kimchi & kraut

Passive House + Net Zero Energy + Permaculture Yard

Tag Archives: green homebuilding

Passive Solar: The Beauty of Light

4

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.

Flooring: Basement Paint Splatter

0

The Original Plan

We didn’t want to spend a lot of money on basement flooring, so we knew we wanted to keep things simple, especially since we weren’t going for a high-end look for the space. The basement is mostly unfinished, at least by traditional standards. We use the space mainly for working out, reading, office work, some smaller arts and crafts projects, and we’ve created a few small areas for miscellaneous storage.

Whatever we came up with had to be durable, if only to avoid having to replace any flooring should the basement ever have a problem with water (e.g. from a failed sump pump or a leaky hot water tank).

The plan initially was to just seal the floor with tung oil, much like we did for our wood floors. I thought if I used a slurry mix to patch some surface imperfections in the concrete beforehand that it might produce a pleasant mottled look across the entire floor once it was finished with the tung oil.

Unfortunately, once this patching was done, it quickly became apparent that the look was just messy, if not just boring and forgettable. Even tinting the slurry mix to various shades of blue and green didn’t seem to help at all.

base after patches b4 tung
Basement slab ready for tung oil finish.

With the patching complete, I went ahead and did the tung oil application just to get rid of the constant concrete dust on the surface of the basement floor.

base b4 after tung
Tung oil just applied on the left, darkening the concrete as it seals it.

I applied it the same way I did for the hardwood flooring on the main level. I also broke it up into sections, using the preformed contraction joints in the concrete slab as a guide.

base section w: tung
Tung oil applied, waiting for it to soak in before applying it again to any ‘dry’ spots.

I knew I’d have several months while other projects were being finished upstairs to figure out another solution.

close-up corner base tung

An even closer view after the tung oil has been applied:

base tung oil
Concrete mostly dry; ready to wipe down any excess tung oil remaining on the surface.

Jackson Pollock as Inspiration

After almost a year had passed, and with much of the work on the first floor finally complete, it was time to come back and finish up the basement floor.

My first thought was to use the painting techniques of Jackson Pollock as an inspiration.

After looking through online photo galleries of his work and watching some videos, I realized I’d forgotten just how layered much of his work is.

It was while researching his work that I also came across an East Coast (mainly New York?) beach house tradition of splatter painting floors, done mainly, it seems, to hide the sand and mess brought in from the beach, all while giving the floors some added durability.

We decided we’d try to mimic some of Pollock’s technique, but do it in lighter layers so more of the tung oiled concrete could show through.

Since it was too cold at the time to have Green Building Supply ship me all of the paint required, we decided to take a trip to Madison, Wisconsin for the weekend to pick up the remainder of what I needed from Premier Paint and Wallpaper.

Premier is a really nice family-owned independent paint store with a wide variety of brands and products. The paint stores around us are exclusively national chains like Sherwin Williams, Benjamin Moore, or PPG. When you walk into these stores you definitely feel the difference compared to a mom and pop operation.

Premier mixed up what we needed, and we were off to enjoy the rest of our weekend in Madison where there’s always something to do outdoors, and there’s no shortage of great restaurants, like Sal’s Tomato Pies:

sal's

In terms of colors for our splatter technique, we decided to stick with the blue we had used for the basement steel beam and columns, along with white as a neutral color, while finishing with a bright green to liven things up a bit. This combination mimics the iconic color scheme used by Kawasaki motorcycles:

With the walls prepped to prevent overspray from the splatter hitting them, my daughter and I started to experiment in the back corner of the basement with the white color first. We felt like the white color would be the best option as our base coat color, complementing the now tung oil darkened color of the concrete.

base walls prepped
Practicing our technique first with the white concrete paint.

We also took our time to experiment with the other colors, figuring out exactly how we wanted the paint to fall on the concrete — either in droplets or in long, stringy patterns.

experimenting w: each color
Testing out the blue and green paint colors.

