and w:out rockwool
Basement rim joist without and with Rockwool batt insulation.

Like the Comfortboard 80, the batts can have some variation from one piece to another, with a change in the amount of density clearly visible. With the Comfortboard 80, this was significant enough that we avoided using the worst pieces, meaning those with the least amount of density (these pieces felt thinner and sometimes even crumbly). Although this inconsistency was still present in the batts, I managed to use almost every piece, saving the least dense pieces for use in some interior walls for sound attenuation (more on this topic below).

base kneel wall corner rockwool
Corner of basement with knee wall and rim joists insulated with Rockwool batts.

Overall, we were happy with the Rockwool batts, and would definitely use them again should dense pack cellulose not be a viable option. They’re also ideal for a self-build since anyone who’s reasonably handy can install them should they have the time available during construction.

rockwool around base beam
Rockwool batts packed into gaps around the basement steel beam.

In conjunction with the Intello that would eventually be installed over the 2×6 framing members and the Rockwool batts, we also used Flame Tech putty pads to air seal behind every outlet and light switch box. I had seen them used in a Matt Risinger video for sound attenuation:

The other option would’ve been to use airtight junction boxes. Here are a couple of examples: Small Planet Supply and 475HPBS.

In order to limit issues with all the air sealing I was doing, I tried to stick with products my subcontractors already used everyday. As a result, since my electrician wasn’t familiar with airtight junction boxes, I opted instead to come in after he had everything installed and apply the putty pads. I found installing them to be straightforward and pretty quick.

box label putty pads

The putty pads are attached to release paper. Once the paper was removed the pads were easy to mold around each outlet and light switch box.

label putty pad
Acoustical putty pads purchased on Amazon.

Here’s a completed outlet box:

putty pad on outlet
Putty pad molded around every outlet and light switch in exterior walls.

The trickiest area to detail for the walls was at the ceiling and wall junction. In our case, the roof trusses sit on 2-2×6’s turned on their sides, which sit on top of the wall’s double top plate. The 2-2×6’s create space for our service cavity under the bottom chord of the roof trusses.

extoseal-encors-as-gasket
2-2×6’s on edge, sitting on double top plates. Extoseal Encors acting as gasket once taped from the exterior face of the Zip sheathing over the top of the 2-2×6’s, thus completing an air sealed connection between the exterior (Zip sheathing) and the interior before roof trusses are set in place. More details here: Roof Details

Before cellulose could be blown into the attic, we installed Intello to the bottom chord of the roof trusses. At all outside edges the Intello was carried from the roof trusses down over the double top plates of the walls, anticipating the Intello eventually being installed on the walls, which required a connection point between the Intello on the ceiling and the Intello on the walls.

ceiling-wall b4 Intello - Rockwool
Ceiling and wall areas before installing Intello on the bottom chord of the roof trusses and Rockwool batts in the walls.

After the Intello was installed on the ceiling, a service cavity (or service core, or service chase) was created with 2×6’s screwed to the bottom chord of the trusses through the Intello.

string between junction boxes to make sure they're straight
Service cavity with 2×6’s attached to trusses through the Intello. More info on the service cavity here: Ceiling Details.

This gap was going to be a dedicated space for lighting and the 3″ Zehnder tubes of our ERV (as things turned out, we didn’t end up needing this space for the Zehnder tubes).

bare trusses - intello - intello w: single layer CB 80 - service chase
Intello coming down from the roof trusses to cover the double top plates on the wall.

Before installing the Rockwool batts in the walls, I was also able to fill this gap created by the two 2×6’s on their side that sit on top of the double top plates with leftover pieces of Comfortboard 80. The first piece of Rockwool fit snug inside the gap, while the second piece was attached to the first with some plastic cap nails and the friction supplied by the 2×6’s forming the service cavity. Some additional holding power was added at the gable ends by utilizing drywall clips (visible in the photo below):

intello onto top plates
Connecting Intello to top plates with a strip of Tescon Vana tape, creating a clean and solid surface for the eventual Intello on the walls.

The drywall clips were helpful in lending support to drywall anywhere that adding solid blocking would be time consuming or a physical challenge.

nailer for ceiling drywall
These drywall clips worked great in places where the sheetrock needed additional support.

Even though we utilized a 12″ raised heel roof truss, and we had 4″ of Rockwool on the exterior of our Zip sheathing, it was important to fill this gap created by the service cavity to make sure our thermal layer was unbroken around the perimeter of the house (4″ Rockwool on the exterior, 5 1/2″ Rockwool in the stud bays). The outside edge of the roof truss is also the most vulnerable to ice damming, so having the 4″ of Rockwool Comfortboard 80 directly below this area where blown-in cellulose would be installed offers some additional thermal performance to the attic insulation.

Another view of this area where roof truss meets the 2-2×6’s standing on their side, creating a gap between the bottom chord of the roof truss and the top plates on the wall below.

sealed top of wall from inside
Roof truss on 2-2×6’s turned on their sides, which have been sealed with Pro Clima tapes. HF sealant completes the airtight connection between the Zip sheathing and the 2-2×6’s.

If I had it to do over, I would go with a 24″ raised heel truss, as this would offer not only significantly more R-value in this area (for relatively little expense), it would also make any inspection or repairs in this area much easier to deal with.

mbr w: rockwool in walls
Installing Rockwool batts in the walls of the Master Bedroom.

As each piece of Rockwool batt was installed, it was important to keep any butt joints between cut pieces tight together. Also, once each piece was snug inside the stud bay I finished by gently fluffing the outside perimeter edges so the Rockwool sat as flush as possible to the 2×6 studs, thus maximizing their R-value.

mbr rockwool complete
Master Bedroom ready for Intello on the walls before drywall gets installed.
family rm w: rockwool
Family room ready for Intello and then drywall.

Intello

With 4″ of Rockwool Comfortboard 80 on the exterior of our sheathing, the code specifies that we could’ve just used latex paint as our interior vapor retarder (Class III).

Again, to improve our margin for error, I felt like it was worth the added expense and time to install a smart vapor retarder (CertainTeed’s Membrain product would’ve been another alternative) to avoid potential issues with diffusion in the winter.

When I asked a question on GBA about this issue, the consensus seemed to be that the Intello, although technically unnecessary, was a nice bit of insurance.

It also added a final layer to all of the previous air sealing details. With redundant layers of air sealing, even if small areas experience failure over time, there are still other areas to back it up, thus maintaining our overall air tightness for the long term.

intello at frt dr basement
Intello installed in the basement stairwell by the front door.
finishing intello mbr
Intello in Master Bedroom nearly complete.

Sealing the Intello to the subfloor was one of the final air sealing chores of the build. It was deeply gratifying to finally get to this point, especially since drywall and then flooring were up next.

tescon on intello at subfloor
Intello taped to the subfloor with Tescon Vana tape.
intello tvana complete mbr
Intello complete in the Master Bedroom.

Thoughts on Advanced Framing Techniques

If I had it to do over, I would use less framing around windows and doors, along with using pocket headers instead of the more traditional insulated headers we ended up with. Pushing the header to the exterior sheathing would mean being able to insulate the pocket on the interior side with Rockwool or dense pack cellulose, rather than the rigid foam we ended up with (unfortunately, XPS in our case).

family rm w: rockwool
Family room ready for Intello.

Before we had to fire them, the two GC’s we were still working with as framing began were unfamiliar with advanced framing techniques, and they were already struggling to comprehend the many Passive House details in the drawings (not to mention many of the conventional details) so, as I’ve noted elsewhere, I had to pick my battles carefully.

Another change I would make would be at points where interior walls meet up with exterior walls. Rather than using ladder blocking to make the connection, which is still better than more traditional methods (creating a boxed in void that’s virtually impossible to insulate), I would utilize a metal plate at the top of the walls to make a solid connection. In addition to making drywall installation easier since it would create space between the two intersecting walls for sheets of drywall to be passed through, it would also make installing insulation, especially batt insulation, much more straightforward with clear and easy access (no horizontal blocking to get in the way).

intello at ladder
Intello at partition wall that meets the exterior wall (using ladder blocking).

A ProTradeCraft article discusses what builder David Joyce believes is ‘worth doing’ in terms of advanced framing techniques. Perhaps just as important, he points out what he believes can be safely ignored, or is just ‘not worth doing’ when it comes to OVE.

In this Matt Risinger video, architect Steve Baczek delves into some of the key components he uses to optimize advanced framing techniques:

In addition to the pocket headers, the idea of using header hangers instead of additional jack studs, seems to make a lot of sense.

And here’s a ProTradeCraft video regarding their own take on Advanced Framing:

One final change to our framing would be opting for 2-stud corners instead of the California 3-stud corners that we have. Although a relatively small change, I think a 2-stud corner is cleaner and allows for slightly more insulation in this vulnerable area.

Clearly each designer, architect, GC, or framing crew will have their own particular views on advanced framing, so there’s room to make individual choices without undermining the goal of balancing structural integrity with reduced energy demand. Local codes, along with the opinion of your rough framing inspector, will also have to be accounted for.

My guess is these techniques will continue to evolve, especially if specific products come to market to aid the process (i.e. reduce the amount of framing lumber required while ideally also lowering labor costs, all without negatively affecting the overall strength of the structure).

intello kitchen
Intello in the kitchen complete.

One final attempt at some additional air sealing was around outlet and switch boxes as they met up with the Intello. With a bead of HF Sealant, it was easy to make an airtight connection between the Intello and the box.

cu intello at outlet
Completing connections around outlet and switch boxes with HF Sealant.

At doors and windows, I finished these areas off with a strip of Tescon Vana tape, just as I had at the top and bottom of the walls.

intello complete br2
Completing Intello around a bedroom window.

Because corners tend to be problematic in terms of air leakage, I also added a dab of HF Sealant to these areas for the sake of some added redundancy.

lwr lft corn wdw w: intello & tape
Lower left corner of window with some added HF Sealant in the corner.
upper rgt corner wdw w: intello
Upper right corner of a window just before final piece of Tescon Vana tape is run across the top of the window frame, tying together the Intello and the light blue Profil tape that is air sealing around the window.

Sound Attenuation

Since we designed our home with a smaller than average footprint, incorporating many Not So Big House principles (roughly 1500 square feet for the main floor, with another 1500 square feet in the full basement below), one way to make the floorplan feel larger than it actually is was to provide some sound attenuation in key areas (we incorporated several other techniques to “expand” the feel of the floorplan that will be discussed in upcoming posts regarding interior design).

For instance, we installed the Rockwool in the long partition wall that runs east-west down the center of the floorplan. This wall helps define the barrier between public areas (kitchen and family room) on the south side of the home and the private areas (bathrooms and bedrooms) on the north side of the home.

We could’ve used Rockwool Safe ‘n’ Sound, but at the time, during construction in the fall of 2017, it was a special order item in my area, whereas the batts were already in stock, both for my main 2×6 partition wall, a 2×6 plumbing wall, and the remaining 2×4 walls that we felt could benefit from the Rockwool.

In the photo below, the Rockwool in the main east-west partition wall is covering the refrigerant and drain line for one of our three Mitsubishi heat pump heads, along with the usual electrical conduit for outlets and light switches.

rockwool 2nd br entry hall
Rockwool added to some interior walls for sound absorption, thus reducing unwanted sound transmission between certain spaces.

Here’s another view of this partition wall, this time from the opposite side inside the second bedroom:

rockwool 2nd br interior side
Same section of east-west partition wall from inside the second bedroom.

We also added Rockwool to the wall that connects the master bath to the 2nd bedroom bath, and between the 2nd bath and 2nd bedroom. The Rockwool was even added to the wall between our kitchen and utility room, where we have our washer and dryer, in the hopes that it would limit the amount of noise coming from the machines (which it thankfully has).

rockwool bath walls
Rockwool in bathroom wall around main waste stack.

Although this doesn’t make for a totally sound proof connection between spaces (we weren’t prepared to take things that far — roughly equivalent to air sealing a Passive House in the amount of detail required), the ability of the Rockwool to significantly muffle sound between rooms is quite impressive and, for us at least, well worth the effort and added expense.

rockwool kitch - utility
Rockwool in the wall between the kitchen and utility room.

For instance, while standing in the master bathroom, should someone be running water or flushing the toilet in the 2nd bathroom directly on the other side of the wall, the majority of the sound that reaches your ear comes by way of the master bedroom doorway, not through the wall directly. Out of curiosity I tested this idea with music playing on a portable stereo in the 2nd bathroom with the same results — sound through the wall is dramatically muffled, while the same sound that easily travels out of the bathroom and makes it way via the bedroom doorway is crystal clear. With the door to the 2nd bathroom and our master bedroom door closed, this same sound is obviously further reduced.

It’s also nice to watch TV in the family room and know that as long as the volume is at a reasonable level you’re not disturbing anyone trying to sleep or read in the two bedrooms. This kind of sound attenuation also adds a level of privacy to the bathrooms while they’re in use.

And, again, it’s not that no sound is transmitted from one room to another, rather it’s almost entirely limited to doorways, thus significantly reducing the overall impact of the noise that is transmitted. In other words, our goal was rather modest, we were just after significant sound absorption, not sound proofing (e.g. the level of noise cancellation required in a professional recording studio or a high-end home theater room).

As a result, I would definitely use Rockwool for sound absorption again. In fact, I can’t imagine going without this kind of sound attenuation (or something akin to it using other products or techniques outlined in the videos above) now that we’ve been able to enjoy it in our new home. It effectively prevents the issues often associated with so-called “paper thin” walls.

Arguably, addressing this issue of unwanted sound transmission is even more important in Passive Houses or high-performance homes that are already much quieter than conventional homes because of the extensive air sealing and well above code levels of insulation. In our own case, outside noises either disappear entirely or are significantly muffled — this includes a commuter train a couple of blocks away.

As a result, any noises within the home itself become much more pronounced since they don’t have to compete with the typical noises coming from outside the home. For instance, when we first moved in the fridge in the kitchen was easily the most obvious, consistent sound in the house. After a couple of weeks it just became background noise we’ve grown to ignore, but it was surprising just how loud it was initially, especially our first few nights in the home when everything else was so quiet.

In addition to excessive air leakage and obvious temperature swings between rooms, along with poorly sized or placed window layouts, the lack of any sound attenuation between rooms is one of the issues we notice the most when we’re inside more conventionally built homes. Much like all of the conveniences associated with a modern kitchen, it’s easy to take something like effective sound attenuation for granted until you’re required to go without it (e.g. in the case of kitchens while on a camping trip or waiting for a kitchen to be remodeled).

With all of the Rockwool batts in place, and the Intello installed over the exterior walls, drywall could finally go up.

Drywall

We went with USG 5/8″ EcoSmart drywall (GBA article on EcoSmart). We chose the 5/8″ over 1/2″ mainly for added durability and some slight sound deadening between rooms.

I had read about Certainteed’s AirRenew drywall, but it sounded like the only VOC it absorbed was formaldehyde, which, if I understand the issue correctly, can be safely avoided with the use of appropriate cabinets and furniture. If memory serves, AirRenew works by utilizing a compound similar to triclosan, meaning a biocide, which some believe can have potentially serious health effects. It’s not clear to me, even now, whether the use of AirRenew drywall makes sense, or exactly what compound (or series of compounds) are utilized to absorb the formaldehyde since Certainteed has remained silent on this point, claiming the information is proprietary. Nevertheless, it has a Declare label, so ILFI must believe it’s reasonably safe to have on painted ceilings and walls.

At any rate, we wouldn’t be bringing in any new furniture that would have elevated levels of VOC’s (including flame retardants) once construction was complete. Since our last house was significantly larger, roughly 2,800 sq. ft., it was fairly easy to downsize, donating or giving away what we couldn’t use in our new house, while holding on to our favorite and most useful pieces. It also helped that we never really filled up our last house (e.g. we never got around to purchasing a formal dining room set), so we didn’t have as much “stuff” to discard as we might have.

Moreover, by being mindful of every finish we create or use (primers, paints, wood flooring, grout sealer, caulks and sealants, kitchen cabinets etc.), along with any other products we might bring into the new house (e.g. surface cleaners, new furniture, fabrics, even perfumes and colognes, etc.), we’re hoping to maintain a high level of IAQ.

The International Living Future Institutes’s Red List and their database of Declare products were a big help to us, even though we’re not pursuing any kind of certification with them. The Greenguard certified label was also helpful, in particular when it came time to choose tile and grout.

By consciously choosing every product and material that comes into the home, it’s possible to at least reduce our exposure to harmful VOC’s and chemicals. While still imperfect (Who can you trust?), these kinds of programs do allow designers and homeowners to take some control over the environments they’re creating and living in, which is empowering to a degree. Far better if the US regulatory bodies operated under a precautionary principle model when it came to industrial products.

Frankly, in a rational system, one that was truly looking out for the best interests of consumers, this kind of research — time consuming and frustrating busy work to put a finer point on it — would be considered laughable if not horrifying. In a rational system it would be safe to assume that any product for sale, apart from some careful instructions on their use and disposal, would be safe to have inside your home without having to worry about short or long term health implications.

Nevertheless, if unintended health consequences are to be avoided during a renovation or a new construction build, consumers have little choice but to do the necessary homework (or pay someone else to do it for them) and be as thoughtful as possible with their selection of materials.

drywall family rm
Kitchen and family room after drywall was installed. Ready for primer, paint, and flooring.

Now that all of the elements of our wall assembly were complete, it was time to have some fun with final finishes: flooring, wall colors, wood trim, doors, kitchen cabinets…

 

Siding Part 1: Continuous Insulation with a Rainscreen

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Continuous Insulation vs. Double-Stud Wall

Although builders can make either approach to high-performance walls work, we decided continuous insulation (or CI for short) made the most sense to us. And while continuous insulation has its own challenges, especially in terms of air and water sealing details around windows and doors, intuitively we felt insulation on the outside of our sheathing would give us our best chance at long-term durability for the structure.

In spite of the fact that these kind of wall assemblies are climate specific, for anyone interested in the performance of various wall assembly approaches this BSC paper is an excellent place to start:

High R-Walls

Or you can check out Hammer and Hand’s evolving wall assembly strategies here:

Passive House Lessons

And here’s a mock-up wall assembly by Hammer and Hand showing many of the details we incorporated into our own house:

While many believe a double stud wall simplifies much of the framing, we decided that a continuous insulation approach, which in theory should better manage seasonal moisture changes inside the walls while it also eliminates thermal bridges, was worth the extra effort.

2 Layers of Rockwool over Zip Sheathing

Based on the drawings from our original builder, Evolutionary Home Builders, who was going to use 3.75″ inches of rigid foam, and the recommendations of both PHIUS and Green Building Advisor for our climate zone 5 location (leaning heavily towards PH performance), we decided to go with 4″ of Rockwool Comfortboard 80 on top of our Zip Sheathing.

For more information regarding how we came up with the specifics of our wall assembly, go here:

Wall Assembly

Finding Subcontractors for a Passive House

In the Chicagoland area it’s still a struggle to find builders or subcontractors who are knowledgable about, or even interested in, “green building”. In fact, despite our well-documented experience with Evolutionary Home Builders, clients continue to hire Brandon Weiss (Dvele and Sonnen) and Eric Barton (apparently now on his own as Biltmore Homes, or Biltmore ICF) presumably because the options here in Chicago remain so limited. We assume this is the case because we still get the occasional email from current or former clients who have also had a negative experience working with Brandon or Eric. In addition, even though PHIUS has dozens of certified builders and consultants listed for Illinois and the larger Midwest region, it’s unclear just how many of them have worked directly on an actual Passive House project.

Until there’s more demand from consumers, or the building codes change significantly, it’s difficult to imagine the situation improving much in the near future. This is unfortunate since particularly here in the Chicago area, or the Midwest more broadly, homes could really benefit from the Passive House model, or something close to it, e.g. The Pretty Good House concept, because of our weather extremes (dry, cold winters and hot, humid summers). The combination of meticulous air sealing, high R-values, and continuous ventilation associated with any high-performance build is hard to beat in terms of day-to-day occupant comfort, not to mention the significant reduction in both overall energy demand and the cost of utilities.

In our own case, when I think of all the individual trades we had to hire, securing a siding contractor was far and away the most difficult. Our HVAC contractor for the ductless mini-splits was already somewhat familiar with “green” building and PH, so working with me on air sealing details and dealing with a thick wall assembly didn’t worry him. Also, if I had it to do over, I don’t think I’d bring up all the PH details with a plumbing or electrical contractor when getting bids since the air sealing details are pretty straightforward and can easily be planned for and executed on-site after they begin their work (assuming someone else, most likely a rough carpenter, GC, or homeowner is tasked with all the air sealing chores). And if the concrete sub is unfamiliar with insulation under a basement slab, or over the exterior walls of the foundation, then it’s easy enough for framers, or even homeowners if necessary, to do this work, along with installing a vapor barrier like Stego Wrap before the basement slab gets poured.

For siding, however, because of the level of detail involved before the siding itself could be installed, it was a real challenge to even get quotes. As things turned out, we had nearly twenty contractors (a mix of dedicated siding contractors and carpenters) visit the job site before we received an actual estimate. Many of those who visited the job site expressed genuine interest, most going so far as to acknowledge that this kind of wall assembly made sense and would probably be mandated by the residential code at some point in the future, but almost without exception they would disappear after leaving the job site — no bid forthcoming, and no response to my follow-up phone calls or emails.

Clearly they were terrified, not without justification, to tackle something so new, viewing our project through a lens of risk rather than as an opportunity to learn something new. From their point of view, why not stick with the type of jobs they’ve successfully completed hundreds of times in the past? It also didn’t help that I was a first time homeowner/GC, rather than a GC with a long track record of previously built homes in the area.

In addition, not only is continuous insulation over sheathing a novel concept in the Chicago area, especially in residential builds, even utilizing a ventilated rainscreen gap behind siding is almost unheard of — typically Hardieplank lap siding is installed directly over Tyvek or similar housewrap (this can be observed directly on hundreds of job sites across the city and suburbs). And this isn’t entirely the fault of contractors. For instance, how many homeowners when presented with the idea of continuous insulation, or a rain screen gap, balk at the extra costs associated with these techniques without carefully considering the potential energy savings or increased durability for the structure?

While there are any number of certified LEED projects in our area, and even some Passive House projects (both residential and commercial) in Chicago and the surrounding suburbs, for the most part consumers are still largely unaware of Passive House or other “green” building standards like Living Building Challenge. Clearly “green” building, let alone Passive House, has its work cut out for it here in the Midwest if it ever hopes to have a meaningful impact on the construction industry.

Installing Rockwool over the Zip Sheathing

Mike Conners, from Kenwood Passivhaus, was nice enough to recommend Siding and Window Group, which definitely got us out of a jam. Thankfully, Greg, the owner, was up for the challenge and was nice enough to let us work with two of his best guys, Wojtek and Mark.

Initially Wojtek and Mark dropped off some of their equipment at the site the day before they were to start work on the house. This gave me a chance to go through many of the details with them directly for the first time. Although a little apprehensive, they were also curious, asking a lot of questions as they tried to picture how all the elements of the assembly would come together. In addition to the construction drawings, the series of videos from Hammer and Hand regarding their Madrona Passive House project were incredibly helpful (this project in particular was a big Building Science inspiration for us).

Also, this video from Pro Trade Craft helped to answer some of the “How do you…?” questions that came up during the design and build phases:

As sophisticated and intricate as some architectural drawings may be, in my experience nothing beats a good job site demonstration video that shows how some newfangled product or process should be properly installed or executed.

On the first day, while Wojtek and Mark installed the Z-flashing between the Zip sheathing and the foundation, along with head flashings above the windows and doors, I started putting up the first pieces of Rockwool over the Zip sheathing.

installing head flashing above wdw
We found it easier to embed the metal flashings in a bead of Prosoco’s Fast Flash. Once in position, an additional bead of Fast Flash went over the face of the flashing, ensuring a water tight connection between the metal and the Zip sheathing.

For the first layer of Rockwool we installed the pieces horizontally between studs as much as we could, knowing that the second layer of Rockwool would be oriented vertically. This alternating pattern helps to ensure seams are overlapped between layers so there aren’t any areas where the seams line up, an outcome that could undermine the thermal performance of the 2 layers of Rockwool.

z flashing nw corner
Z-flashing carried down over the exposed face of the Rockwool on the outside of the foundation walls — once installed, the gravel is pushed back so it covers the area where the flashing terminates on the face of the Rockwool. The other 3 sides of the house had much less exposure in this foundation-gravel border connection.

We didn’t worry too much about the orange plastic cap nails missing studs since they were sized to mostly end up in the Zip sheathing. In the end only a couple of them made it completely through the Zip without hitting a stud.

1st pcs rockwool going up n side
Putting up the first pieces of Rockwool on the north side.

Every so often Wojtek would come around the corner and watch what I was doing before asking questions about specific elements in the wall assembly.

orange cap nails for 1st layer rockwool
Plastic cap nails we used to attach the first layer of Rockwool. I purchased these from a local roofing supply house.

By the time I had about a quarter of the north side covered, Wojtek and Mark were ready to take over from me.

1st layer rockwool n side
First layer of Rockwool mostly complete on the north side. Before installing the bottom row of Rockwool we used shims to create a slight gap between the Rockwool and the metal Z-flashing on the foundation insulation to allow any water that ever reached the green Zip sheathing a clear pathway out.

In a pattern that would repeat itself with each layer of the remaining wall assembly, Wojtek and Mark would carefully think through the details as they progressed slowly at first, asking questions as issues arose, before getting the feel for what they were doing and eventually picking up speed as they progressed around each side of the house.

20171002_081038
Outside corner showing the Z-flashing covering the face of the Rockwool on the foundation with the first layer of Rockwool covering the Zip sheathing above.

Working through the many details with Wojtek and Mark — the majority of which occur at junctions like windows and doors, the top and bottom of the walls, along with mainly outside corners — was both collaborative and deeply gratifying. They demonstrated not only curiosity and an ability to problem solve on the fly, they also clearly wanted to do things right, both for me as a customer and for the house as a completed structure (it felt like both aesthetically and in building science terms).

1st layer rockwool at wdw buck
First layer of Rockwool meeting up with a plywood window buck. We tried to keep connections like these as tight as possible, especially since the window buck itself already represents a slight thermal bridge.

They never hurried over specific problem areas, arrogantly suggesting they knew better, instead they patiently considered unanticipated consequences, potential long-term issues, and actively questioned my assumptions in a positive way that tried to make the overall quality of the installation better. This mixture of curiosity, intelligence, and craftsmanship was a real pleasure to observe and work with.

starting 2nd layer rockwool n side
Mark and Wojtek beginning the second layer of Rockwool on the north side.

If a GC built this level of rapport with each subcontractor, I can certainly understand their refusal to work with anyone outside of their core team — it just makes life so much easier, and it makes being on the job site a lot more fun.

2nd layer rockwool at utilities
Second layer of Rockwool installed around mechanicals. Note the sill cock, or hose bibb: although it runs into the house, we left it loose so that it could be adjusted until the siding was complete — only then was it permanently soldered into place.
weaving outside corner w: 2nd layer
Weaving the seams at the outside corners to avoid undermining the thermal performance of the Rockwool.
2nd layer rockwool fastener at wdw
Close-up of the fasteners we used to attach the second layer of Rockwool.

For the second layer of Rockwool, Wojtek and Mark tried to hit only studs with the black Trufast screws. In fact, screwing into the studs with these fasteners, in effect, became a guide for accurately hitting studs with the first layer of strapping.

plates for 2nd layer rockwool

These Trufast screws and plates worked well and were easy for Wojtek and Mark to install.

trufast screw bucket
inside bucket trufast screws
The Trufast screws and plates were purchased from a local roofing supply house.
w side 2 layers rockwool
West side of the house with 2 layers of Rockwool complete.
1st layer rockwool into s side garage
First layer of Rockwool filling the gap between the house and garage framing.

If our lot had been larger, we would’ve gone with a completely detached garage, but unfortunately it just wasn’t an option.

2nd layer rockwool closing gap at garage
Second layer of Rockwool closing the gap between house and garage completely, ensuring our thermal layer is unbroken around the perimeter of the house.
nw corner 2 layers rockwool
Northwest corner of the house with the 2 layers of Rockwool installed.

It was exciting to see the house finally wrapped in its 4″ of Rockwool insulation.

Installing Battens and Creating our Rainscreen

Initially we were going to use 2 layers of 1×4 furring strips (also referred to as strapping or battens); the first layer installed vertically, attaching directly over the 2×6 framing members through the 2 layers of Rockwool and the Zip sheathing, with the second layer installed horizontally, anticipating the charred cedar that would be oriented vertically on the house.

Pro Trade Craft has many really informative videos, including this one on using a rainscreen behind siding:

Nevertheless, as the second layer of Rockwool went up, Wojtek and Mark pointed out that putting the siding in the same plane as the Rockwool/metal flashing on the basement foundation would be needlessly tricky. In other words, maintaining about a 1/8″ horizontal gap between the bottom edge of the vertical siding and the metal flashing on the foundation around the house would be nearly impossible, and any variation might prove unsightly.

As a solution, we decided to use 2×4’s for the first layer of strapping. By adding to the overall thickness of the remaining wall assembly it meant the eventual siding — now pushed slightly out and farther away from the Z-flashing covering the face of the Rockwool on the foundation — could be lowered so that visually it slightly covered what would’ve been a gap between the top of the metal flashing on the foundation insulation and the bottom edge of the siding. Wojtek and Mark also found that the 2×4’s were easier to install than the 1×4 furring strips directly over the Rockwool so that it didn’t overly compress the insulation (an easy thing to do).

Unfortunately, increasing the overall wall thickness with 2×4’s meant having to use longer Fastenmaster Headlok screws (it would also cost us later when it came to the siding on the north side of the house — more on this later). Apart from this change, the additional overall wall thickness mostly just increased the air gap in our rainscreen, which arguably just increased potential air flow while also expanding the drainage plane behind the eventual siding.

In one of the Hammer and Hand videos Sam Hagerman mentions that at least 1.5″ of screw should be embedded into the framing (excluding the thickness of the sheathing) for this type of wall assembly, but when I asked a Fastenmaster engineer about this directly he recommended a full 2″ of their screws should be embedded into the framing members in order to avoid any significant deflection over time.

As a result, we ended up using 8.5″ Headlok screws. The screws work incredibly well, requiring no pre-drilling, and they’re fun to use with an impact driver (keep your battery charger nearby). Along with the plastic cap nails and Trufast screws, I think we ended up with less than a dozen fasteners that missed the mark for the entire house — a testament to Wojtek and Mark’s skill. I was able to seal around these errant fasteners from the inside with a dab of HF Sealant.

headlok missed framing
Sealing around a Headlok screw that missed a 2×6 framing member.

During the design stage, using these longer screws prompted concerns regarding deflection, but based on this GBA article, data provided by Fastenmaster, along with some fun on-site testing, the lattice network of strapping (whether all 1×4’s or our mix of 2×4’s and 1×4’s) proved to be incredibly strong, especially when the siding material is going to be relatively light tongue and groove cedar.

For the garage, since insulation wasn’t going to cover three of the walls (only the common wall with the house was treated as part of the house wall assembly), we used significantly shorter Headlok screws for the first layer of furring strips.

monkey on furring strips
The Beast testing out the structural integrity of our strapping on the garage. Note the Cor-A-Vent strip below the bottom horizontal furring stip, helping to establish a ventilated rainscreen.
garage only 2x4s
Common wall inside the garage. Only a single layer of strapping was necessary in preparation for drywall.

Mark took the time to recess these screws to make sure they didn’t interfere with the eventual drywall.

recess 4 screws
Recessed Headlok screw on a 2×4 in the garage. Ready for drywall.

A small detail, but one of many examples showing Wojtek and Mark’s attention to detail, not to mention their ability to properly assess a situation and act appropriately without having to be told what to do.

Once the 2×4’s were all installed vertically through the structural 2×6’s as our first layer of strapping, Wojtek and Mark could install the components of the rainscreen, including the Cor-A-Vent strips at the top and bottom of the walls, as well as above and below windows and doors. In combination with the 2×4’s and the 1×4’s, this system creates a drainage plane for any water that makes its way behind the siding, while also providing a space for significant air flow, speeding up the drying time for the siding when it does get wet.

rainscreen2.jpg
Why use a rainscreen? Illustration courtesy of Hammer and Hand.

In addition to the Cor-A-Vent strips, we also added window screening at the bottom of the walls just as added insurance against insects. We noticed that on the garage, even without any insulation, the Cor-A-Vent didn’t sit perfectly flat in some areas on the Zip sheathing. Since the Rockwool on the foundation, now covered by the metal flashing, was unlikely to be perfectly level, or otherwise true, along any stretch of wall, it made sense to us to double up our protection in this way against insects getting into the bottom of our walls at this juncture.

starting 1x4s n side
1×4’s being installed horizontally on the north side in preparation for the charred cedar that will be installed vertically. Also note the Cor-A-Vent strips just above the foundation and below the window.
cor-a-vent-product-label
The main product we used to establish our ventilated rainscreen.
insect screen for rscreen
Window screen we cut to size for added insurance at the bottom of the walls around the Cor-A-Vent strips.

Wojtek and Mark also did a nice job of taking their time to shim the 1×4 layer of furring strips, thus ensuring a flat installation of the charred cedar.

shims behind 1x4s
Shims behind some of the 1×4 furring strips to ensure a flat plane for the vertical cedar siding.

This really paid off, not only making their lives easier when installing the tongue and groove cedar, but also providing aesthetic benefits in the overall look of the siding. This was especially true on the north side of the house, which has the largest area of charred siding with almost no interruptions, apart from a single window. It’s also the tallest part of the house, so without proper shimming the outcome could’ve been really ugly. Instead, once the cedar siding was installed it was impossible to tell there was 4″ of Rockwool and 2 layers of strapping between it and the Zip sheathing.

Really impressive work by Wojtek and Mark.

lking down furring behind rscreen at fdn
Looking down behind the ventilated rainscreen — 2×4, 1×4, with Cor-A-Vent and window screen at the bottom, just above the top of the foundation. This gap behind the siding provides ample air flow for the cedar siding, ensuring that the wood never remains wet for long.
rscreen furring at foundation
Strapping and rainscreen elements around a penetration near the top of the foundation.

Things got somewhat complicated around windows and doors, but once we worked through all the details for one window it made the remaining windows and doors relatively straightforward to complete.

Below you can see all the elements coming together: the window itself, the window buck covered with tapes for air and water sealing, the over-insulation for the window frame, the Cor-A-Vent strip to establish air flow below the window and behind the eventual cedar siding, along with the strapping that both establishes the air gap for the rainscreen while also providing a nailing surface for the siding.

Once most of the siding was complete around each window, but before the 1×6 charred cedar pieces used to return the siding to the window frames were installed, each window received a dedicated metal sill pan. The pan slid underneath the bottom edge of the aluminum clad window frame and then extended out just past the edge of the finished siding (I’ll include photos showing this detail in the next blog post about installing the charred cedar siding).

Here’s a JLC article discussing a couple of options for trim details in a thicker wall assembly with similar “innie” or “in-between” windows:

Window Trim

And here’s a detailed slide presentation by Bronwyn Barry regarding details like these for a Passive House wall assembly:

Sills and Thresholds – Installation Details
wdw rscreen and frame detail
The many details coming together around a window. In addition, each window eventually received a dedicated metal sill pan as a durable way to ward off water intrusion.
from int wdw rscreen and sill
Looking through an open window to the sill and the rainscreen gap at the outside edge. Note the Extoseal Encors protecting the sill of our window buck.
lking down wdw rainscreen
Outside edge of the window sill, looking down into the mesh of the Cor-A-Vent strip with daylight still visible from below.
rscreen at hd flash on wdw
Head flashing at the top of a window with doubled up Cor-A-Vent strips above it.
out corner hd flshng ready for sd
Same area, but with a 1×4 nailed across the Cor-A-Vent, creating a nailing surface for the cedar siding.

Many of the same details were repeated at the top and bottom of our two doorways. Below is a close up of the kitchen door threshold with Extoseal Encors and Cor-A-Vent again, along with additional metal flashing. Once a dedicated metal sill pan was installed (after most of the siding was installed), it felt like we did everything we could to keep water out.

kitch dr prepped 4 sd
Many of the same air and water sealing elements and rainscreen details present around the windows ended up at the top and bottom of doors as well.

In the photo below, you can see the many elements we utilized to try and prevent moisture damage around the front porch. For the door buck itself, I applied Prosoco’s Joint and Seam, both at joints in the plywood and the plywood/Zip sheathing connection, but also between the concrete and the door buck, as well as between the Rockwool and the concrete. We also kept the 2×4’s off the concrete, while also using the Cor-A-Vent strips to establish a ventilated rainscreen so that any moisture that does get behind the siding has ample opportunity to dry out in this area before it can cause any rot.

frt porch prep - rscreen water
Front porch: elements in place to try and prevent moisture damage.
west w: 2 layers battens
West facade prepped for siding.
flashing details on porch
Wojtek and Mark did a nice job with all the metal flashing details around the house — these kind of areas are the unsung heroes of a structure that manages water safely, and unfortunately go largely unnoticed by most homeowners.

In the next blog post I’ll go through the details for the top of the ventilated rainscreen when discussing how the charred cedar siding was installed.

Mark and Wojteck at front door
Mark and Wojtek installing Cor-A-Vent above the front door.

Even without the siding installed yet, it was especially rewarding to see all the underlying prep work involved in finishing our thermal layer and rainscreen come together so nicely.

Mark and Wojtek on the roof
Mark and Wojtek on the garage roof finishing up the battens for the front of the house.

Many thanks to Wojtek and Mark for executing all these details with such skill!

Blower Door (Air Sealing #9 )

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When it was time to schedule our blower door test we considered using Eco Achievers, but we only knew about them because they’ve worked extensively on projects for our original builder, Evolutionary Home Builders. We decided the potential awkwardness, or even a possible conflict of interest, wasn’t worth pursuing their services. An example of guilt-by-association I suppose, one that is probably unfounded but, nevertheless, the strong affiliation with our original builder made it difficult for us to reach out to them for help. They also hired one of Brandon’s former employees (this employee was nothing but nice and professional towards us as we were deciding to part ways with Brandon), which would’ve only added another layer of awkwardness to the situation.

Unsure how to proceed, I looked online and found Anthony from Building Energy Experts. He was able to come out and do a blower door test for us, helping me hunt down a couple of small leaks, so that we ended up at 0.34 ACH@50 for this initial test.

Here’s a Hammer and Hand video discussing the use of a blower door:

On a side note: all of the Hammer and Hand videos, along with their Best Practices Manual, were incredibly helpful as we tried to figure out all the Passive House details related to our build. It’s no exaggeration to say that without Hammer and Hand, the Green Building Advisor website, BSC, and 475 HPBS, our build would’ve been impossible to accomplish on our own. I owe an incredible debt of gratitude to all of these great resources who invest valuable time sharing such a wealth of information.

Below is a Hammer and Hand video noting the importance of properly detailing corners to avoid air leaks:

Because of this video, I sealed all of my corners for the windows and doors like this:

HF Sealant in corners b4 blower door
Adding Pro Clima HF Sealant after completing taping of the corner, just for added insurance against potential air leakage.

I also added some HF Sealant to the lower portion of the windows, since some air leakage showed up in this area with Anthony where components of the window itself come together in a seam.

sealant on wdw components junction
Seam near bottom of window where components meet — sealed with HF Sealant.

The areas where components come together often need special attention.

close up corner and wdw components seam w: sealant
Close-up of this same area — seam in components sealed, along with the bottom corner of the window and the gap between window buck and window.