Based on this first section, we felt like we could go fairly heavy with the white and still have some of the darker tones of the concrete underneath come through the final finish. In each section we first started with the white to establish a base coat to work off of for the subsequent applications of the blue and then green.

base white going down
This section is ready for the blue and green.

We then played around with how much blue and green we wanted to finish up with on top of the white and the darker concrete underneath.

experimenting more blue
Experimenting with how much blue and green we should use.

Here’s one of the first completed areas around a steel post or lally column:

basement pole
It was exciting to see the colors finally come together to such vivid effect.

A second view of a completed area, this time out in the middle of the floor:

base 3 colors done

As we finished up a section, we would start to sort through the remaining moving boxes and put together each space more permanently. It was also a good opportunity to further purge anything still in boxes that we didn’t end up needing in our new home.

For one area of books we used the traditional set-up of cinder blocks and wood shelves, but we added some character by taking the time to paint the blocks using the floor colors. We also turned the blocks on their side to hide their empty centers. I had seen this technique used in a YouTube video as a way to dress up this type of shelving normally associated with a college dorm room or one’s first apartment:

It definitely added some time to the project as each block required a couple coats of paint, but it was a nice way for my daughter and I to have some more fun with color, too.

This section of books on cinder blocks helps to close off and define this sitting and reading area from the storage and arts and crafts area behind it.

base setting up space
Getting a section of the basement mostly put together.

We were pleasantly surprised by the wide variety of looks, textures, and playful randomness in the overall pattern of the paint splatter.

another view cinder
A closer view of the painted cinder blocks.

It’s definitely unpredictable to a great degree, but with practice it did become easier to control, and we did develop a feel for how we wanted each area to end up looking.

blk lgt cinder
An even closer view of the cinder blocks, including an unfinished gas pipe ‘robot’ light.
getting white base coat down
Establishing the white base coat in another section before adding the blue and green.

Here are several close-ups showing some of the texture created by the splattered paint, whether as drops or longer, stringy ropes.

splatterd
splattera
splatterc

A wider shot showing the layering of the three colors, with the darkened concrete and some of the slurry patches still visible underneath.

splattere

We weren’t afraid to leave some areas with a lighter application of paint. The mix of light and heavier areas of coverage helps to give the floor visual interest, and it hopefully emphasizes the human element involved in the final look of the finish.

basement spatter close up
An area with lighter coats of paint.

Once the white paint was applied, we would let it dry overnight. The next day we would come back and apply the blue.

base flr lgt bg
Close-up view of a lighter area with the dark concrete still visible underneath.

Since each color would have areas of fairly heavy coverage, after the white was down we always applied the blue and green coats in our socks to avoid even the possibility of our shoes pulling up any areas of uncured paint.

basement spatter in sunlight

Most of the photos show the colors in daylight, with the sun coming through the two basement windows, but we’re equally happy with how the floor looks under artificial light at night.

blue strings
The floor finish under ceiling lights at night.

We typically gave the blue 24 hours to dry as well, although there were a couple of times where we waited only about 6-8 hours before starting the green. With less paint on the floor, it seemed to take the blue less time to sufficiently dry.

The goal was to apply less paint with each change in color. We definitely wanted the white to remain the main background color, with the blue and the green acting as pops of accent color.

base 3 colors done

When the floors had only been sealed with the tung oil, although it solved the concrete dust issue, it did make several areas slippery smooth. Because the paint splatter hits the concrete in various thicknesses, the slightly uneven texture this produces helps make the final finish slip resistant. Even with this high build in some spots it’s never been a problem; instead, this texture is pleasant both underfoot or even to the touch.

I was a little worried about the thicker areas of paint drying and curing properly, but apart from some bubbles that popped as the paint dried, and some areas where the paint film shows some wrinkling on the surface, we had no issues in this regard.

wide shot base spatter

In addition to being slip resistant, it was also a relatively inexpensive finish to create, requiring just 3 gallons of white, 2 gallons of blue, and a single gallon of the green. This was in addition to the initial tung oil and citrus solvent (around 4-5 gallons of each) that we had applied to first seal the concrete. For slightly less than a dollar a square foot, the paint splatter technique produces a unique, one of a kind floor finish.