Even with layers of redundancy in place, in the picture below there was a small air leak still present at the bottom plate – sub flooring connection. A coating of HF Sealant easily blocked it.

Once the stud bays were insulated (after most of the siding was up), the interior walls would eventually be covered with Intello (I’ll cover the details in a future post on interior insulation), adding yet another layer of redundancy for mitigating potential air intrusion.

area of kitchen sill plate leakage
Area of kitchen sill plate leakage.

Anthony didn’t have any previous experience with a Passive House build, so it occurred to me that it might be beneficial to reach out to Floris from 475 High Performance Building Supply (he had already done our WUFI analysis for us), and Mike Conners from Kenwood Property Development to see if there was someone locally who did. Mike is a Passive House builder in Chicago who had already helped me out with some Rockwool insulation when we came up short earlier in our project (the two GC’s we fired repeatedly struggled with basic math), and he was very nice to take the time to answer some other technical questions for me as well.

Both, as it turned out, ended up recommending that I contact Steve Marchese from the Association for Energy Affordability.

Steve would eventually make three trips to the house, doing an initial blower door test after the structure was weather-tight and all the necessary penetrations had been made through our air barrier, a second test after exterior continuous insulation was installed, and a final test after drywall was up to ensure there hadn’t been any increase in air leakage during the final stages of construction.

Steve starting blower door test
Steve setting up the blower door for his first test.

Following Passive House principles for our build, we also followed the same protocols for the blower door tests: Blower Door Protocol

With the structure under pressure from the blower door fan, Steve and I walked around the house while he used a small smoke machine in order to try and find any leaks that I could then seal up.

Steve testing window gasket
Steve starting at the windows. Here testing a window gasket for air leakage.

The gaskets around our windows and doors proved to be some of the weakest areas in the house although, comparatively speaking, it was inconsequential since the overall air tightness of the structure was fairly robust (favorite word of architects).

Steve showing impact of unlocked window
Steve showing me the impact a window in the unlocked position can have on air tightness. The gasket, ordinarily squeezed in the locked position, works to bring the sash and the frame tightly together.
Steve smoke at family rm wdw
Looking for areas around the windows that might need adjusting or additional air sealing.

For instance, even though no substantial air leakage showed up around this kitchen door, during our first winter this same door eventually had ice form outside at the upper corner by the hinges, on the exposed surface of the gasket where the door meets the frame.

Steve at kitchen door

After figuring out how to adjust the door hinges, there was no longer any ice showing up this winter, not even during our Polar Vortex event in late January.

Much the same thing occurred around our front door as well, with the same solution — adjusting the hinges to get a tighter fit at the gasket between the door and the frame.

Steve testing attic hatch
Steve testing the attic hatch for any air leakage.

Steve was nice enough to go around and methodically check all the penetrations in the structure.

Steve testing plumbing vent in kitchen
Steve testing for air leaks around the kitchen plumbing vent and some conduit.
Steve testing for air leaks @ radon stack
Steve testing for air leaks around the radon stack.
Steve @ radon stack close up
Close-up of radon stack during smoke test.

There was one area in the guest bathroom where the Intello ended up getting slightly wrinkled in a corner during installation. With Tescon Vana and some HF Sealant I was able to address it so nothing, thankfully, showed up during the smoke test.

Steve testing wrinkled area of Intello
Steve testing area of Intello that I inadvertently wrinkled during its installation.

After looking around on the main floor, Steve moved down into the basement.

Steve testing for air leaks @ main panel
Checking for leaks at the main electrical panel.
Steve testing for air leaks @ main panel exit point
Checking for leaks at the conduit as it exits the structure.
Steve testing for air leak @ sump pit cap
Looking for air leakage around the sump pit lid.

The lids for the sump pit and the ejector pit were eventually sealed with duct seal putty and some Prosoco Air Dam.

Steve testing for air leaks @ ejector pit
Testing the ejector pit for air movement.
Steve testing for air leaks @ Zehnder exit point
Checking for air leakage around one of the Zehnder ComfoPipes as it exits the structure.
Steve testing for air leaks @ pvc:refrigerant lines
Looking for air leaks around the heat pump refrigerant lines as they exit the structure.
Steve smoke at sump discharge
Checking around the penetration for our sump pump discharge to the outside.

Before the second blower door test, I was able to add some duct seal putty to the lids of the sump and ejector pits.

ejector pump lid w: duct seal
Ejector pit lid with some duct seal putty.

Below is a copy of Steve’s blower door test results, showing the information you can expect to receive with such a report:

Final Blower Door Test Results

For the last two tests Steve used a smaller duct blaster fan in order to try and get a more precise reading for air leakage.

Steve at front door
With Steve just after the initial blower door test was complete.

Steve would be back two more times — once before drywall, and once after drywall — just to ensure we had no loss of air tightness develop in the interim stages of the build (especially after continuous exterior insulation with furring strips were installed).

Here are the final figures noting where we ended up:

0.20 ACH@50 and 106 cfm@50

We are well below Passive House requirements (both PHI and PHIUS), so there was a great sense of relief knowing that all the time and effort put into air sealing had paid off, giving us the tight shell we were looking for. Even so, it was still pretty exciting news, especially for a first build.

And here’s an interesting article by 475 HPBS regarding the debate over how air tightness is calculated for PHI vs. PHIUS projects, and the potential ramifications:

Not Airtight

HVAC Part 2: Ductless Mini Split

9

System Requirements

The plan for our house was to combine an HRV or an ERV (for a continuous supply of fresh air), with a ductless mini split air source heat pump system for our ventilation, heating, and air conditioning needs. Almost all of the projects I had read about utilized this same combination, especially here in the US.

The only real debate, apart from specific brand options, was whether or not to utilize only one distribution head on our main floor, as opposed to installing multiple heads for a more ‘dialed-in’ level of comfort (e.g. in the basement or the bedrooms).

Our original builder had in our construction drawings one head in the kitchen/family room and one in the basement, which was pretty standard for a Passive House level project. It was, therefore, pretty shocking to find out that our second builder (there were two partners) and their HVAC subcontractor were suggesting a system that was grossly oversized for our needs. You can read about the details here: GBA: Oversized System 

This was just one of many ‘red flags’ that convinced us to move on and GC the project ourselves. It’s also a reminder that old habits die hard, meaning even seasoned contractors, in any trade, need to be willing to learn new ideas and techniques if they want to truly be considered professionals and craftsmen — unfortunately, they’re the exception to the rule, at least in our experience.

One of the disappointments associated with our build is, in fact, the disinterest (in some cases even outright hectoring contempt) shown by various tradespeople in our area for ‘green’ building generally. Doubtless, at least a partial explanation for why much of the Midwest seems so far behind in adopting ‘green’ building techniques, especially when it comes to air sealing, insulation, and IAQ beyond code minimum standards. Hopefully this changes significantly in the coming years.

Consequently, I took Steve Knapp’s advice (from the comments section of my question) and contacted Home Energy Partners (their new name: HVAC Design Pros). Isaac responded quickly and eventually did our Manual J, confirming we needed a much smaller system, one that is more consistent with a Passive House project, or even just a high-performance build more generally.

Here are a couple of Matt Risinger videos detailing a mini split set-up that’s fairly typical for a Passive House or a Pretty Good House (GBA article on the 2.0 version).

Once we were on our own, in addition to going with a Zehnder ERV and a Mitsubishi ductless mini split air-source heat pump system, we also pursued the possibility of using a Sanden heat pump water heater.

After seeing it used on a Hammer and Hand project, we thought it was a really interesting piece of cutting edge technology:

Unfortunately, after getting a quote from Greg of Sutor Heating and Cooling, and a poor response from Sanden regarding questions we had about the system (they were unresponsive to emails), we decided to stick with our Zehnder, the Mitsubishi heat pump, and then go with a Rheem heat pump water heater (going with the Rheem saved us just over $6,000 in initial cost). Hopefully, as it becomes more popular in the US, the Sanden can come down significantly in price, or maybe less expensive copycat products will someday show up on the market.

Greg was initially willing to work with us, even though we were technically out of his service area, when the Sanden was involved, but once it was only a ductless mini split he suggested we find a Mitsubishi Diamond installer closer to us, which we understood. He was nothing but professional, taking the time to answer any number of technical questions and offering what proved to be sage advice regarding various details for our system.

In fact, taking Greg’s advice, we contacted a Diamond installer close to us, but unfortunately the first installer we contacted disappeared when we were trying to get him to communicate with our electrician on installation details (an infuriating and painfully common experience when trying to build a new house — especially one with unconventional Passive House details).

Finding our Installer

At this point, we were lucky to find Mike from Compass Heating and Air. He came out to the job site and we walked through the details together. He proved to be knowledgeable, helpful, detail-oriented, and extremely professional. Installing our Mitsubishi ductless mini split system with Mike proved to be one of the easiest portions of our build. We never felt like we had to look over his shoulder, making sure he got details right, or that we had to constantly confirm that he did what he said he was going to do — in fact, it was the opposite: ‘Mike’s on site, so that’s one less thing I have to worry about’.

Compass truck on site
Mike and his crew at the job site to install our Mitsubishi ductless mini split system for heating and air conditioning.

Mike also confirmed what Greg and Isaac also pointed out: comfort issues may develop if we tried to get by with just one distribution head on the main floor.

In fact, looking back through old emails, Greg was nice enough to walk me through some of the options employed by those trying to get by with a single head for an entire floor (sometimes even two floors), including leaving bedroom doors open throughout the day (ideally, even at night), and even the use of Tjernlund room-to-room ventilators.

Again, to his credit, Greg tried to stress how important it was that homeowners have realistic expectations regarding the overall effectiveness of these techniques and options.

He also was at pains to make clear how the work of any competent HVAC installer can be easily undermined by a structure that underperforms. In other words, they can design an appropriately sized HVAC system for a Passive House, but if shortcuts occur during the build and the final blower door number comes in higher than expected, or the budget for insulation gets cut, reducing R-values in the structure, then the system they designed has little chance of working as intended. Based on what he wrote, I’m guessing he has dealt with exactly this outcome in the real world — not fun for him, or the homeowners to be sure.

Consequently, by the time Mike from Compass Heating and Air got involved, we had pretty much already settled on using multiple heads. Although it was nice to hear the same consistent message from Greg, Isaac, and Mike in this regard.

In the end, we decided to delete the head in the basement, instead going with three separate heads on the main floor — the largest in the kitchen/family room, and then the other two would go in our bedrooms.

Here are the specs for our system:

Hyper-Heat Compressor (30,000 Btu)

MSZ-FH15NA  (kitchen/family room)

MSZ-FH06NA  (master bedroom)

MSZ-FH06NA  (2nd BR)

head in mbr w: section of drywall
Master bedroom Mitsubishi head and Zehnder supply, both covered to protect against construction debris.

Having the Zehnder supply diffusers on the same wall and near the head of the Mitsubishi has been working well for us. As far as we can tell, there are no discernible issues with this arrangement. By way of comparison, the Mitsubishi head and Zehnder supply diffuser are on separate walls in my daughter’s bedroom — in effect, they’re pushing air towards the center of the room from walls that are perpendicular to one another — but we can’t tell any difference in terms of performance, either when heating or cooling.

mbr and family rm erv:heads construction
Facing camera: Family room Zehnder supply diffuser with Mitsubishi head. To the left, and facing MBR: Zehnder supply and lines for MBR Mitsubishi head.

Mike was also really good about communicating the system’s requirements to our electrician and our plumber. It was nice to watch all of them walk through the details together, thereby ensuring there were no problems once it came time to start up the individual heads.

condensate and refrigerant
Components for setting up a ductless mini split: refrigerant lines, electric supply, and a drain for condensate.

Living with a Ductless Mini Split

Having lived with the HVAC system, both the heat pump and ERV, for about a year now, our only real complaint is summer humidity, which I discussed in a previous post here: HVAC (1 of 2): Zehnder ERV

This summer we’re going to try using a dedicated, whole-house dehumidifier, which we think should resolve the issue.

Otherwise, our system has been trouble-free.

In winter, the heads do make some noise, tending to ‘crack’ or ‘pop’, especially when first turning on, or when they come out of defrost mode. Although I’ve read complaints about this online, it’s never really bothered us. I remember how loud our conventional gas-fired furnace was in our last house, especially when it first turned on, so I think it’s important to remember the level of certain sounds in their appropriate context.

Also, this ‘crack’ or ‘pop’ sound is, I suspect, louder than it otherwise would be say in a conventionally built home, since Passive Houses are known to be significantly quieter because of all the air sealing and, in particular, all of the insulation surrounding the structure.

There’s also a noticeable humming sound when the compressor is going through a defrost cycle (especially noticeable at night when the house is otherwise quiet). The heads also temporarily send out cooler air during this defrost cycle, but the cycle is short enough that it hasn’t posed any real comfort issue for us.

heat pump being installed on pad
Setting up the compressor outside.

Regarding interior noise generally, the same holds true even for our refrigerator in the kitchen. We virtually never noticed the fridge in our last house when it was cycling, but in our Passive House it’s arguably the loudest, most consistent noise in the house, especially at night, or if quietly sitting and reading. Again, it took some getting used to, but not really that big of a deal.

In other words, having blocked out, or at least muffled, most of the noise from outdoors (due to extensive air sealing and extensive insulation), any noise indoors becomes much more noticeable and pronounced. The Rockwool we installed between bedrooms-bathrooms, and the kitchen-utility room for sound attenuation definitely helps in this regard (more on this in a later post).

ext line set fully sealed
Line set for the heat pump system exiting the structure after being air sealed.

Just how quiet is a Passive House? Well, one example would be the train tracks that are just a couple of blocks away: When the windows are closed the noise from a passing train is mostly cancelled out — as opposed to when the windows are open, and the train, in contrast, sounds like it’s thundering through our next door neighbor’s yard.

pvc tied down w: duct seal
Interior view of the line set exiting the house.

As far as extreme cold outdoor temperatures are concerned, the system experienced a real test with our recent Polar Vortex weather. Mike was nice enough to check in with us the day before it started just to remind me that the system could shut down if temperatures fell below -18° F, which is what our local weather forecast was predicting.

In fact, this proved entirely accurate. As temperatures eventually fell to -24° F overnight, the system was, in fact, off for a few hours (the Mitsubishi shuts off to protect itself).

With the Zehnder ERV already set to LOW, and using just a couple of small space heaters (one in each bedroom — roughly equivalent to running 2 hair dryers simultaneously), it was easy to get the interior temperatures back up to 68-70° F in less than an hour (from a measured low of 61° F when we first woke up), at which point we turned off the space heaters.

And it was just under 2 hours before the temperatures rose enough outdoors for the heat pump to turn back on. On the second day, the system again turned off, but the interruption was even shorter this time, so we didn’t even bother to turn on the space heaters.

On both days the sun was shining, which definitely helped as light poured in through our south-facing windows, mainly in the kitchen and family room. Even with no additional heat, either from the heat pump or the two small space heaters, the kitchen remained a comfortable 70° F throughout that first day, regardless of the temperature outside.

In the summer, when we have the AC running, we just set the desired temperature on the remotes and largely forget about the system. The three heads together, even in each individual space, have no problem keeping the house and individual rooms cool enough. In this case, it no doubt helps that we have a substantial overhang on the southern portion of our roof, mostly denying the sun an entry point into the home during the hottest days of the year (and the Suntuitive glass on our west-facing windows takes care of afternoon summer sun).

conduit for heat pump thru zip
Conduit for the heat pump exiting the house and air sealed with Roflex/Tescon Vana tape and gasket.

You can see more detailed info regarding air sealing penetrations through the Zip sheathing here: WRB: Zip Sheathing

refrigerant condensate next to beam
Clean, neat lines for the heat pump.

Single or Multiple Heads?

As far as using a single head to try and heat and cool the entire first floor, in our case about 1500 sq. ft., I can only say that I’m glad we chose to use multiple heads. This really hit home as I was completing interior finishes. For instance, there were times when only the head in the family room/kitchen area was running. When you walked into the bedrooms you could definitely feel the temperature difference since those heads had been turned off (roughly a 5-10° difference). As Greg, Isaac, and Mike — to their credit — were all quick to point out, for some homeowners this temperature swing would be acceptable, even something that could be calmly ignored, while for other homeowners it might well be a heartbreaking and deeply frustrating realization.

Depending on how sensitive someone is to these temperature differences, it could  prove a devastating disappointment if the homeowner is expecting uniform consistency throughout their home. Also, since much of the selling point of Passive House techniques is, in the end, occupant comfort, and not just reduced energy consumption, moving from a comfortable kitchen, for example, to a bedroom that some would find outright chilly, might induce some homeowners to ponder: ‘What was the point of all that air sealing and insulation if I’m still cold in the wintertime and hot in the summer?’ If they hadn’t been warned beforehand, like we were, it would be difficult to argue with their reasoning.

Obviously it’s only our opinion, but if it’s at all possible to fit it into the budget, by all means utilize more than one distribution head. Even if you yourself never feel compelled to turn on any of the other heads in a multi-zone system, a spouse, one of your kids, or a guest probably will want to have the option at some point.

cu beam w: zehnder and hp
Zehnder ComfoTubes and various lines for the heat pump as they enter the basement from the MBR and the family room.

In addition, I would also guess that when going to sell the house multiple heads would be significantly easier to sell to a potential buyer (who wouldn’t appreciate customized HVAC in specific rooms?) rather than trying to prove that a single head is sufficient for an entire home, no matter how small or well-designed. Thoughts worth considering before committing to a specific HVAC system.

north facade w: siding
Compressor with finished charred siding and decorative gravel-cobblestone border.

Also worth noting, utilizing the Q&A section of the Green Building Advisor website is an excellent resource for exploring options before committing to a final HVAC set-up. It’s an excellent way to hear from designers and builders who have experience with multiple ‘green’ projects, not to mention actual homeowners who live in high-performance homes and experience these HVAC systems in the real world, as opposed to just data points put into a proposed energy model (incorrect inputs, along with actual occupant behavior are just two ways a potential system could end up being profoundly inappropriate).

This kind of feedback — before construction begins — is undeniably priceless. In fact, I regret not asking more questions on GBA as they came up during the design and construction phases of our build since it is such a valuable resource of useful information.

compressor in snow
View of the same area after our recent Polar Vortex (snowfall, then below-zero temps).

The one real risk we took with our HVAC set-up was foregoing any direct conditioning in the basement, either heat or AC. In the summer, no matter how high the temperatures outdoors, the basement stays within 5 degrees of the upstairs temperatures and humidity, so no comfort issues in this regard have presented themselves. In the winter, however, the temperature remains in the 59-61° range, with almost identical humidity readings as the main floor.

ice under unit
Some ice build-up, but almost all of it on the concrete pad below, not on the compressor itself.

Most of the time this isn’t a problem for us, since we’re either working out (the slight chill gets you moving and keeps you moving), or else we’re doing arts and crafts projects, or reading on a couch under a blanket. The only time the chill gets annoying is when sitting at the computer for an extended period of time, so we may try using a plug-in space heater in the office next winter (although the challenge will be to find one that’s reasonably energy-efficient while also remaining effective).

little ice build-up
Close-up, showing very little ice present on the compressor itself.

Mitsubishi Wall-mounted Heads: Beauty or Beast

I’ve read that some interior designers, and even some homeowners, have expressed aesthetic concerns about the distribution heads. If you go on design-oriented websites like Houzz you can come across some really strong negative opinions on the topic.

family rm:kitchen hp head and zehnder

For us, they’ve never been a problem. Much like the Suntuitive glass on our west-facing windows, or even a dark or bright color on an interior accent wall, after a few days, like anything else, you just get used to it. I never found them to be ugly in the first place though.

MBR w: hp head and zehnder

I also grew up with hydronic metal baseboards for heat, while in apartments and our first home we had the typical floor supply and wall return grilles for a gas furnace — point being, the details of any HVAC system are never completely absent from any living space. There’s always something that shows up visually and, typically, that needs to be cleaned at some point.

In addition, the Zehnder ERV and the Mitsubishi heat pumps meant we didn’t have to utilize any framed soffits or duct chases (at least in the case of our specific floor plan) in order to hide bulky runs of traditional metal ductwork, typical in most homes when using a normal furnace. Unless designed with great care, these tend to be obtrusive, taking up premium ceiling, wall, or floor space. And if randomly placed simply for the convenience of the HVAC contractor, they can be downright ugly.

In other words, it doesn’t really matter if you’re building conventionally or if you’re building a Passive House, all the details of an HVAC system — whether it’s individual components, or even how these components will be placed inside a structure — should be carefully thought through (again, ideally before construction begins) to address any performance or aesthetic concerns.

Controlling and Adjusting the System

As far as the remote controls for the individual heads, we haven’t had any issues.

heat pump remote closed

For the most part, we set them to either heat or AC (roughly 70° and 75° respectively), and then forget about them.

heat pump remote open

To the extent I’ve looked through the manual, these seem straightforward, but again we haven’t really needed to do much in this regard. And when the weather is pleasant outdoors, we take every opportunity to turn off the system completely and then open windows.

Mike also explained the system could be combined with a Kumo cloud set-up, but we’ve been happy with just the hand-held remotes so far.

Routine Maintenance

And much like with the Zehnder ERV, I try to check the filters for the individual heads at least once a month (more like once a week when I was still doing interior finishes). Just as it takes much longer for the Zehnder filters to get dirty now that construction is over, the same has proven true for the blue filters in the Mitsubishi heads. It seems like about once a month is sufficient to keep up with the dust in the house.

Overall, we’ve been very happy with our HVAC set-up, including the Zehnder ERV and our Mitsubishi ductless mini split. As long as the units don’t have any durability issues, we should be happy with these systems for many years to come.

HVAC Part 1: Zehnder ERV

6

DIY Installation

Building with Passive House principles in mind, we knew that, in addition to maintaining a tight building envelope, and incorporating substantial amounts of insulation around the structure, we also needed to install continuous mechanical ventilation in order to have adequate levels of fresh air, not to mention the ability to expel stale air.

We also needed our system, either an HRV or an ERV, to be highly efficient, meaning it could hold onto some of the heat in the conditioned air even as it introduced fresh and, oftentimes, cold air by means of heat exchange as the two streams of air (fresh and stale) passed by one another inside the main unit (without actually mixing together).

After researching the many options, we ended up going with Zehnder’s ERV, in our case, the ComfoAir 350 (the various Zehnder units are based on overall cfm demand of the structure).

We only considered two other brands for our mechanical ventilation (HRV vs. ERV):

UltimateAire

and

Renewaire

In all the research I did prior to construction, these three brands showed up the most in the projects I read about.

Here’s a good debate on the Green Building Advisor website discussing brand options: ERV Choices

Another interesting option would be the CERV system. Because they’re a smaller, newer company, we didn’t feel comfortable pursuing it, but it does look like a viable option worth considering if building a Passive House or Pretty Good House.

I was also familiar with Panasonic units, but I had always read that they weren’t efficient enough in terms of the heat exchange function (or heat recovery) to seriously consider using it in a Passive House or a Pretty Good House in a predominantly cold climate region like ours, here in the Chicago area.

Our Zehnder ComfoAir 350 is said to be 84% efficient in terms of heat recovery (the same principle applies in summer, only working in reverse, when you’re trying to hold onto cooled, conditioned air). Based on what I read during the design phase, the consensus seemed to be that, although more expensive, the Zehnder has a strong track record of performance and durability.

The Zehnder also came with its own ductwork, which we knew would simplify installation, allowing us to do it ourselves, rather than hire someone else to come in and run more conventional ductwork through the house (conventional ductwork would’ve taken up a lot more space as well). Even though the unit itself was more expensive, we thought we could offset some of the total cost for a ventilation system by installing the Zehnder ourselves, thereby saving some money on labor costs.

As far as the ERV/HRV debate for Northern US states, we decided to opt for the ERV because it was supposed to help us hold onto some humidity in winter months, especially important when most structures in the Chicago area are exceedingly dry for most of the winter (and our winters are long). Although I read repeatedly during the design stage that ERV’s can also help control summer outdoor humidity entering the house, this has not been our experience at all. In fact, the ERV seems pretty useless in this regard (more on this below).

The system quote we received was easy to understand, and Zehnder was nice enough to essentially design the system, both in terms of layout (i.e., where we should put all the supply and exhaust points), along with the quantity, or cfm’s, of air for each point. In the end, after commissioning the unit, the system should be balanced, meaning the unit should be bringing in as much fresh outdoor air as it is expelling stale indoor air.

As far as Zehnder units being DIY friendly in terms of installation, in our opinion, this is highly debatable since the installation manual is far from comprehensive. Our installation manual ended at physically installing the main unit on the wall. Not very helpful.

Without a detailed installation manual showing step-by-step how all the individual pieces fit together, you end up with a pile of what initially seems like random parts.

zehnder pile of parts
Everything we need to install our Zehnder ERV. Most of the smaller components are still in the many cardboard boxes off to the right.

This was incredibly frustrating, especially since Zehnder units are purchased at a premium when compared to other competitive brands, and with the expectation of durability and design precision. It never occurred to me to ask before purchasing the unit for an installation manual, since it seemed a fair assumption that no one would sell a premium product without detailed instructions on how to put it together.

We were only able to proceed because of numerous online videos, googling Zehnder unit photos, and by staring at and experimenting with the various parts to try and figure out how it all was supposed to come together. It was an unnecessary and torturous puzzle that shouldn’t have needed solving, and it wasted hours of my life that I’ll never get back. If you do an internet search and type in: “google review Zehnder America” the experience Sean Hoppes had with his installation wasn’t all that different from ours.

Looking on the current Zehnder website (February, 2019), I can’t find a more detailed set of instructions, either written or in a video format, which is disappointing. This seems like a pretty glaring oversight on Zehnder’s part, and one that should be remedied immediately.

Having lived with the unit for almost a year now, overall we’re happy with its performance, and we feel like we could install one fairly easily now that we’ve gone through the entire process, so it’s a shame we can’t say only nice things about the product simply because the installation manual was so limited or, more to the point, non-existent.

With each video and each photo, it was possible to glean one more crucial nugget of information, which took hours, whereas a detailed written manual or a step-by-step video would’ve made the process straightforward, and by comparison, frustration-free.

The videos below were especially helpful, but, nevertheless, they still leave out quite a bit of pertinent information necessary for any first-time installer (especially regarding all the parts that need to be installed on top of the main unit):

Unless there are no DIYers in Europe installing these units, and this is the expectation Zehnder has for its units both for overseas and here in the US, not having a comprehensive installation manual makes no sense. I’m not sure how even a licensed and competent HVAC installer would fare much better without direct experience installing the units. My guess is they would be searching online for missing info much like we did.

Once we got the main unit installed on the wall, and we figured out how all the parts fit together on top of the unit, by the time we got to installing the small, white 3″ ComfoTubes and the large, gray ComfoPipe, the process became much easier.

main unit attached to basement wall
Mounting the main unit to the basement foundation wall with Tapcon concrete screws.

In regards to the gray ComfoPipe for the main fresh air supply and the main exhaust, both of which pass through the wall assembly, we found it more effective to put individual sections together on the floor, and, once fully connected, we marked the points at which the pipes met with a permanent marker.

marking comfopipe w: sharpie
Marking sections of connected ComfoPipe with a Sharpie while they’re on the floor ensures a tight fit once a connection has been made off the floor.

If you try to piece the tubes together one piece at a time in mid-air it’s much harder to gauge when the pieces are actually tightly put together. With each connection point of pipe clearly marked with a Sharpie, it gives you an obvious goal to shoot for once you have the pipe almost in its final position. More to the point, it’s obvious when sections of pipe get out of alignment, or the connection isn’t nearly tight enough — it’s much more difficult to accurately gauge if only going by “feel” once the sections of ComfoPipe are off the floor.

drilling hole for Zehnder exhaust
Making initial cut in the Zip sheathing.

Using a piece of ComfoPipe, we outlined on the interior side of our Zip sheathing exactly where we wanted the pipe to end up (trying to get as close to center as possible — makes air sealing around any penetration much easier). After a hole was cut with a 3″ hole saw, we cut out the rest of the hole using a jigsaw.

hole in Zip for heat pump pvc
Hole cut and ready for the ComfoPipe.
hole set-up for comfopipe
Hole made in our Zip sheathing, ready for the ComfoPipe from outside to make a connection with the section inside.
ext - comfo pipe going thru zip into basement
Ready to push the ComfoPipe into the house from outside to make the connection inside.
Zehnder chipmunk's back
Chipmunks are back.

Once we started using the Sharpie, it was relatively easy to get all the ComfoPipe installed and air sealed around the Zip sheathing.

comfo pipe thru zip
Making the connection between inside and outside.
setting up comfo pipe
Adding a Roflex gasket to make air sealing much easier.
comfo pipe sealed int.
ComfoPipe air sealed on the interior side with Roflex gasket and Tescon Vana.
close up comfopipe sealed
Close-up of the ComfoPipe air sealed at the Zip sheathing.
installing comfo pipe next to main unit
Finishing up the last sections of ComfoPipe as they leave the main unit.

Following the directions, we kept the ComfoPipe exit points for supply and exhaust more than 10′ apart outside, where they enter and exit the structure, in order to avoid any possibility of the two air streams mixing, which would undermine the effectiveness of the system.

comfopipe ext sealed and covered
Repeating the same air sealing process on the exterior for the ComfoPipe, adding black garbage bags over the opening with rubber bands to keep out dust, dirt, birds, and any critters that might otherwise try to enter the structure during construction.

On the outside, we made sure to extend the ComfoPipe out farther than we needed, giving us some leeway once insulation and siding were installed over the Zip sheathing. This allowed us to cut the ComfoPipe back to the proper depth before installing the permanent covers supplied by Zehnder.

comfo pipe ext close up sealed
Close-up of ComfoPipe as it exits the structure (before insulation, furring strips, siding, and its final cover).

As far as the white tubing is concerned, we really enjoyed how easy it was to put the 3″ ComfoTubes together.

During the design phase, and even after we brought the Zehnder unit to the job site, we always intended to place the diffusers for supply and exhaust points on ceilings. But after really looking at all the cuts in our ceiling service chase that would be required to make this happen, we decided to opt for placing all of them on walls instead.

It proved to be one of the better decisions we made during construction. Not only did we avoid having to make many cuts in our ceiling structure, which would’ve meant a struggle to appropriately map them out around conduit, ceiling lights, and plumbing vents, it had the added benefit of making it much easier to do ongoing maintenance at the diffusers, mainly checking on and cleaning filters, once we moved in.

cone diffuser filter
Cone shaped filter for exhaust diffusers (bathrooms, kitchen, laundry room, and basement in our case).

In fact, during commissioning, our Zehnder rep told me they have issues with homeowners not keeping their exhaust diffuser filters properly cleaned, effectively undermining the efficiency and overall performance of the units. This is understandable if the diffusers are on ceilings, whether at 8′ or 9′. It would be easy to forget about them, or even if you did remember, one can understand the reluctance to drag out a 6′ step ladder every time they needed to be cleaned. We were also told that placement of the diffusers is extremely flexible — almost anywhere can work (check with Zehnder directly just to make sure your proposed placement will work).

inside diffuser filter
Diffuser filter in bathroom after about a month. Once all the construction dust settled down from completing interior finishes, these filters don’t get dirty nearly as quickly as they once did — in other words, this isn’t bad at all.

By keeping them around 7′ off the finished floor, it’s easy for me to check and clean the exhaust diffuser filters on a regular basis (1-2) times a month. I always have 2 sets of filters, so it’s easy to remove the dirty ones, put in clean ones, and then rinse and dry out the dirty ones.

Once we decided to go through walls (both 2×6 and 2×4 framed walls), it was just a matter of deciding where in each wall we wanted the diffusers to be placed, and then cutting the corresponding hole through the wall’s bottom plate and the subfloor — being careful to check, and re-check, in the basement for any floor joists, plumbing, or electric conduit that might be in the way.

For bathrooms we placed the diffusers between showers and toilets, slightly cheating towards the showers to ensure maximum moisture removal.

changa drilling for tubes
Apparently cutting the holes through the floor looked like fun since my wife was happy to take over this chore for me. The DeWalt we were using worked great until it crapped out on us a couple of holes short of finishing. We definitely noticed a difference going back to a normal drill and hole saw set-up.

At the unit itself, Zehnder supplied us with blue (fresh air) and red (stale air) tags, to mark each ComfoTube as it leaves or returns to the main unit. This should make any potential maintenance or repair issues in the future easier to resolve, as well as helping to avoid confusion as you set in place each pipe at a diffuser.

first few return tubes are in
Attaching the white ComfoTubes to the main unit, carefully labeling each pipe for future reference.
main unit w: exhaust tubing installed
ComfoTubes being installed at the main unit.
top of silencers #2
Close-up of the top of the main unit, as ComfoTubes are being installed.
Sydney helping us
Sydney, one of our former Excel students, was nice enough to stop by and help us pull the ComfoTubes from the basement up to the first floor.
OB helping us pull and set-up the tubes
OB was also nice enough to come back to help us push and pull the ComfoTubes into place for the diffusers.
spaghetti
Pulling more tubing than we need up to the first floor. Later it’s cut back to properly fit to the various diffuser boxes.
setting up a port
Putting together a diffuser box.

Since we’re leaving the basement ceiling unfinished, it’s an ideal place to see how all the components come together: ComfoTubes meet at the diffuser box, along with the final cover for the diffuser, in this case for supply air. As you can see in the photo, there’s plenty of room in the metal tube of the diffuser box for deciding exactly where to cut it off in order to establish the finished height for the diffuser cover. In the basement we left them at their full height since there didn’t seem to be much incentive to cut them back.

basement supply diffuser
Basement diffuser box with attached ComfoTubes and final diffuser head (supply in this case).
laundry rm zehnder
Exhaust point in utility room with only one ComfoTube.

All of the diffuser boxes required at least 2 ComfoTubes, except for the laundry/utility room, which only required one. Using one of the supplied black plastic caps made it easy to block off one of the outlets in the diffuser box. These black caps are also handy when pulling the ComfoTubes around into position since they help to keep out any construction debris.

laundry rm exhaust
One outlet in the diffuser box is blocked off for the laundry room since we only required 12cfm for this area (12cfm per opening/ComfoTube).

Our kitchen required the most cfm’s, at 36, so it required a special diffuser box and 3 ComfoTubes.

kitchen octopus
3-hole diffuser box (36 cfm) for kitchen exhaust.

Again, since we didn’t place it in the ceiling, we put it across the kitchen, basically on a diagonal from the stove. So far we haven’t had any issues with cooking grease or odors, and our range hood (recirculating) seems to be doing its job just as well.

sunlight coming down comfo tubes
Sunlight coming down the ComfoTubes into the basement from the main floor.

Using scrap lumber, we were able to give each diffuser its proper stability in the wall cavities. Although the mounting hardware for each diffuser box seems rather fragile, we managed to avoid any issues.

Applying a bit of hand soap around each opening in a diffuser box made getting a solid fit between the ComfoTube, the black O-ring, and the diffuser box fairly straightforward.

connecting tube in kitchen
Attaching ComfoTubes with black O-rings and sliding clips on the diffuser box.
tubes for octopus in kitchen
ComfoTubes for kitchen exhaust going through the subflooring and into the basement.
black 0 ring
Putting the black O-ring on the ComfoTube.

It was also fairly easy to get each ComfoTube exactly where we wanted it. Since they’re so small (at least compared to traditional sheet metal ductwork), the tubes are easy to manipulate and move around, whether over a basement beam, around plumbing, electric, or any other structural component that’s not easily relocated. As long as you don’t need to make a short 90° turn, the tubes are easy to work with, so I imagine they would be ideal for renovation work in older homes.

long shot before tightening comfo tubes
It was fairly easy to put the ComfoTubes exactly where we needed them to go.

With most of the ComfoTubes in place, we just needed to add a couple of walls in the basement before finishing up the last few ComfoTubes.

raising basement wall w: Jesus and Eduardo
Jesus and Eduardo were nice enough to come back to help me put up a couple of basement walls.

Once all the ComfoTubes were installed at all the diffusers and at the main unit in the basement, we were able to pull all the lines tighter for a less messy final installation.

spaghetti comfotubes
Before pulling the tubing tight.

Using 2×4’s, we created a little window for the ComfoTubes to pass through under the floor joists. This structure helped to get the ComfoTubes moving away from the main unit in an orderly way that made it much easier to organize all the tubing once it was all installed:

zehnder installed w: tubes
All the ComfoTubes pulled tight, up by the floor joists, kept in place with some plumbing hangers.

Using plumbing hangers also kept the ComfoTubes under control and organized.

hanger straps for comfo tubes
Straps used to corral the sometimes unwieldy ComfoTubes, which can resemble spaghetti if left unorganized. They also worked well at stabilizing the gray ComfoPipe.

The commissioning of the unit, after drywall was complete, was fairly easy and straightforward, apart from a couple of wiring and electrical issues that had to be dealt with by phone with a Zehnder rep beforehand. And ordering filters from the Zehnder website has also been a straightforward and painless process so far (they’re not cheap, but they do seem to be highly effective).

The only issue we’ve really noticed with the unit is during summer when outdoor humidity levels are high. Since the ERV is constantly running, there’s no way to avoid bringing in some humid air in the summer.

And, unfortunately, it’s enough so that our Mitsubishi heat pump set-up (a future Part 2 of 2 for HVAC details) can’t properly get rid of the excess humidity either, even as it keeps the interior more than adequately cooled. We tried setting the heads to dehumidify, but they just dropped the temperature (almost to 60° F) without budging the humidity in the house very much — the rooms were freezing and clammy. As noted earlier, an ERV just can’t handle elevated levels of humidity in the summer on its own.

By having meters in various areas of the house it’s easy to see when humidity levels become a problem (we’ve been happy with our AcuRite gauges). Last summer our solution was to buy a couple of small dehumidifies, one for the first floor and one for the basement. They worked, but they also ate up a lot of energy. Setting the Zehnder fan speed to LOW seemed to help somewhat, but not enough to avoid using the dehumidifiers. This summer we’re going to try a stand-alone Ultra-Aire whole-house dehumidifier, which should use less electricity, and it should perform at least as well, if not better, at removing excess humidity.

Having read that anything above 60% indoor humidity can be problematic, especially in tighter, high-performance homes, it was disheartening to see the numbers move towards 70% in early summer. This is what prompted the purchase of the dehumidifiers.

From everything I had read during the design phase regarding Passive House, I knew indoor humidity in the summer could be a slight issue, but having experienced it firsthand, it now seems obvious that incorporating a dedicated dehumidifier in any structure that will see elevated levels of summer humidity, even if it’s only expected to last for just a few weeks, is simply a necessity. Based on what I’ve read recently, it sounds like Passive House designers, who were already doing this for Southern US states, are moving towards doing it in states much farther north. Presumably this would also hold true for anyone designing a Pretty Good House as well.

Granted, 60-70% indoor humidity (or even higher) for a couple of weeks probably won’t ruin any structure, but for us, at least, keeping it in the 50-60% range during the hottest days of summer not only gives us some added peace of mind, regardless of the hit we’ll take in terms of overall energy use, but it’s also an issue of comfort (I grew up in a house without air conditioning and still have vivid memories —all of them bad — of enduring hot and humid summer days and, even worse, long summer nights).

Much like the initial complaints of overheating, due to excessive or improper placement of glazing, especially on southern facades, this issue with excessive humidity seems to be part of the evolution in understanding how Passive Houses, or high-performance homes generally, actually work in real-world conditions. Although the concept has been around since the 1990’s, anyone building to or even just towards the Passive House standard should know they are guinea pigs to some extent, no matter how well established the idea may be in building science terms.