And the choice of colors is limited only by one’s imagination. We even contemplated adding some stencils that could’ve incorporated numbers, letters or words, or even distinct shapes. Instead, we decided to keep things simple and stick with just the splatter pattern. Nevertheless, there’s no reason not to explore all of these options before settling on a final design.

spatter cu texture
Extreme close-up view of the final finish.

One other key advantage to the paint splatter is that if any part of the floor were to see damage, whether from abrasion or moisture pushing the paint off the concrete, it would be relatively easy to repair with some additional paint applied using the same process.

This would not be the case had we used a single color, cut and rolled the typical way, across the entire basement floor. Any damage, even in a small area, with a single color tends to look horrible, and it would be difficult to correct it without leaving a ‘crater’ look in the area that had peeled and then been repaired.

base paint cans
The products we used for each color of paint splatter.

Premier couldn’t mix the blue in the Safecoat product, so we had to use the Fixall enamel instead. Even though it has more VOC’s than the Safecoat, within a couple of days any noticeable smell had dissipated. It probably helps that the total square footage of blue applied is fairly small.

outside corner
Back corner of the basement office.

At outside walls we ended up letting the paint hit the Air Dam that’s covering the gap between the slab and the foundation wall (there’s rigid foam below this gap acting as a thermal break between the slab and foundation wall).

another outside corner
An outside corner.

Since it was somewhat random how the paint hit this gap, some spots were hit heavily, while most just saw a slight smattering of color in this area.

basement spatter near fdn wall

There were only a couple of spots where the paint splatter managed to get behind or beyond the paper we had taped on the walls to protect them. For those spots it was easy to go back and touch them up with a small brush of wall paint.

spatter at outside wall

In terms of technique, we used paint stirring sticks to apply each color. Depending on the effect we wanted, how we worked our wrist determined the pattern of the paint. For example, if we loaded up the stick with a lot of paint, or even just a little, and we flicked the stick hard — like you would using a fly swatter — you could get a lot of drips and ‘dots’ over the floor. With a lot of paint on the stick you ended up with heavy droplets and spray. With less paint, you still had drops and a spray effect, but the coverage was much lighter over the tung oiled concrete.

This worked great for applying the white base coat when we were trying to get a lot of color on the floor all at once, and at different rates of coverage.

For the blue and the green we again loaded up the stick heavily with paint, but with very little movement of the wrist — just with a slow and deliberate arm motion — we let the paint fall off the stick using slowly undulating half-circles, figure eights, and wave motions.

The photo below shows a corner of the basement office with just the slurry patches and the tung oiled finish. With the walls protected, we could begin laying down the three colors of paint splatter.

office before splatter
Corner of basement office ready for paint splatter.

Here’s the same area after the three colors of paint splatter have been applied:

base closet
Corner of the basement office complete.

And here’s the main area of the basement office as we were finishing up:

basement office complete

And here’s the foot of the basement stairs:

foot of stairs

The final finish is definitely playful and whimsical, bringing a lot of life to the floor through the use of bright, bold splashes of color. With a combination of toned-down colors, I can imagine this splatter technique working even in a space that’s been more traditionally designed and decorated.

apei
Reading and hang out area finally complete.

By staying neutral with the wall color, and by leaving the ceiling unfinished, it keeps the visual emphasis on the floor and the bright blue of the structural beam.

Here’s another view of the reading area:

apeii

A close-up of the floor, along with the concrete lightbulb:

floor w: concrete lightbulb

We managed to sneak in some extra storage by placing smaller books on the steel beam:

beam books

We also added pops of red accents in the basement, something we would continue on the main floor of the house:

red wrench
Found this oversized wrench online.
red lantern
My mom contributed this antique kerosene lantern for use as one of our red accents.
oil burner
This light switch cover seemed nicely ironic for an all-electric home. It also fits in well with our Urban Rustic design scheme.

This chair was our only splurge on new furniture in the house —- an episode of Comedians in Cars Getting Coffee ended with Jerry Seinfeld and Jim Carrey enjoying a good spin:

spun cu

Undoubtedly, a ridiculously expensive chunk of plastic, but worth every penny if you go by the giggles-per-person of those trying it out for the first time:

A revealing test to see if your inner child is still alive and kicking.

redcoffeebrgt
Plates on a decorative piece of concrete. Real coffee beans were embedded in the bottom of the form to create this look, along with dark tung oil applied to the white concrete.

Eventually I’ll get more artwork up on the currently mostly bare concrete walls — it should really help to tie the room together:

big lebowski
Found this poster online.

The paint splatter and tung oil finish has been in place for over a year now. It’s holding up well, even under the friction from the Spun chair wobbling around, or the office chairs and workout bench being slid across the floor.

blue glass arrow
Blue glass embedded in white concrete arrow.

The only thing I would do differently is probably try and find a concrete sealer that’s less expensive than the tung oil and citrus solvent combination.

chinesebeauty1
Chinese ‘beauty’.

Using a different product would require testing it in a small area first for adhesion — both the sealer over the bare concrete and, once the sealer is cured, to make sure that the concrete paint fully adheres to the sealer without any issues. It would take some time to establish this definitively, but well worth the effort in order to avoid any potential issues with peeling paint.

hulk go green

Apart from its relatively easy application and excellent durability, we love the floor finish because it was so much fun to create. While it’s definitely not a formal looking finish, it is a project the whole family could be involved in, regardless of age or ability. And we would gladly do it again if given the chance. We can’t recommend it enough if you’re looking for a fairly inexpensive way to finish a floor in a unique way.

Flooring: Tile

4

Porcelain Tile

We chose porcelain tile mainly for its durability, plus we found a collection of tile that mimics aged concrete, which we felt would work really well with our Urban Rustic theme for the house.

The Iris US Ecocrete collection allowed us to use two different colors while maintaining a consistent overall look through the house. For example, in the kitchen, entry, and utility room we went with the Sage color; a nice mix of green, gray, and even some spots of very dark green or black. For the master bath we went with the Weathered Black since we were going to have some red accents and we wanted to play with color a little bit.

The Ecocrete tiles are also Greenguard certified, and they have a slightly rough surface texture to help prevent slips or falls.

For tile underlayment, Wonderboard Lite was our base.

wonderboard

For thinset and grout, Mapei products were used, readily available from Floor and Decor.

Mapei thinset bags

For our shower walls, we used a newer system from USG, their Durock Glass-Mat backerboard. For the floors we used their pre-sloped shower tray system.

The shower kit also came with all the drain components.

shower drain cover

Colors and Textures

In the photo below, all of our tile selections are laid out in preparation for deciding on grout colors.

The porcelain hexagon tile was used on the floor of our second bathroom, in addition to the floor of each shower. These were the only areas where we didn’t use the Ecocrete tiles.

The blue glass accent tile was used in our second bathroom shower, while the red glass was used in our master bath shower.

The white subway tile was used in both showers for the ceilings and the walls.

tile grout selections

Tile almost complete in the kitchen:

kitchen tile being installed

Tile started in the master bathroom:

mbath floor tile going down

For the two showers we decided to orient the slightly larger than traditional subway tile in a vertical pattern, a subtle repetition of the strong vertical lines of our charred cedar siding.

In the second bathroom shower we used a 4″ x 10″ subway tile, while in the master shower we went even larger using tile that measured 6″ x 17″.

2nd shower tile going in

We kept the glass accent tile to a minimum, utilizing it inside each niche and next to the shower head and valve.

2nd shower niche going in
Blue glass going inside the niche.

Using a frameless fixed panel of glass without a door keeps each shower more open and easier to access. It also means one less thing to have to clean, maintain, or eventually replace.

By covering the curb with a towel before turning on the water, very little water escapes to splash on the nearby baseboard or drywall. A small price to pay, we feel, in order to keep the shower area more open.

In terms of size, the second bathroom shower measures 3′ wide and 5 1/2′ long, while the master shower is slightly larger at 3′ x 5′ 10″. Both spaces are very comfortable to shower in.