In the winter, we’ve had no issues. When temperatures fall below 20° F, we set the Zehnder to LOW, in the hopes that it will reduce demand on the heat pumps slightly, and it seems to hold onto humidity somewhat when the cold air being introduced would otherwise be excessively dry. Indoor humidity levels have been pretty consistent: above freezing they typically stay around 40%, and when temperatures plummet towards zero or below they’ve still stayed in the 30-35% range. We’ve rarely seen indoor humidity drop below 30%, even on the coldest days, which definitely makes a difference on overall comfort levels. I’ve also noticed that wood flooring and wood trim doesn’t shrink nearly as much as it did in our last, conventionally built home.

Also, even when we experienced record low temperatures last month (January, 2019), hitting -24° F without windchill, the Zehnder kept on running without any issues. As far as we know, it never shut off to try and protect itself from the cold (our mini-split system did, but more on that later). The product literature is somewhat vague, only noting that low temperatures could cause a unit to shut off, but it’s unclear at exactly what temperatures or what combination of other environmental conditions might cause this to happen.

Most people either tape or use sealant on the gray ComfoPipe seams to block air leakage. During our blower door test no air leakage showed up, even with a smoke pen test. Nevertheless, during our recent cold snap some frost was evident on the ComfoPipe seams, so I’ll eventually caulk these seams with Pro Clima’s HF Sealant, since there must be some air leakage, be it ever so minor.

In terms of the boost function, when turned on it pulls from all the exhaust diffusers, not just a particular bathroom or the kitchen. Again, for the kitchen, even if we’ve been roasting garlic or cooking something else that’s equally pungent, by the next morning any cooking smell is usually completely gone. There’s never been any lingering smells emanating from the kitchen.

For the kitchen, when you want to utilize the boost function you just set the ComfoSense wall unit to HIGH (the Zehnder equivalent to a standard wall thermostat). Unlike the bathroom boost switches, which run on a timer (set at the main unit in the basement), when you’re done cooking you have to remember to go back and lower the fan speed, otherwise it just stays on HIGH.

The ComfoSense unit also can display error functions or tell you when filters at the unit need to be cleaned. It also has an AWAY function, meaning you can have minimal fan speed to exchange air while you’re on vacation instead of just unplugging the unit altogether.

boost rocker switch
Boost rocker switch in the bathroom.

The boost switch in a bathroom is set to run for 30 minutes on the highest fan speed. So far, this seems to be plenty of time for it to work properly. Unlike a normal bath fan, which tends to be quite loud, even when the Zehnder is in boost mode it’s still incredibly quiet, so guests need to know they only need to press the switch once — it is indeed working.

For the bathrooms, the boost function has been working really well at removing moisture after showers. Nevertheless, in the winter, when temperatures are below 20° F and we decline to use the boost function after showers (again, hoping to hold onto some of the added humidity), the bathroom humidity levels still quickly drop from the 60’s and 70’s back to the mid-30’s in less than an hour (and this is even when the Zehnder fan speed is set to LOW).

We’ve also been happy with the diffusers, in terms of installing/removing them when necessary, but also in terms of their overall look. Whether on more neutral colored walls, or something bolder, they just look nice in our opinion.

supply diffuser
Zehnder supply diffuser on a neutral background on the wall.

They’re subtle enough to blend in to the background, but attractive enough so when they are noticed they don’t stand out in a negative way.

Zehnder exhaust diffuser
Utility room with a Zehnder exhaust diffuser on a neutral background — around the corner from the clothes dryer.
diffuser w: bold colors in bg
Zehnder supply diffuser on a much bolder background.

As far as changing filters at the unit, or even cleaning the core itself, so far it’s been a trouble-free experience.

Here’s a photo of a supply-side filter after one month of exposure in winter:

zehnder supply filter
A Zehnder supply-side filter (MERV 13) after 1 month in winter.

During the summer, of course, they look much worse after a month with so much more “stuff” floating around (e.g. pollen, debris from landscaping, insects, etc.). Also unsurprisingly, the exhaust-side filter always takes much longer to get dirty as stale air makes its way out of the structure (it probably helps that we don’t have any cats or dogs).

And since we didn’t need the framed-out HVAC chase in the corner of our Master Bath for all the ComfoTubes that we initially planned to send up into our ceilings, we ended up using this area for some much needed niche shelving for various toiletries and even some towels.

Overall, then, we’ve been extremely happy with our Zehnder ERV unit.

Windows, Doors, and Suntuitive (Air Sealing #8)

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Window Options For a Passive House (or a Pretty Good House)

Even in 2017, when the majority of our build was completed, the number of Passive House quality window and door options was increasing. Today, in 2018, they’ve only continued to grow.

For example, here is an article from the Green Building Advisor website from June, 2018 discussing high-performance window options: What Windows Should I Buy?

In addition, 475 High Performance Building Supply is selling an Austrian high-performance window, Bewiso:

A New Jersey Passive House builder, Darren Macri, has created his own product line: Wythe Windows

And GO Logic is an importer of a German brand: Kneer Sud Fenstern und Turen

They have an old blog post on their site discussing their history with the brand: GO Logic

There are also some custom, small-scale, American-made options as well:

Hammer and Hand

HH Windows

They share similar characteristics, including insulated triple pane glass, thermally broken sashes and frames, multi-point locking systems for airtight seals against gaskets on the frames, the European-style tilt-turn function, and the seemingly ubiquitous but beautiful Roto hardware.

It’s nice to see that more options are becoming available to those looking for high-performance windows in the US — hopefully this means a long-term movement towards better overall building standards in terms of quality, durability, and performance.

And here’s a quick overview on high-performance builds and the need for quality windows and doors: Hammer and Hand

Although not everyone is entirely convinced, and there’s still debate regarding exactly what’s “necessary” in terms of performance (the exception would be building to the Passive House standard, either PHIUS or PHI, where the requirements are more black and white). There’s a lot more latitude if building a Pretty Good House, or the homeowner is only looking to meet the benchmark of Net Zero.

Suntuitive Dynamic Glass for Our West-Facing Windows

When my wife’s cousin found out we were trying to build a high-performance new home (a mix of Passive House and Pretty Good House), he suggested we incorporate his company’s self-tinting glass. Used largely in commercial applications since its introduction, the product is beginning to make inroads into the residential market as the cost comes down: Suntuitive

For anyone near the northwest suburbs of Chicago, you can see the glass in person at the Ziegler Maserati dealership in Schaumburg, Illinois: Exterior View

As the product has continued to evolve, they’ve been able to remove much of the “green” look to the glass. This is evident in the Ziegler dealership glass, but even in that application I didn’t think that it was all that prominent. The overall look of the glass was still impressive.

As to function, the Suntuitive coating between the layers of glass adjusts its level of tint based on the temperature of an inner layer. In the summer, this has obvious benefits when high temperatures combine with glaring sun to enter a structure, particularly in the east in the morning or the west in the afternoon (even to the south without some protection with overhangs). But the really nice thing about the product is that it doesn’t tint on the coldest days in winter, allowing for some solar heat gain and natural daylight exactly when you want it most on sunny, wintry days.

For energy reasons, and also personal aesthetic choices, we decided to forego any windows on the east side of our house. Instead, we just have our front door facing the street (it has a limited amount of privacy glass to let in some morning light). On the other hand, because we wanted to use a significant amount of glass on the west side, which faces our backyard, and we knew overhangs couldn’t offer much relief from the summer afternoon sun, Suntuitive was a great solution for us — especially since we wanted to avoid using blinds or curtains as much as possible.

Following Passive House principles for glazing, we wanted to optimize our views and connection to the outside through our limited and strategically placed number of windows.

Here’s a useful video showing the effects the sun can have on a structure in various seasons:

And here’s an interesting video discussing the challenges associated with managing both solar orientation and scenic views when they’re in conflict:

For our house, we only have a single window to the north (for my daughter’s bedroom), while the majority of our windows are on the south side, where we spend most of our time in the living spaces (open kitchen and family room). In effect, we’ve limited our windows in private areas of the house, mainly two bathrooms. Besides energy concerns, we didn’t think it made sense to add additional glass to our north, mainly because our neighbor’s house blocks any meaningful views while also reducing privacy.

Additionally, we have a significant overhang on the south side, which allows us to block out most of the summer sun while allowing in plenty of winter sun for passive solar heating during our coldest months, so the windows on the southern facade easily take care of most of our daylighting needs.

By utilizing the Suntuitive glass on only the west-facing windows (family room and master bedroom) it allows us to maintain our open view of the backyard while avoiding migraine-inducing summer afternoon sun.

Here are the specs for the particular glass we chose to use (they have a wide variety of options, including color variations): Vertical CrystalGray Triple Glaze Performance Sheet – Lee-Whetzel

Although we lose some potential solar heat gain through these windows in winter (compared to the glass in a typical Passive House certified window), we feel it’s more than compensated for by the blocking of hot, bright summer afternoon sun.

Here’s a company video describing the Suntuitive product in real world applications:

Unilux Windows and Doors

My wife’s cousin suggested a couple of options for the Suntuitive glass: Kolbe Windows or Unilux Windows.

We went to see the Kolbe windows in a local showroom, but they didn’t seem impressive. It also didn’t help that the salesperson was dismissive of the product, suggesting that if we were considering Kolbe we should just use Marvin instead (another brand they sold). The salesperson literally had to wander around looking for a sample unit, eventually finding one buried in a corner. We’re not even sure if what we saw represented the full breadth of the Kolbe product line.

At any rate, since Unilux was willing to work with the Suntuitive glazing, it made it easy to go with them rather than trying to convince another Passive House certified window maker that Suntuitive could be compatible with their product line.

[Note: Suntuitive is constantly adding new manufacturers willing to work with their product, so contact them directly if you have a specific brand you’d like to use on your own project.]

After deciding to go with the Unilux windows and doors, we ended up with the following specs:

[Please note: The numbers below were mostly supplied to me by my Unilux window rep. Following up with a Unilux rep on the East Cost, Scott Gibson, from Green Building Advisor, received different information. If you’re contemplating using Unilux, contact your local rep or the company directly in Germany for written confirmation regarding performance numbers — especially if you’re running data through a program like PHPP.]

Main Floor Windows (excludes west-facing windows with Suntuitive):

  • Interior wood with aluminum-clad exteriors
  • Glass: Unilux Super-Thermo 3
    • Triple pane with a reported R-ll center of glass
      • R-8 for whole window once frames are included
  • U-factor of 0.18
  • SHGC of 0.53

2-Basement Windows:

  • Isostar: interior uPVC with exterior aluminum-clad
  • The same glass as the main floor windows.

Two doors:

  • One for our front entry, and one for our kitchen. They both have the R-11 center of glass glazing, with the kitchen door having a significant amount of privacy glass (it faces south), which is really enjoyable on cold days with the sun shining.

We chose PVC for the basement windows to save some money, but also because we thought the natural wood finish on a basement window might look out of place — we’re painting the concrete foundation walls, and partially drywalling an office area, but otherwise we’re leaving the basement unfinished (it will look finished for our tastes at any rate).

The total cost for the windows and doors was just over $26,000 (including the Suntuitive for the windows facing west), with the two doors representing almost $10,000 of this total.

In regards to the Suntuitive glass, it is currently selling for roughly $31/sq. ft., depending on specific application requirements. You can contact my wife’s cousin, Dan, at his email address if you have technical questions, or if you’d like to get a quote for your own project: leed@pleotint.com

I don’t believe the Unilux windows and doors are technically certified by PHIUS or PHI, but their performance metrics are close to the necessary requirements, so we were comfortable using them, especially since we had no intention of pursuing official Passive House certification anyway.

Window Bucks

After firing our two GC’s in February, 2017, we lost a few weeks as we scrambled to cut ties with them while simultaneously lining up new subcontractors to keep the project moving forward.

Once things were back on track, I was able to begin installing the window and door bucks in preparation for the delivery of the eventual windows and doors.

Using 3/4″ CDX exterior plywood, I installed the bucks so they would extend out far enough to meet up with our eventual two layers of 2″ Rockwool Comfortboard 80 and two layers of furring strips for our ventilated rainscreen (vertical and horizontal since most of our charred cedar siding would be oriented vertically).

Here’s how a similar set-up looked on Hammer and Hand’s Madrona House project:

We decided to go with “innie” windows, so our windows would be placed near the center of our wall assembly to optimize their energy performance. Placing windows near the center of the wall assembly also creates nice shadow lines on the structure throughout the day. Overall, we just really like the way recessed windows look on a house.

Prior to construction, I created a mock wall assembly with a window buck, which proved to be good practice for building the real thing.

mock-wall-assembly-w-sealant-in-sun
Mock-up of the wall assembly put together before construction began.

Mock wall assembly after practicing with the tapes:

mock-wall-assembly-w-tapes
This mock wall assembly gave me the chance to practice applying these tapes before doing it for real on the house.

It’s also worth mentioning that it’s important with these tapes to make sure that once applied you go over them, applying pressure, to ensure the adhesive is properly activated. 475 HPBS always included at least one of their blue Pressfix tools in each box of tape that I ordered. The tool is roughly similar to a bondo spreader.

pro-clima-pressfix.jpg
Pressfix after heavy use.

We were following many of the details in Hammer and Hand’s Madrona House project:

I watched their videos dozens of times, especially this one, trying to make sure I got all of the details right. Their Best Practices Manual was also invaluable as I kept referring to it throughout the duration of the build (an incredible gift to contractors and self-builders alike who are tackling a high-performance build for the first time).

Once each buck was installed, I went around and used HF Sealant to seal all the gaps, seams, and screw holes in the window and door bucks.

BR #2 window buck with HF sealant
First window buck installed.

Here’s a close-up of the same window as the HF sealant is being applied:

close up of BR #2 with HF sealant
HF Sealant at the transition between the Zip sheathing and the window buck.

And here’s a different buck being sealed on the interior surfaces:

lwr rgt int wdw buck w: hf sealant
Using HF sealant to seal seams, imperfections, and screw holes in the plywood window bucks.

Another view of the buck being sealed up with the HF sealant:

int wdw buck w: hf sealant

With the bucks installed, I could then begin applying the various air sealing tapes to all the surfaces of the bucks. I decided to use the Pro Clima line of products, available from 475 HPBS, after ordering them and using them to create my mock wall assembly.

The other option would’ve been to use the Siga brand of air sealing tapes, available from Small Planet Supply, or the black Huber Zip sheathing tape.

Although clearly based on my own personal prejudice rather than scientific evidence, I was reluctant to use the Zip tape, 3M tape, or something similar, mainly because I knew the European brands have a much longer track record of success.

Yet another option would’ve been to use liquid applied membranes (e.g., Prosoco, again Zip, or others), which I’ll address later, when noting the details for sealing up my front door buck area.

Knowing that corners and other areas where elements meet up could be problematic for proper air sealing, as pointed out by Sam Hagerman in this Hammer and Hand video:

I started by addressing some of these areas first. For example, here’s the lower right of a window buck where it meets the Zip sheathing:

lowr rgt buck 1st profil at zip

By building up the corners in this way I was hoping to guarantee complete coverage against air and water infiltration at these tricky points.

lower rgt buck w: profil at zip
Same area with overlapping top layer.

Here’s the top of the buck where it meets up with the Zip sheathing:

profil on buck meeting zip
Corner where the buck meets the Zip protected again with 2 separate overlapping pieces of tape.

The Profil tape, which splits into thirds on the back, makes corners much easier to tackle.

After using the Tescon Vana in the upper inside corner of the buck, I used the Profil tape to address the upper outside corners of the bucks:

int buck w: tvana and 1st profil
Tescon Vana, then Profil for this upper outside corner.

Here’s two views of the second top piece for this area:

outside upper rgt w: profil
Putting it in place before making a small cut to fold over the outside edge.

Here’s another view of the same area, this time looking at the buck head-on:

upper rgt of wdw buck w: profil
Same area after cutting the piece and ready to fold it down into position.

By making small cuts in the Profil tape with a razor blade, corners are easy to shape to the form you need. Although making a cut while the tape is already in position is relatively easy to do, avoiding any damage to underlying layers is obviously very important. For this reason, it’s probably safer to make cuts before getting the tape into position.

For instance, an initial cut in the Profil tape:

cutting profil for corner

And then making a fold to establish the basic shape for an outside corner:

cut folded profil for outside corner

Once you initially set the tape in its position, gently remove the white backing paper, trying to avoid moving the tape too much, which would change its position or cause wrinkles.

I didn’t use the Profil tape for the two lower outside corners since these areas would eventually get throughly covered by the Extoseal Encors sill pan tape.

Once the corners were taped up, I moved on to the bottom of the buck, using the black Contega Solido Exo tape.

First piece of Contega being applied to the bottom of a buck where it meets the Zip sheathing:

contega lower lft corner

The same area once the piece of Contega is cut to allow it to partially wrap up the side of the buck:

contega under and up side
First piece of Contega being installed.

Note the white paper backing that helps to position the Contega exactly where you need it, while also reducing the chances for wrinkles to form (an area for potential air leaks).

The Contega, like the light blue Profil, comes with a 3-part split backing. Although this 3-part backing helps a lot, I still struggled at times to avoid wrinkles with the Contega. The Contega is noticeably thinner than the blue Tescon Vana, which is probably why I found the Tescon Vana much easier to use. In fact, if I had it to do over, I would just use a wider version of the Tescon Vana to replace the Contega.

The nice thing about the wider versions of the Tescon Vana is it also comes with a split back for ease of placement:

tescon vana 6 w: split backing
6″ Tescon Vana with split backing.

Once an initial piece of Tescon Vana (3″) covered the exposed front outside edge of the plywood, I applied the wider Tescon Vana (6″), before applying the Contega to the Zip – buck – bottom piece of Contega connection, effectively bringing these adjoining areas together.

starting contega up lft sde buck
Second piece of Contega going up the side of the window buck.

Getting the first third of the Contega attached to the Zip before removing the remaining 2 strips of white paper backing seemed to help get it to sit flat without too many wrinkles.

contega up lft sde of buck pulling strip
Removing the smallest of the 3 strips of white paper backing.

The Contega was then cut so that it lapped the first piece of Contega on the bottom of the window buck.

And here is the Contega as it ends up on the top of the window buck:

close up contega up over top of buck
Corners being covered multiple times: HF sealant, Profil tape, and then Contega tape.

Making progress across the top of the window buck, building up the layers in shingle fashion — first with the Tescon Vana on the exposed front edge of the plywood, then moving up with the Contega, before finishing with a final strip of Tescon Vana on the Zip sheathing:

progressing across top of buck
Moving across the top of the window buck.

Top of the window buck almost complete:

upper lft buck w: top pce of contega

Same area finished off with a strip of Tescon Vana:

head of wdw buck finished w: t vana

Here’s a side view of a completed window buck. Note the sloped top, achieved with a piece of beveled cedar siding. Hopefully water won’t make its way to this area above each window or door (it’ll have to get past 4″ of Rockwool), but the slope that’s present will hopefully encourage any water that does so to harmlessly drip off rather than hang around to cause potential damage.

prepped wdw buck w: sloped top

Once the exterior of the window bucks were complete, I went inside to cover the interior head and legs of each buck.

contega interior of buck
Contega on the top and sides of the interior of each buck.

Here’s a Siga video I only recently came across, showing another way to deal with corners:

The last area to be addressed was the window sills. For this area I used the Extoseal Encors product. It’s vapor-closed, highly pliable, but also thick to prevent any water that ends up on the sill from entering the structure.

I really enjoyed using the Extoseal Encors, although you do need to avoid thinning it out as you wrap it around outside corners.

The only time I had a problem with it was on my last window buck. Temperatures were rising and I was working in direct sunlight. It was only in the high 60’s, but that was enough to cause some bubbling in the material.

extoseal bubble in sun
Some bubbles caused by working in the sun.

In my experience, the Extoseal Encors performed at its best the colder it was outside.

window buck almost complete
After a second row of overlapping Extoseal Encors on the sill to the interior, this window buck would be complete.

Door Bucks

Once the window bucks were installed, I could move on to the two door bucks (front entry and side kitchen entry).

legs of kitch buck installed
Installing the door buck for the side, kitchen door.

Plywood portion of the door buck complete with bottom piece installed:

kitch dr buck looking down at plywood
Looking down at completed plywood door buck.

Note the small voids in the plywood pictured below. Because of gaps like these, I chose to cover the edge grain of all the plywood window and door bucks with the HF sealant before applying tapes, just to ensure no air could migrate through the layers of plywood.

lwr rgt door buck w: plywood
Outside corner of door buck.

After completing the plywood door buck, it was time to give it support from underneath. Although about 2/3 of the door would rest on the subfloor/floor joists, leaving that remaining 1/3 unsupported made me nervous.

While there’s plenty of information available regarding the use of window bucks, I found surprisingly little regarding the installation and weather-proofing of door bucks. I couldn’t find any information for this detail in my Passive House books, or any description of it online, so I consulted with a local GC to come up with a solution.

As an aside, Rick, from Cypress Builders in Palatine, Illinois, proved to be an invaluable resource for a whole host of design problems and issues during our build. After firing our two GC’s, he was kind enough to take on the role of building consultant: Every couple of weeks I would come up with a list of questions, and he would stop by the job site to run through answers and possible solutions.

To his credit, the level of detail involved in a Passive House build didn’t scare him off — it did for many of the other GC’s, carpenters, and siding companies I had out to the job site for estimates — none more blunt than one particular carpenter who could only shake his head over and over as I went through the components of our wall assembly before finally blurting out in frustration: “Why the fuck would anybody build this way”. It’s funny now, but it wasn’t at the time when I was struggling to line up subcontractors in order to try and finish the project.

Rick was incredibly generous with his time, knowledge, and experience — it’s no overstatement to say it’s doubtful we would’ve completed our build without him. His decades in the building industry allowed him to offer sage advice, and I always ended up calmer and more confident about completing the next stage of the build after each of his site visits. I would definitely recommend him to anyone in the Chicago suburbs looking to build or remodel (the mix of experience, honesty, and excellent communication skills is hard to find).

And for any other DIY self-builds, I can’t recommend strongly enough how important it is to look for a similar mentor for your own project. Even if things are going well, whether in the design stage or even the actual build, it can’t hurt to have a construction veteran stop by and try to spot problems, or potential problems. A second set of eyes, eyes that have seen decades of construction acumen along with plenty of stupidity, can only improve the quality of your own build. As invaluable as online resources like GBA, BSC, and Hammer and Hand have been to our build, none of those resources could visit our job site directly, so someone like Rick helped to complete the circle of advice and knowledge that can make the difference between a successful build and total disaster.

To try and give the door buck structural support, I first installed a layer of Rockwool against the green Zip sheathing directly underneath the door buck, attaching it initially with some construction adhesive. I was hoping this would act like the foam in an insulated header.

rockwool for under door buck
Prepping the Rockwool for the door buck.

After the Rockwool (2″ Comfortboard 80), I attached two 2×8’s with eight Headlok screws through the Zip, rim joist, and some of the floor joists as well.

We would eventually use these screws extensively to attach our first layer of furring strips through two layers of 2″ Rockwool Comfortboard 80 and our Zip sheathing (again, more on this later). I also used their 4 1/2″ screw to correct a couple of window headers that were out of square. With the spider drive, they work incredibly well.

Unfortunately, when installing the two 2×8’s I accidentally compressed the Rockwool slightly, requiring a final layer of 1/4″ plywood. Thankfully I was able to avoid compressing the Rockwool for my front door buck, so the 1/4″ plywood wasn’t necessary.

kitch buck w: 1:4 plywood
Layers of support underneath the door buck. The Rockwool is intended to act as a thermal break, much like foam in an insulated header.

Another view of the door buck with basic components installed:

kitch buck w: plywood installed
Note the visible gap between the bottom of the buck and the Rockwool on the foundation below. This gap was closed with additional pieces of Rockwool cut to fit.

Because of the Rockwool, sealing the end grain of the 2×8’s would’ve been difficult with only the tapes, so I first applied the HF Sealant to try and create a monolithic surface:

Side Door - built out w: sealant
HF Sealant covering the Rockwool and the end grain of the 2×8’s. Additional Roxul installed between the buck and the Roxul on the exterior of our foundation to close this gap.

If I had it to do over, I’d use Prosoco’s Fast Flash since, unlike the HF Sealant, it’s vapor open, so probably a better long-term solution should moisture of any kind find its way to this area. Once the HF Sealant was dry, it was straightforward to apply the Extoseal Encors.

But before applying the Extoseal Encors, I applied the tapes in the same pattern and manner as I did for all the window bucks.

I also added additional layers of Rockwool and a final layer of pink rigid foam to bring everything out to the same plane before installing the Extoseal Encors.

taping side of door buck - south side
Applying the tapes to the kitchen door buck.
lwr rigt kitch buck w: foam and extoseal
Extoseal Encors across the  bottom face of the door buck.

Also, in addition to the Extoseal Encors across the face of the pink foam, the concrete sub later applied a layer of EPDM rubber to try and prevent moisture intrusion/damage in this area.

lwr lft kitch dr buck w: first row extoseal
Second row of Extoseal Encors, wrapping down over the first.

Although the Extoseal Encors looks great when it first goes on, once temperatures rise it becomes gooey in the sun, so it was a challenge to maintain its integrity before the door went in. If I could do it over, I would hold off on installing the Extoseal Encors until the day before, or the morning of, the door’s installation.

lower lft kitch dr buck w: extoseal
From outside, looking down on the bottom left corner of the door buck: last piece of Extoseal Encors installed.

From outside, a close-up of the right outside corner of the door buck:

lower rgt kitch dr buck w: extoseal
Extoseal Encors wrapped around the outside corner of our kitchen door buck.

And a view of the completed door buck:

kitch door buck w: extoseal installed
Ready for the kitchen door.

For the front entry door buck I repeated the same assembly of components (minus the 1/4″ plywood and pink rigid foam), the only major change a switch to Prosoco’s R-Guard series of products; namely their Joint and Seam and Fast Flash, replacing the Pro Clima tapes and HF Sealant.

Before the start of construction, I intended to use the Prosoco products for all the air and water sealing details, but when it looked like construction would happen in the winter of 2016-17 I knew I had to change to tapes since most of them can be applied below 20° F (this includes the HF sealant), while the R-Guard series of products can only be applied in above-freezing temperatures (you’ll want to contact the manufacturers for exact installation directions and requirements).

Since it was August by the time I did the front door buck, I decided to try the Prosoco products just so I could compare them to the European-style tapes I had been using. I was able to find the R-Guard series of products online at World Class Supply.

frt dr buck looking down j and seam
Lower left corner of front door buck. Pink Joint and Seam on the bottom, red Fast Flash running up the leg of the door buck.

Exterior head and legs of the door buck covered in Joint and Seam and Fast Flash:

lft ext side of frt dr buck w: fast flash

Upper right corner of the front door buck after applying Joint and Seam and Fast Flash:

upper rgt frt dr buck w: fast flash

Lower left outside view of the front door buck after Rockwool, 2-2×8’s, Joint and Seam, and Fast Flash have been installed and applied:

front door lower left w: fast flash

There were a few gaps between the Rockwool and other components around the house where the Joint and Seam seemed to work surprisingly well as a sealant. Even though the Rockwool is fibrous, the Joint and Seam was still able to stick tenaciously — hopefully it continues to work in the long-term.

And here’s a couple more pics of the completed door buck, ready for the front door:

front door entry low shot of fast flash
Completed bottom section of front entry door buck.

Standing indoors, looking down at the right corner of the front entry door buck:

front door entry w: fast flash
Fast Flash around the perimeter of the front door buck.

As things turned out, this front door buck would end up exposed to construction foot traffic and the elements for about 4 months. Having a cheap, temporary front door helped to keep most of the rain out, but even so, the Fast Flash held up surprisingly well. Apart from a couple of tiny touch-ups with additional Fast Flash just prior to the front door being installed, there was little damage to the membrane.

And once the house was done, most people when entering or exiting skip the metal flashing and the door’s threshold (the area I was trying to give added support), preferring to step directly from the concrete stoop into the house and onto the tile since it feels more natural, but it’s nice to know that if these areas ever do see serious weight (e.g. moving heavy appliances or furniture) that it’s fully supported.

Just recently I had time to look through William Maclay’s book The New Net Zero, a fantastic resource I would’ve loved to have before and during our build, and I noticed in a diagram on page 343 the use of a (4″ x 4″) piece of fiberglass angle: “… fasten to rim joist to support extension of floor at door opening”.

If I could do it over, I would use the fiberglass angle instead of the two 2×8’s. Last winter we had a cold spell for about two weeks where temperatures stayed in single digits, and although I checked behind my Rockwool in the basement just below my two door openings at the rim joists for any signs of moisture issues and found nothing (luckily), the fiberglass angle seems like a much simpler solution since it’s thermally broken and much smaller than my two 2×8’s, which would’ve meant I could’ve almost completely insulated below the door bucks while also giving this area plenty of long-term structural support.

Of course, consulting a structural engineer or architect wouldn’t hurt either, just to establish exactly what’s required for tackling this area.

For anyone who’s interested, I found the following suppliers for fiberglass angle online:

Grainger
Strongwell

Air Sealing Products: Tapes or Liquid Membranes?

In regards to air sealing, I was really impressed with the Pro Clima series of tapes and their HF Sealant. I was equally impressed with the Prosoco R-Guard series of products (Joint and Seam, Fast Flash, and Air Dam).

Because I found the Prosoco series of products slightly easier to use since they’re less fussy to apply, I would choose tapes or liquid membranes based on the weather conditions of the job site: If it’s going to be too cold to use the Prosoco, then I would use the tapes (and the HF Sealant). Otherwise, I’d probably stick to the liquid membranes. I’m guessing the choice typically comes down to personal preference of the installers (apart from weather restrictions), or what the architect specifies on the drawings.

Here are some videos showing various liquid membranes in action:

And there are now other copycat products available:

And 475 HPBS and Pro Clima now offer their own version of a liquid applied membrane:

VISCONN

Completing Air and Water Sealing of the Windows and Doors (Interior)

Our Unilux sales rep was nice enough to arrange for Bob Riggs and his crew to come down from Wisconsin to install all of our windows and doors. After firing our two GC’s, we really didn’t know who to use for the install. Not many contractors in the Chicago area have experience with these type of windows and doors, so it was hardly straightforward to find someone.

We had ordered our windows in September, 2016, we had fired our GC’s in February, 2017, and we were finally able to install our windows June, 2017. It had been a long wait, so we were excited and nervous to watch them go in. Familiar with Germany’s reputation for engineering excellence, it was one of the more exciting aspects of the build.

guys putting in kitchen window
Kellum, Tony, Bob Riggs, and his son Brian placing our kitchen window frame.

Bob and his crew did a great job for us. We’re lucky and extremely thankful that they were willing to come down to help us out of a jam. And the guys they used from JPK Builders to help them with the install were also extremely professional and easy to work with (more on this below).

As far as installation details, for the most part the guys followed the steps outlined in this Hammer and Hand video, only changing the Tremco illbruck tape for Hannoband 3E tape:

I chose to go with the Hannoband 3E tape, but there are any number of options for air and water sealing around windows and doors:

Here’s a video detailing the use of the Hannoband 3E black expanding foam tape, which I purchased from Small Planet Supply:

The Hannoband tape has some nice characteristics, such as adding some R-value to the gap, it’s water and air tight, but it’s also vapor-open. It’s also easy to work with and install, it performs really well, and using it means not having to fill the gap between window and framing with canned spray foam (prone to failure according to some Passive House designers and builders). Overall, it just seems like an elegant solution for air and water sealing what can otherwise be a difficult gap to deal with.

Here’s a short video from Tremco showing how these expanding black foam tapes work:

And here’s a photo of the Hannoband 3E, dramatically showing just how much expansion it’s capable of if left unimpeded:

Hannoband 3E showing expansion
On the left, Hannoband just cut from the roll of foam tape. On the right, Hannoband after 48 hours of unimpeded expansion.

It also comes in different sizes to better match the gap that needs filling.

The photo below was taken shortly after installation, before the foam had a chance to fully expand.

upper rgt wdw fr blk foam b4 expanding
Upper right corner of a window with the Hannoband 3E tape.

Here’s a similar corner after the foam has had time to completely expand. The HF Sealant in the corner is just added insurance against air leaks.

upper left int wdw frame w: blk foam
Hannoband 3E tape fully expanded.

It was pretty impressive to see gaps like this on the day of installation:

hannoband-tape-before-full-expansion.jpg
Daylight coming in right after the installation.

Only to come back the next day to find the gap completely closed by the expanding foam tape:

lft side wdw frame gap filled w: blk foam
The gap is completely closed the next day.

I put the Hannoband on ice the morning of the installation since the cold is said to slow down the rate of expansion, giving installers plenty of time to set windows and doors.

A closer view of the Hannoband 3E tape fully expanded between the window buck on the left, and the window frame on the right:

lft side of frame close up blk foam

A closer view of the upper left corner of one of the windows after the Hannoband has had a chance to fully expand:

upper left corner of window w: Hanno tape and HF but before Profil

The tapes aren’t cheap, but I thought they were worth every penny.

For the bottom of the window, it wasn’t really clear if the Hannoband tape was appropriate for this area, so I followed Hammer and Hand’s lead, using backer rod to fill the bottom gap before applying HF Sealant (instead of Air Dam like in their video).

bottom of int wdw frame w: backer rod
Backer rod being installed into the bottom gap under the window from inside.

Lower left corner of the window after the Hannoband tape, backer rod, and HF sealant have been installed.

lower lft int wdw frame w: dab of HF
Interior lower left corner of a window after the Hannoband tape, but before the Profil tape has been applied. 

Later, for the basement windows, when I had the Prosoco R-Guard series of products on hand, I completely sealed the interior side of the two windows with the Air Dam product, which worked really well. I also used the Air Dam to seal the connection between my basement slab – rigid foam – and foundation walls. It worked really well in that application as well.

lower ft int base wdw installed
Basement window before the white Air Dam has been applied between the buck and the window frame.

Once the Hannoband tape had a chance to completely expand (roughly 48 hours), I proceeded to tape the perimeter of the windows and kitchen door, both from the interior and the exterior. This included the exterior sills (a common air sealing technique for European windows; considered a big no-no for American-style windows).

Unfortunately, when I was outside, before applying the Profil tape across the bottom of each window, I forgot to stuff in some Roxul Comfortboard 80 (as suggested in the Hammer and Hand video above). I only realized this misstep after reviewing photos for this blog post. Worried about potential negative consequences, I asked a question on the Q&A section of GBA, and I also contacted Floris at 475 HPBS. Although this roughly 1/8″ tall gap is an unnecessary thermal bridge (thanks to my mistake), it shouldn’t impact the long-term durability of the windows or the bucks.

I rented a FLIR thermal imaging camera to check this area, and to just see how the overall structure of the house has turned out in terms of air sealing and insulation (we moved in this past Spring, 2018). Unsurprisingly, the space between the window frames and the bucks/drywall is one of the weakest areas on the entire house. Fortunately, the sills don’t show up any colder than the rest of the frame (I’ll delve more into this in a later post, including some FLIR images from around the house, after detailing the installation of our exterior insulation and siding).

For the front door, we held off on installing it until later in the build in order to protect it from the construction process as much as possible.

close up lower lft wdw finished w: HF sealant
Interior view of the gap between buck and window frame taped with Pro Clima Profil tape.

Using the Profil tape for this made the process a lot easier. With its 3-part split backing, I could use the narrowest section on the window frame. It was important not to get too much tape on the frame in order to avoid interfering with final trim details (in our case, drywall returns).

On the exterior I tried using the Tescon Vana initially, thinking the gap was wide enough between frame and buck, but the Profil tape was simply much easier to use in tight spaces.

rgt side ext wdw frame finished w: tvana
Left to right: exterior gray window frame, Tescon Vana, and tape-covered window buck.

I added a little HF Sealant to all the corners just for added protection against air leaks and water intrusion.

taping ext of family rm window frame
Applying the Profil tape to an exterior frame.

From the outside in we had Profil tape, the Hannoband tape, and then another layer of Profil tape on the interior. Doing it this way involved some time and money, but I thought it was worth it to protect against air and water infiltration for the long-term. I would also only have one chance to get these details right, so some added redundancy also meant added peace of mind.

upper lft int buck corner finished w: hf sealant
Another view of a window completely taped and sealed in an upper left corner.

I also addressed the brackets on the top of the windows with a mix of HF sealant and tape after the Hannoband had fully expanded:

clip above window before Profil #2
First HF sealant applied around the bracket.
clip above window w: Profil
After the HF sealant, the Profil tape is applied.

Over-insulating High-Performance Window Frames

When the window bucks were made air and water tight, I took the advice of Hammer and Hand and over-insulated the exterior frames with rigid foam:

I wanted to use Roxul for this application, but it would’ve taken too much time to order and deliver to site (roughly 2 weeks), and the foam was frankly cheaper and readily available at Home Depot. We tried to go “foam-free” as much as possible, but this was an area where we made a compromise — insulated headers and the gap between our basement slab and foundation walls were the two other areas where rigid foam was used to any great extent.

The exterior aluminum cladding had been held back 1″ from the edge of the wood window frame, allowing me to install 1.5″ of foam between the edge of the aluminum cladding and the window buck (the 1/2″ gap around the perimeter of the window buck opening allowing for proper placement of each window).

over insulated frames
Over-insulating the window frame.

For the most part this went well, but there were some areas where the interior 1/2″ thick piece of foam did overlap the aluminum frame slightly. As Speier points out in the video, this probably short circuits the intended thermal break somewhat, but by how much I don’t really know (hopefully not entirely).

Also, even if over-insulating the window frames is executed perfectly, it still leaves the window bucks themselves as thermal bridges. I’m sure these show up in the PHPP (the Passive House Planning Package) used for energy modeling, but I’m guessing the energy penalty is slight.

Instead of using 3/4″ plywood or 2x framing lumber to create window bucks, some builders, trying to avoid this area of thermal bridging, have used Thermalbucks as an alternative, but depending on the thickness of the wall assembly there may be limits to their use.

Another view of the over-insulated frame:

lower lft wdw buck w: foam on frame

I’ll add additional photos of the windows and doors to a later blog post discussing exterior insulation, the ventilated rainscreen, flashing details, and our siding.

kitch dr from int w: sun
Kitchen door installed.

Issues Arise with our Unilux Sales Representative

The biggest disappointment regarding our new windows and doors was the behavior of our Unilux sales rep.

For instance, when Riggs and his crew were ready to set the first window in place we realized the integrated window sills were going to be way too short (the Unilux sills ship separately and need to be screwed to the front of each window unit). Our Unilux rep immediately suggested moving the windows farther out, near the outside edge of the bucks, in order to make these shorter sills work.

There are a couple of reasons why this was infuriating. First, and most importantly, it would’ve undermined the integrity of the windows since they would’ve been resting solely on the 3/4″ plywood window bucks, rather than the 2×6 framing (the units were heavy, especially our family room and master bedroom windows, which were each 9′ wide and 4′ tall). Secondly, his suggestion immediately told me he had not bothered to look at the construction drawings and Hammer and Hand videos I had emailed to him so he could order the proper sized sills and better understand the wall assembly the windows were going into. The drawings clearly note the proper placement for the windows, and I had explicitly noted this desired mid-wall position in an email.

Luckily, before I could say anything, Tony, one of the carpenters, spoke up and pointed out that the windows needed to be screwed into the 2×6 framing members. I can’t tell you how grateful I was that he had the courage to speak up (in my experience, most people wouldn’t).

The guys also pointed out that I could have custom sills made and then installed during the siding process. Not the end of the world. Sounds good.

suntuitive in crate
Suntuitive glass delivered in a crate. For our application it needed to be installed into two empty Unilux frames on site.

Later, our Unilux rep was leading Riggs and the guys through the process of installing the Suntuitive glass in the empty west-facing window frames. The guys seemed visibly nervous, and understandably so, as our Unilux rep led them through the process for the first time.

Once the Suntuitive glass was installed, the guys broke for lunch. The Unilux rep then pointed out to me when we were alone that of the 6 pieces of glass 4 of them had the Suntuitive glass logo installed upside down. He shrugged and smirked, perhaps suggesting that it was the carpenters’ fault, or that it was no big deal.

Fair enough, I guess, since it doesn’t impact performance but boy, does it look dumb.

Suntuitive upside down

Instead of taking a few extra seconds with each piece of glass to make sure that it had the proper orientation, our Unilux rep either forgot to do this, or he just didn’t care. It was hardly the carpenters’ fault since they had never installed Suntuitive glass before.

Still later in the day, when it came time to start installing handles, rather than having what I had ordered on site, our Unilux rep had a cardboard box filled with random handles of various styles: “Is this yours?” “No.” “Is this one yours?” “No.” He only had 2 of the correct handles out of 9. At the very least, this gave the impression that our Unilux rep was disorganized. It turned out he was missing all of the drip caps as well.

Near the end of the first day of installation the guys started installing the kitchen door. Once in place, our Unilux rep went to install the lockset. Something went wrong. He struggled for what seemed like an hour (it may have only been 20 minutes) to get it installed properly. Once he had it installed, he turned and began telling me I would need to remove it to file some parts down to improve the action. For a second time, Tony immediately spoke up, telling me explicitly not to do this, to just use it for a couple of months and it would be fine — which is exactly what happened.

With just my daughter’s bedroom window and the two basement windows left to install, the guys came back the following morning for a couple of hours to finish up. The Unilux rep showed up the second day, dropping some drip caps and the basement handles on a table for me to install. This annoyed me since I had never installed either, and it would’ve taken the Unilux rep a few minutes to do it himself while the guys were working.

And then later, as everyone was leaving, our Unilux rep suggested now that I had seen the guys install the kitchen door surely I’d be fine installing the front door on my own (these Passive House doors are heavy, and ideally require 2-3 guys to install them safely — and preferably by someone who has done it before). They’re also expensive, as I noted earlier, so why would I even contemplate installing it on my own. For a third time Tony probably saw a look of terror on my face, immediately spoke up, and offered to come back to install the front door once we were ready for it.

By chance, Tony somehow managed to be standing next to me each time our Unilux rep made an asinine suggestion. I can’t put into words how grateful I am that Tony spoke up for me and, really, the integrity of our build — he certainly didn’t have to, which probably tells you all you need to know about the quality of his character.

Happy to just have all my windows and kitchen door in, and knowing that Riggs and the  guys were willing to come back to install the front door, I said nothing to our Unilux rep about his behavior.

Later that week, however, we received the Unilux rep’s final invoice. It showed that he was double billing us for job site delivery. It was for just over $300. Not the end of the world, and an easy fix, but, nevertheless, annoying since it seemed to suggest he sent us a final invoice without consulting the original contract.

The invoice also had a storage fee for $1500. He had mentioned months before in an earlier email, after we had just fired our two GC’s, that storage fees were a possibility. At that time we had a lot going on, so I didn’t consult the contract we had signed with him. I just assumed storage fees were in the details of the contract, so when I got the final invoice I planned to pay for it.

But then my wife’s cousin found out about the storage fees, and he expressed surprise, telling us that, in his opinion, no one in the industry does this.

So I went back and looked at the contract. Not a word about potential storage fees. Nothing about when storage fees would begin to accrue, and no fee schedule noting how much per day, week, or month. In an industry plagued by delays, if storage fees were a legitimate billable cost shouldn’t our Unilux rep have the details outlined in his contract?

So then I separately asked a couple of people who work in the construction industry about our situation, one with over 30 years in residential work, the other with over 20 years in commercial construction. They, unsurprisingly, had similar responses:

“What’s in the contract?”

“Nothing.”

“Well, then…”

The one who works in commercial construction was much more blunt:

“So it’s bullshit. He made it up.”

My wife wrote an email to our Unilux rep asking about the double billing for job site delivery and the storage fees, and expressing frustration with how he behaved on the job site during the installation. He responded with a series of emails that can best be described as unhinged or histrionic.

We contacted people above our Unilux rep to see if someone else could come back to finish things up — in addition to installing the front door, a piece of glass broke during installation (we think it was a manufacturing error in the glass), and a different subcontractor broke a part on a basement window that needed to be replaced. They told us our rep was the only one available in the Chicago area, probably, in part I’m guessing, because they wanted our Unilux rep to resolve the situation. Unfortunately, that didn’t happen.

He came back to the site to see the broken part on the basement window, removing the working stay arm (I assumed to make it easier for him to order the correct part, which was a cylinder on the frame that attached to the stay arm). He also dropped off the rest of the missing drip caps and the rest of our correct handles.

broken:missing cylinder on base wdw
Missing cylinder on the frame had been snapped off by a subcontractor.

A few months after this, in November, after drywall had started, the Unilux rep came back to install the replacement glass for the broken window, and the part for the basement window. He was visibly angry and petulant, clearly still annoyed that we had complained about him.

normal basement window
Here’s our other working basement window for comparison. 

When we were in the basement he just handed me the working stay arm that he had removed months earlier, apparently for me to install myself. When I pointed out that he hadn’t given me the part for the frame — the actual part that had been broken and needed replacing — he just stared at the open basement window for a few long seconds before we both realized he had failed to order the correct part.

It had been almost six months since I originally requested the part. Making matters worse, he told me from the outset that the window was unsafe to use until the part had been replaced, so we had never had use of this window since its installation.

He also asked if I had the Unilux owner’s manual. No, I didn’t. He never gave me one. I didn’t know one existed. Why he didn’t give me one the first day of installation back in June, or frankly prior to installation, via email, I’ll never know. Instead, I received the owner’s manual nearly 6 months after the windows had been installed.

The owner’s manual emphasizes how important it is that the windows be opened for at least 30 minutes 3 times a day for “forced ventilation” while drywallers are mudding to ensure no moisture damage occurs to the wood on the windows. If he hadn’t happened to be on site while the drywall guys were present, odds are I never would have received this information, thereby putting the long-term integrity of our windows at risk.

And if there had been damage, then what? Replace the sashes? Replace sashes and frames (the entire window units)? Who would’ve paid for it?

Bob Riggs, his son Brian, and Jason from JPK Builders, came back a few weeks after this to install the front door without our Unilux rep present (I didn’t want him near my house again, I think for obvious reasons). The lockset for the front door was installed without incident. In fact, it happened so quickly I didn’t even see them do it. Clearly there’s nothing inherently difficult about installing Unilux locksets.

We couldn’t be happier with Bob and all the guys he brought to the job site. They work hard, they’re detail-oriented, they’re willing to learn new ideas and techniques, and they have excellent communication skills — not to mention a high level of integrity. We wouldn’t hesitate to recommend Bob or JPK to family or friends. They were a pleasure to have on site, and they were very easy to work with. All of which begs the question: Why doesn’t Unilux recruit someone like Bob to sell and install their windows and doors? He’s used to selling his services anyway, and he has all the necessary construction knowledge to properly install high performance windows and doors. It seems like it would benefit both parties.

A few more months go by, it’s the end of June, 2018, and I still hear nothing about the missing part for my basement window, even though our Unilux rep had assured me in an email back in November, 2017 that he would make sure to order it and send it to me. We couldn’t use the basement window for almost a year at this point.

Reluctant to contact our Unilux rep again, I looked around on GBA and found Hawkeye Windows and Doors out of Iowa who installs Unilux windows. I spoke with Larry Martin, the owner, but it turns out he doesn’t sell Unilux windows anymore. Nevertheless, after I explain my predicament, he’s nice enough to offer to hunt down the same, or similar, Roto hardware part for me.

Within a week or two I have the part in my hand. Think about that for a second. I wasn’t even really his customer. It would’ve been so easy for him to just say no, he can’t help me. Instead, he invested time hunting down this random, miscellaneous part for me. I got better customer service from Larry for a $50 part than I did from our own Unilux rep after ordering a whole house worth of windows and doors. It’s astounding in a way, and what a world of difference from a client’s perspective.

During construction it feels like a miracle when you run across people like Bob Riggs, Tony, or Larry Martin — especially after having to deal with someone like our Unilux rep who needlessly made life difficult for us.

Unfortunately, when I go to install the part, although it could work, I realize it would require drilling new holes in the sash and frame. At that point, I get angry again: Why should I have to drill new holes in a brand new window simply because my Unilux rep is too lazy or incompetent to get me the right part?

I contact a couple of people above our Unilux rep, but I don’t hear back from them right away (one was out of town at the time), so I think I have no choice but to contact our Unilux rep again.

Here’s how our Unilux rep chose to respond to my email, carbon copying me and Eric Murray, the East Coast Regional Manager for Unilux:

“They broke this part after the installation; I had ordered one but then lost it [emphasis added].  According to what you mentioned to me a month ago.  I’ve thought Eric Whetzel was so upset with me after all ( despite all my goodwill , hard work and honesty trying to stay with them in good terms….it has been such an unfortunate experience with these clients; it never happened to me during my entire 30 year career…) I don’t understand why is he still speaking with me if he didn’t want to deal with me again? Anyway, if you did not order this yet, I will have Helmut ship directly to them and done with it”

It’s true, we wanted nothing to do with him, and I think for legitimate reasons. But what’s also true is that after more than a year he still hadn’t gotten me the part for my basement window — either out of malice, incompetence, or some mixture thereof. In addition, he claims to have ordered the part, lost it… and then what? He chose to do nothing? Unbelievable.

After this last email from our Unilux rep, he did, in fact, order the part for me, but when it arrived it turned out to be the wrong part, so it was totally incompatible with my window — wasting everyone’s time yet again.

Eventually, Eric Murray and George Wright from Unilux were nice enough to get me the part that I needed, although I’m sure they have better things to do with their time.

Just as a quick summary regarding our Unilux rep:

  • He ordered window sills with the wrong dimensions (wrong by almost 3″), even though I supplied him with construction drawings so he could get this measurement right. And his proposed solution to this problem ignored our construction drawings and what we were trying to accomplish with an “innie” window placement.
  • He didn’t bring most of the handles we had ordered to site. He never found the missing ones, so he had to re-order them.
  • He didn’t bring the drip caps.
  • He almost broke the lockset to our kitchen door, and then told me to remove it and file parts of it down to improve its action. Tony had to interject and explain why this was inappropriate.
  • He installed most of our Suntuitive glass upside down (4 out of 6 units).
  • He suggested I should install my $5,000 front door on my own.
  • He failed to give me the Unilux window and door owner’s manual, putting the integrity of our windows and doors at risk as drywall was being installed.
  • He tried to double bill us for job site delivery of the windows and doors.
  • He was going to charge us $1,500 for storage fees even though the contract says nothing about potential storage fees.

Obviously some of these items on their own would be no big deal, but when considered together what other conclusion is there but that this person is disorganized and can’t be bothered to get details right (this is the nicest way to interpret his behavior). This seems like an awful lot to get wrong for someone who was on the job site for only a day and a half.

The whole situation is unfortunate, as I explained to George Wright in an email, since we really like our windows and doors. Apart from an adjustment required on our front door and a kitchen window, they’ve been wonderful to live with. They’re beautiful to look at, and they function really well. All of this is undermined by the actions of our Unilux sales rep.

Of all the trades and services we knew we’d have to hire for our build, our Passive House window and door supplier was the last one we expected to have issues develop with customer service.

Suntuitive Glass Performance

Bob Riggs and the guys installed the windows with the Suntuitive glass at an ideal time of the year (June, 2017), just heading into the hottest and sunniest weeks of the year for us here in the Chicago area. It immediately gave us an opportunity to see what the glass can do, and how it behaves on a daily basis.

exterior view of Suntuitive in the evening
Suntuitive installed for our west facade.

It took a couple of days to get used to the colored tint, but we don’t even notice it anymore. It’s a subtle, beautiful gray that goes well with our charred cedar siding (more on that later).

We quickly realized how well the glass works in direct summer sunlight. The picture above doesn’t really tell you much, but in the picture below you can see just how deep the tinting gets when someone who’s standing in the middle of the window puts their arm out of an open side window. The Suntuitive glass really is like sunglasses for a structure.

suntuitive hand in open window
The Suntuitive glass almost looks black from the outside when the sunlight is hitting it directly.

And even when it’s at its darkest, it doesn’t take long for it to go clear once the sun begins to set:

Suntuitive at sunset as tint fades
Evening, and the Suntuitive glass is going clear before nightfall.

And you get a real sense of just how effective the tinting is when you stand inside and look out between a picture window and an open window:

side by side suntuitive and sun
Side by side comparison: Suntuitive vs. direct sunlight.

Here are some more photos of the Suntuitive looking out from the interior:

Suntuitive at full tint in afternoon looking out Family Rm window

Even in the hottest sunlight, the interior side of the glass only warms slightly. It’s a really impressive product.

Suntuitive MBR-Family Rm at full tint in afternoon

Another view of the Suntuitive going clear in the evening:

Suntuitive at sunset looking into backyard
Suntuitive later in the evening, as it turns clear.

In the picture below you can see the glass beginning to tint even though the sun hasn’t quite made it into the backyard to hit the Suntuitive directly from the west. Because the tinting isn’t automatic, its effect is subtle and feels natural as it changes.

me taping family rm wdw from int
Suntuitive glass starting to tint.

With most of the windows and doors installed, I could start thinking about installing my ERV and ductless mini-split system, planning for my first blower door test, and scheduling the install of our siding.

It felt like a really big step in the build — and it meant no more blue tarps covering the window openings to keep the rain out.

Although the days were long, it helped having my wife and daughter on the job site all the time. It also gave my daughter a once in a lifetime chance to play on an active construction site, and she had a blast.

John Ford - beast running away
 A John Ford “Searchers” shot of the Beast running off to play.

It’s been fun to mark progress in the build through photos. In fact, looking through photos sometimes produces real surprises:

beast-looking-at-view-from-br-for-1st-time-close-up
In late January, 2017, looking out the rough opening for her bedroom window…
looking out beast's br window for 1st time
Same opening in June, 2017. A really big moment in the build: getting their first look out of my daughter’s bedroom window.

Six months had gone by, and we had already survived a lot, with much more to come.

Attic Insulation

2

For high-performance structures relatively high R-values for insulation (at least when compared to current building code requirements) are required from the foundation all the way up to the attic (e.g. Passive House or The Pretty Good House).

After some initial research and product pricing, we knew we were going to predominantly use Roxul (with its recent name change, it’s now known as Rockwool) for our insulation needs. But after realizing blown-in rock wool wasn’t available (at least at the time anyway — presumably this will change in the future), and that batts didn’t make much sense for this application (too costly, and they’re considered more difficult to install properly), we knew we wanted some kind of blown-in insulation. The main options, currently, are fiberglass and cellulose.

Fiberglass vs. Cellulose
Best Attic Insulation

We wanted to avoid foam as much as possible throughout the build, both because of its  environmental impact and the fire risk associated with its use, so we didn’t consider spray foam as a real potential option.

After evaluating blown-in fiberglass and cellulose, we decided that cellulose made the most sense for us.

The next decision was to figure out how much, meaning how many inches did we want to blow into the attic. Our first builder was going to do R-49, which is the current code minimum standard here in Illinois. At the time, even before things went horribly wrong with this builder, this felt like too little. I had read stories about other Passive House projects using significantly more, but many of these were in even colder climates than ours (we’re in climate Zone 5 here in the suburbs of Chicago).

How much do I need?
How much insulation is enough?

We decided that rather than settle on a hard R-value as our goal, we would just do a solid two feet of cellulose since we would be doing the installation of the material ourselves (less out near the 12″ raised heel trusses on the north and south sides of the house). There wasn’t a significantly greater cost in materials to go from an R-49 (just under 15″) to the approximately 24″ we blew into the attic.

After doing a little research, and speaking with a Passive House consultant and a local general contractor who consulted with us on various issues as they arose, the consensus seemed to be that attic insulation was an easy, relatively inexpensive place to sneak in more R-value, which is particularly beneficial in our predominantly cold weather climate (the ceiling/attic is where a significant amount of conditioned air wants to escape in the winter anyway). The blown-in cellulose, like the Rockwool, also has some nice sound deadening qualities as an additional benefit.

How much insulation do you need for Passive House?

The cellulose brand in our local Home Depot is GreenFiber, so that was the product we ended up using. Their product is DIY friendly, even allowing homeowners to rent machines for the actual installation:

We started out with 200 bags delivered to the job site. We assumed we were going to need more (the GreenFiber insulation calculator suggested we would need 250 bags to reach 2′ throughout the attic), but thought it might be easier to estimate a final total once the first 200 bags were installed.

The boys, who helped us with various grunt work chores throughout the project, were nice enough to return and help us bring the bags of insulation indoors the night before we started the installation in the attic. We set up a bucket brigade between the driveway and the kitchen, so it went pretty quickly.

guys w: cellulose
The boys after helping us bring in the first 200 bags of cellulose insulation: Luke, Smitty, Eduardo, my wife Anita, and Ricky.

On the day of installation, getting everything set up and started was fairly straightforward. Apart from a loose hose connection at the machine, which a small strip of Tescon Vana tape rectified, we had no issues with the blower. While my wife fed the bags of cellulose into the blower, I was up in the attic directing it into place.

The first couple of hours were actually kind of fun, but getting a consistent two feet of insulation throughout the attic was time consuming and eventually mind-numbingly boring. The first 12″-18″ weren’t so bad, it was having to wait in each section of the attic for that last foot or so to be blown in place that it began to feel like real drudgery.

cellulose installed looking east
From the attic opening, looking east towards the front of the house.

It also didn’t help that I had a fever and a cold on the day of installation, so being up in the attic surrounded and covered in dust didn’t improve my mood. The process, although very DIY friendly, does require patience and a willingness to cover up — eyes, mouth, and nose — for adequate protection against all the dust floating around.

The day before blowing in the cellulose I went through the attic and marked my goal of 24″ of insulation on various roof trusses so I would have a good visual goal to shoot for. In fact, had I known just how dusty and challenging visibility was going to be during the blowing process, I would have marked every single roof truss at the 24″ level to make the job a little easier.

We didn’t have much in the way in terms of obstacles from various services, other than a few pipe vents for plumbing and radon, along with a small amount of electrical conduit for solar on the roof and a single light in the attic (we kept the majority of all services in our ceiling service core and our walls). This made for a fairly straightforward installation of the cellulose.

cellulose installed looking west
From the attic opening, looking west towards the back of the house.
south east corner w: cellulose
Another view, this time a little further to the right, showing the far northwest corner of the attic.
vents by bench w: cellulose
Cellulose at its full depth around the plumbing vents and radon stack.
cellulose at the attic hatch
Finishing up. The attic access hatch is visible at the bottom of the photo.
bench behind attic hatch opening
The bench next to the attic access opening as we finish up blowing in the cellulose.
building up cellulose around attic chutes
Cellulose hitting the underside of the insulation chutes as it gets blown into place at the edge of the roof by the raised heel trusses.

Thankfully I was able to keep the cellulose out of the insulation chutes, instead slowly piling it up just below each chute. The siding guys already had most of the soffits installed (this was the end of October, 2017 last year), including a channel for air flow for our “vented roof” assembly, so any cellulose that found its way into the chutes and down into the soffits would’ve been a real pain to remove (I’ll have a separate post later about the siding installation, including the many details of our rain screen and 4″ of Rockwool on the exterior side of the Zip sheathing).

The bench next to the attic access hatch ended up working out really well, and I was very thankful it was in place.

lid on bench w: cellulose
Lid of the attic access hatch sitting on its bench next to the attic opening after the installation of the cellulose is nearly complete.

By the end of the first day it was clear we didn’t have enough cellulose to finish the whole attic. We started with 200 bags, but we finished up the second day at just under 300 bags total (288 was the final number of bags installed, so a little more than the 250 recommended by the GreenFiber calculator). What we didn’t use we were able to return to Home Depot for a refund.

how much more cellulose
My wife wondering how many more bags until we’re done — unfortunately the answer was simply ‘more’ as she popped her head up into the attic several times towards the end of the installation.

Apart from the north and south sides of the attic around the raised heel trusses, we had a solid 24″ throughout the attic, in fact, a little more in the center of the attic where it was easiest to pile it up and let it accumulate (closer to 28-30″ in some areas). This probably explains, too, the additional 38 bags we used that exceeded the initial estimate by the GreenFiber calculator.

covered in cellulose
This is where a degree from Michigan gets you. #GoBlue. It was a long day.

On a side note, there was also some concern about the weight of the cellulose on the Intello (our ceiling air barrier), but in the end, even where the cellulose was at its deepest, there was thankfully very little sagging evident in the Intello. Even if it had been worse, the 1×4’s were in place to help support the Intello and the cellulose for the long term (the 1×4’s were spaced roughly 16″ apart between the 2×6’s of the service core).

sag1
Slight sag in the Intello evident after installing the cellulose in the attic.
sag2 closer view
Close-up of the slight sag in the Intello near the west gable end of the house.
sag3 Intello touching 1x4's
Another view of the slight sag in the Intello as it touches the 1×4’s directly below it.

It’s worth keeping in mind that the cellulose will settle a bit, especially during the first few months. This is obviously very important when it comes to establishing what depth you’re initially going to blow in and your expectations about long-term R-value after settling has occurred (something to consider before signing a contract if you’re going to be hiring someone to do the work — both parties should agree and understand what the final R-value will be before the work commences).

I was back up in the attic recently as I finished up painting the master bedroom and closet. Since I already had drop cloths down, I thought I should take what will hopefully be one last look at the attic.

ladder in wic
Ladder under the attic access hatch in the master bedroom closet.

On average, the cellulose looks like it has settled about 2-4 inches below its original depth, depending on where I looked.

settling1
Some of the red horizontal lines at 24″ now clearly visible in some parts of the attic.

Even with this settling, the attic probably still comes in close to R-70 on average —significantly less out at the north and south ends of the roof with the raised heel trusses, but a little more in spots towards the middle of the attic where some red lines are still hidden below the cellulose.

settling2
You can see my red arrow and horizontal line at the 24″ level off to the right.

Just under or over R-70 in the attic is in tune with both the Pretty Good House and Passive House metrics for attic insulation for my climate region (Zone 5 here in the suburbs of Chicago).

While I was up in the attic I also noted that there was no evidence of any water or moisture damage on the OSB roof sheathing, or any indication of wind washing of the cellulose, so the attic seems to be performing as designed, which is a great relief.

WRB: Zip Sheathing (Air Sealing #6 )

2

Sealing the Seams and Penetrations in Zip Sheathing

Note: This post will concentrate on the Zip sheathing itself, as it relates to seams and penetrations. I’ll address how I sealed around openings for windows and doors, along with our attic access hatch through the Intello on the ceiling in separate, future blog posts.

We used Zip sheathing as our WRB (weather resistant barrier — sometimes it’s referred to as a water-resistant barrier) based largely on Hammer and Hand projects:

Also, for years I’d seen it used on various jobs featured in Fine Homebuilding Magazine.

As the 7/16″ Zip sheathing went up, I taped most of the seams with Pro Clima’s  3″ Tescon Vana tape (available at 475 HPBS), but also their Contega tape (6″ wide), which I used mainly for outside corners and larger seams in the Zip (mainly where the horizontal seam in the Zip transitioned from the exterior walls of 2×6 framing to the roof trusses — shown in a photo later in this post).

My wife and daughter also cut up the Tescon Vana tape into small pieces in order to cover all the nail and screw holes in the Zip sheathing.

beast and eduardo taping nail holes
The Beast and Eduardo team up to tape the nail and screw holes on the lower sections of Zip sheathing around the house.

The nail holes were initially sealed with HF Sealant, also available from 475 HPBS, thus giving them double coverage — this was discussed earlier, here:

Framing (Air Sealing #2)
north side house garage gap long view
Northeast corner of the house where it meets the garage.

Our decision to use the Zip sheathing was also discussed earlier, here:

Wall Assembly

And here’s a good video discussing the Zip sheathing and its benefits (and its place in the evolution of building science):

If I had it to do over, I think I might be tempted to use 1/2″ exterior grade plywood as my sheathing (there are any number of WRB options these days). This would be sealed on the exterior side with either a liquid membrane, like Prosoco’s Cat 5, or a peel-n-stick tape like Henry’s Blue Skinor even another 475 HPBS product Solitex Mento 1000.

The Zip sheathing works, and the exterior green skin held up nicely during construction, even as it sat exposed for nearly 10 months after we fired our GC’s and struggled to keep the project moving forward. Nevertheless, it is little more than glorified OSB, which comes with certain inherent weaknesses.

Matt Risinger does an excellent job of delineating the cost/benefits of using either OSB or CDX plywood as a sheathing material:

house-garage-gap-for-4%22-roxul
Garage (at left) house (at right) connection. Gap will eventually be filled with 4″ of Roxul Comfortboard 80.
garage-house-gap-2
Closer view of this same garage – house connection. Flashing will cover the bottom of the Zip and then carry over the top of the Roxul that covers the foundation.
north-side-seams-taped
View of the north side of the house as Tescon Vana tape air seals the nail holes and the seams in the Zip sheathing.

View of the West facade with Tescon Vana tape, along with the black Contega tape at larger seams (e.g. where the walls meet the roof trusses) and outside corners.

west side being taped
West facade as taping proceeds.
taping north side before mechanicals : windows
Northwest corner of the house, transitioning from the Tescon Vana to the black Contega tape at the corner.
finishing up seams on west facade
Finishing up some of the final seams in the Zip on the West facade.

Once the Zip was fully installed, it was readily apparent that some of the seams, especially near the base of the first floor where a horizontal seam ran around the entire structure, would need to be tightened up.

Here’s a view looking down on one of these areas where the Zip sheathing did not sit flat against the framing members:

down Zip - out of alignment before 1x4's
Horizontal seam in Zip sheathing refusing to lie flat against the 2×6 framing members.

Using a 1×4 in each stud bay, I was able to pull the seam in the Zip sheathing together. It wasn’t always perfect, but the difference was visibly significant and in most areas well worth the effort.

Placing a 1×4 into position over the seam in the Zip, I would drive a couple of screws towards the exterior.

1x4 in study bay before HF
1×4 used to pull an unruly seam in the Zip sheathing together.
screw thru zip for 1x4 in stud bay
Screw from the interior poking outside as it initially gets the 1×4 in place.

Once securely attached from the interior, I went outside and drove several screws into the Zip, both above and below the seam in the Zip, to pull the seam tight to the 1×4. At that point, I could go back inside and remove the two screws that were driven towards the exterior.

In addition to air sealing the exterior side of the Zip sheathing, I also invested some time in air sealing the interior side of the Zip as well. Below is a long view of several stud bays with 1×4’s installed, but before air sealing gaps around the 1×4’s and lower areas of the stud bays with HF Sealant.

stud bays w: 1x4's, before HF

Long view after applying the HF Sealant:

ceiling walls - HF Sealant

Close-up of the interior side of the Zip sheathing meeting a 2×6 framing member in a stud bay after applying a thick bead of HF Sealant:

thick bead HF sealant in stud bay

Close-up of lower area of a stud bay after air sealing with the HF Sealant (it transitions from a light to darker green as it dries):

stud bay w: 1x4 and HF sealant
1×4 installed and HF sealant applied to all gaps and screw/nail holes in the stud bay.

I held off on using the HF Sealant at the wall sill plate/subfloor connection until just prior to installing the Intello on the walls since this area constantly attracts dirt and debris.

Sealing on the interior side with HF Sealant, even between vertical framing members, means that even if there are any weaknesses in either the Zip sheathing or the Tescon Vana tape at these points, air won’t find an easy way in, since it will be blocked from the interior side as well (there won’t be a difference in air pressure to help the outdoor air make its way indoors).

This kind of redundancy in air sealing should give the house long-term protection against air leaks, thereby aiding the long-term durability of the structure, as well as making it a much more comfortable environment to live in.

interior walls sealed w: HF sealant
Using HF Sealant between vertical framing members.

I also spent some time on the roof trusses, sealing around nails, the top plates of the exterior walls, and the many Zip-framing member connections in what will eventually be the attic.

sitting on roof trusses sealing
Sealing around fasteners and framing in the attic with HF Sealant.

This had less to do with air sealing and more to do with preventing any potential water intrusion since this area is technically above our ceiling air barrier (the Intello), which is detailed here:

Ceiling Details (Air Sealing #4)

Inventory of Penetrations through the Zip Air Barrier

I made a mock wall assembly before construction began, which I discussed here:

Wall Assembly

This proved helpful when explaining to the various subs how to help me protect the air barrier — especially when it came time to drill holes through the Zip sheathing. Of particular importance was making holes closer to the center of a stud bay, as opposed to hugging a corner or side of one of the 2×6 framing members. A hole cut too close to a stud or a roof truss is much harder to properly air seal.

bad-good-mock-wall-assembly-for-penetrations
Interior side of our mock wall assembly showing how all penetrations through the Zip should be in the middle of our framing members. Our original plumber was the only trade that managed to screw this up (it’s no coincidence that he was also the only sub that we had to fire).

In effect, any time a sub had to make a penetration through the air barrier we discussed the details, and once the cut was made I immediately air sealed the penetration both on the exterior and interior side.

By sealing each hole in the Zip on both sides, again I hope it ensures the long-term durability of the overall structure. The main argument for this strategy assumes the exterior side of the sheathing will face more extreme temperatures, and fluctuations in humidity, and presumably even wind-drive rain if/when it gets past the siding and 4″ of Roxul insulation, putting it at greater risk of failure (especially in the long term). By taking the time to air seal the interior side, it just gives the overall air barrier, and therefore the structure, a better chance at avoiding air and water intrusion (that’s the goal anyway).

For air sealing I used a mix of tapes, HF sealant (later even some Prosoco products), EPDM Roflex gaskets, and duct seal.

The penetrations for electric service were my first go at using the Roflex gaskets:

John & Donny installing meter
John and Danny installing the electric meter.

The smaller diameter Roflex gasket comes with its own Tescon Vana tape, which makes installation straightforward.

close up meter thru Zip w: TVana gaskets
Electric meter with Tescon Vana – Roflex gaskets installed.
meter - hole, t. vana prior to appl.

Exterior view of electric Meter air sealed with gaskets and Tescon Vana tape:

electric meter close up gasket : t. vana

Once sealed on the exterior side, I went inside to seal the penetrations for a second time:

meter to panel - interior
Air sealing the electric meter on the interior side.

It was a big moment when the electric panel went in:

main panel in - progress
The house is ready for power.

The installation of our solar panels required air sealing two penetrations — one through the Intello on the ceiling on the inside of the structure, along with one exterior penetration through the Zip:

Details regarding the installation of our Solar array can be found here:

Solar on the Roof
corrected solar on:off
Solar disconnect (on/off) with its Tescon Vana gasket.

We also had two frost-free hose bibs, or sill cocks, installed, which also required gaskets on the exterior and interior sides of the Zip sheathing.

hosebib w: gasket
Frost free hose bib with gasket.

One of the big advantages a Roflex gasket has over using a sealant like the green HF Sealant, or Prosoco’s Joint and Seam, is the pipe can be moved in and out even after air sealing, which is especially helpful for installing siding later.

We left the sill cocks loose (unconnected to water supply line inside the house), allowing the siding guys to adjust in and out for a more precise fit of the charred cedar siding.

Below is an example of what conduit through the Zip sheathing looks like before it gets a gasket and some tape:

exterior light conduit before gasket
Penetration for conduit before gasket.

And here’s the conduit after the gasket and some tape:

gasket for exterior light
Conduit after gasket.

Note the extended length of the conduit, anticipating our 4″ of Roxul covering the Zip, 2-layers of furring strips (vertical then horizontal — for vertically oriented siding), and the eventual charred cedar siding.

The photo below shows the penetrations, along with multiple lines of conduit, for our eventual ductless mini-split Mitsubishi heat pump system. The empty hole will be our disconnect for the heat pump. I’ll go into the details of our ductless mini-split system in a future post.

conduit for heat pumps
Penetrations for our Mitsubishi heat pump system.

Same series of conduit pipes after gaskets and being connected to the compressor outside:

heat pump electric w: t. vana before disconnect

In addition to the conduit for electrical hook-up, the Mitsubishi heat pump system required a separate penetration for running the refrigerant lines to the compressor:

hole in Zip for heat pump pvc
Hole cut for the heat pump refrigerant lines.

After discussing it with Mike from Compass Heating and Air, who did our ductless mini-split installation, we decided to use a 4″ section of PVC plumbing pipe as our “conduit” for running the refrigerant lines from the interior of the structure to the outside:

heat pump - pvc pipe in hole for lines
4″ PVC plumbing pipe for the refrigerant lines.

After the PVC was passed through the hole in the Zip, we added a 2×4 underneath it to give it some added stability, along with the usual gasket and tape for air sealing around the PVC pipe:

heat pump - int side - pvc, gasket, 2x4
Before applying Tescon Vana around the Roflex gasket.

Once the refrigerant lines were passed through the PVC pipe, it was clear that some additional air sealing was required.

gaps around pvc lines before duct seal
PVC pipe with refrigerant lines installed.

I filled the gaps around the refrigerant lines from the interior and exterior sides with duct seal. Before stuffing in the duct seal at either end of the PVC pipe, I added bits of Roxul Comfortboard 80 into the pipe to try and give added R-value to the interior of the PVC pipe (hoping to prevent any possible condensation from forming inside the pipe).

duct seal label
A real lifesaver when it comes to air sealing. Readily available at big box stores, or online at Amazon.

Duct seal proved especially helpful at air sealing multiple weak points in the structure —areas that would’ve been difficult or impossible to air seal with just tape, gaskets, or sealants:

heat pump pvc w: duct seal close up interior
Using duct seal to block off air from the interior side.
heat pump pvc w: gasket before t. vana close up
Another view of the PVC pipe with duct seal.
heat pump refrigerant lines - int. leaving basement
The refrigerant lines transitioning from the basement ceiling to the PVC pipe before leaving the structure.

Once the interior was taken care of, I was able to address the exterior side of the PVC pipe:

heat pump lines before tape after duct seal
Exterior view of the PVC pipe with heat pump refrigerant lines exiting the structure. Air sealed with a Roflex gasket and duct seal inside the pipe.

Again, note that the PVC pipe is extended out in preparation for the layers of exterior insulation, furring strips, and siding:

heat pump lines leaving house - sealed
Same area after completing the air sealing with Tescon Vana tape.

And here’s a view of the same area after the siding was installed (I’ll go into the many details regarding the installation of the exterior insulation, furring strips, and siding in a future post):

Heat pump lines w: duct seal and siding
Air sealing for the refrigerant lines complete after the siding is installed.

Additional areas where the duct seal proved to be invaluable:

close up exterior outlet box w: duct seal
Exterior electrical boxes for lights and outlets.

Conduit for the water meter in the basement (only the interior is shown below, but the conduit was air sealed with duct seal on the exterior end as well):

And here’s the same conduit for the water meter as it leaves the house on the first floor:

conduit for water meter sealed w: tape:gasket
Conduit for the water meter, air sealed on both sides of the Zip with the Roflex/Tescon Vana gasket.

I also had to address the disconnect boxes for our solar array and our heat pump. For instance, here’s our solar disconnect box when it’s open:

solar disconnect before removing

And here it is after removing the pull out switch, revealing an air leak:

solar disconnect before duct seal

Close-up of the conduit:

close up solar disconnect before duct seal

An even closer look:

close up penetration in solar box before duct seal

And here it is after being air sealed with the duct seal:

close up solar box after duct seal

I did the same air sealing for the Mitsubishi heat pump disconnect box:

heat pump box before removing

Close-up of the conduit sealed with the duct seal:

close up penetration in heat pump box w: duct seal

During my initial blower door test (more on that later), some air movement around the main panel in the basement was detected, so when the electrician came back we added duct seal to the main pipe entering the house (it had already been sealed from the exterior side with duct seal):

main panel - interior - duct seal
Close-up view of the main panel from the interior where lines first enter the structure.

Besides the penetrations in the Zip sheathing, there were other penetrations through the Intello (our air barrier on the ceiling) that had to be addressed as well. These areas were air sealed with the same set of products as the Zip.

For example, in addition to the conduit for solar through the Intello, we also had to air seal conduit for electric service to the attic (for a light and switch in the attic), in addition to the the penetrations for radon and plumbing waste vents, some of which are shown below:

plumbing vent thru Intello gasket:t. vana
Plumbing waste vent going into the attic.

Another view of this vent pipe after air sealing, this time from below:

sealed plumbing vent from below

Here is one of the vents that our first, incompetent plumber installed too close to one of the 2×6’s used to establish our service core:

plumbing vent installed too close to 2x6
Installed this close to framing makes air sealing the vent needlessly complicated and frustrating.

Here’s the same area after applying the Tescon Vana tape:

plumbing vent too close to 2x6 sealed w: tape

Below is another vent pipe incorrectly installed too close to a 2×6. This one was even more challenging to air seal properly. After the gasket and Tescon Vana, I added the green HF sealant as insurance against air leaks, both for now and in the future.

vent too close w: sealant too

We also had to air seal the penetrations for our Zehnder Comfo-Air 350 ERV ventilation unit. I’ll go into the details of the actual installation later, but here are some photos of the penetrations through the Zip sheathing and how we addressed making them air tight:

ext - comfo pipe going thru zip into basement
First section of Comfo pipe going through the Zip sheathing.
Zehnder tube exiting w: gasket
The gray Zehnder Comfo pipe (for supply air stream) exiting the structure with a Roflex gasket.
Zehnder pipe sealed w: gasket and tape
Closer view of the Comfo pipe air sealed with a gasket and Tescon Vana tape.
close up Zehnder Comfo Pipe w: gasket and t. vana
An even closer view of this same area where pipe meets gasket and tape.

We followed the same process — Roflex gasket and Tescon Vana tape — for the exterior side of the Zehnder Comfo pipe:

ext Zehnder gasket : t. vana
Zehnder Comfo pipe installed, air sealed, and ready for commissioning.

And here’s a picture of both supply and exhaust pipes for the Zehnder:

Zehnder exhaust and supply pipes ext fully sealed
Supply pipe in the background, exhaust in the foreground. The garbage bags keep out weather and animals until after the siding is up and the permanent covers can be installed.

During my initial blower door test some air movement around the sump pit was detected.

sump pit air sealed
Sump pit lid sealed with duct seal, Roflex gasket with Tescon Vana, and the seam between the pit and lid sealed with Prosoco Air Dam.

The sump pump discharge pipe also needed to be air sealed on both sides of the Zip:

sump discharge pipe w: gasket and joint and seam
Sump discharge pipe sealed first with Prosoco Joint and Seam, then a Roflex gasket, before applying Tescon Vana tape around the gasket.

Some air movement around the ejector pit was also detected, so I used duct seal to try and block it.

ejector pit air sealed with duct seal
Ejector pit air sealed with duct seal.

For low voltage — in our case, a cable TV/Internet connection — we found a utility box at Lowe’s (also available at Home Depot and Amazon), and combined it with conduit to transition from the exterior to the interior. The diameter of the conduit is large enough to allow wires for other utilities/services to pass through as well, if necessary, in the future.