2nd shower done

We chose to tile the ceiling of each shower since, in our experience at least, drywall doesn’t tend to hold up very well in this area, instead flaking or peeling off over time. By combining the tiled ceilings with their lower height than the room, visually we like how it makes clear that the shower area is its own dedicated space.

2nd shower niche done
The blue glass almost looks black until you step into the shower.

We liked the look of the traditional hexagon pattern, plus it feels nice underfoot, both in the showers and on the floor of the second bathroom.

2nd bath floor

Finished master bath shower with glass panel:

master shower done

In both showers we used a Speakman shower head and valve. They’re reasonably priced, and they have a good reputation for durability. We had seen them used in hotels on a couple of vacations prior to our build. We were surprised by their quality, especially for a brand we had never previously heard of before.

All of our plumbing fixtures, including these shower heads, are Water Sense certified in order to keep our total water usage to a minimum, while also hopefully reducing our annual water bill.

Although I’ve read complaints from users online about their dissatisfaction with a lower flow shower head — some even going so far as to remove the flow restrictor inside the head in order to increase the flow of water — we couldn’t be happier with our shower heads, faucets, and toilets. So far, at least, we’ve had zero issues with any of these Water Sense certified fixtures.

Master bath niche with red glass accent:

master bath niche
The seat is nice to have, not for sitting though, mainly for holding shampoo and soap, and a nice spot to put a towel for drying off.

Master bathroom floor in the weathered black tile:

master bath floor

A second view of the black tile as it meets up with the hickory flooring in the master bedroom:

2nd master bath tile

The tile in the entry area as it meets up with the hickory wood flooring:

entry tile

The hickory meeting up with the kitchen tile:

kitchen family rm corner finished

With all of our flooring complete on the main floor, the only area left to finish up was our basement floor. I’ll discuss the decorative finish we came up with for the concrete slab in the next blog post.

Flooring: 3/4″ Hardwood

4

Hardwood vs. Carpet

In our previous home we made the decision not to use any carpet. Not only did we prefer the look of combining tile (for wet areas) with hardwood (living areas and bedrooms), we also knew these surfaces would be easier to keep clean than carpeting. Although I grew up in two homes that both had mostly wall-to-wall carpeting, it was only after having to rip up several rooms of carpet that I realized just how much dirt and general detritus gets trapped below the surface.

There does seem to be an element of generational change (some would argue even social class) involved in this choice between carpet and hardwood. For example, my parents, who grew up on farms in the 1940’s without carpet, were shocked that we preferred hardwood flooring since having wall-to-wall carpeting was a big deal for them when they moved to Chicago in the late 1950’s. To them, hardwood flooring signified the outdated past while carpeting was the future.

Having lived with both, I don’t think I’d ever choose to go back to carpet. In addition to being much more visually interesting, I find hardwood flooring not just easier to keep clean but much easier to fix or repair should damage occur.

Which species of wood?

For our last house we went with pre-finished 3/4″ x 5 1/4″ wide plank Australian Cypress. Even though we loved the look of the Australian Cypress, it was more expensive than other species and it seemed to dent more easily than its Janka hardness score would suggest.

Oak is, by far, the most popular wood species for flooring, seen in countless stain color variations, but we wanted to try something with more natural color variation from one board to another.

For our new home we knew we still wanted to go with only hardwood and tile, even though there are now more eco-friendly and sustainable carpet options. We also knew we’d have to utilize a low or no VOC finish for the wood flooring in order to maintain a high level of indoor air quality.

Another option to consider is engineered vs. 3/4″ solid hardwood flooring. Because of the additional wear layer, and because I’d previously worked with a solid hardwood in my last house, we opted for the 3/4″ solid.

Also, since we went with a prefinished hardwood last time, this time we decided to try a traditional install, meaning sanded and finished in place.

The only real gripe we had with the pre-finished flooring in our last house was the beveled edge between boards, creating grooves that can trap dirt. Also, we felt it was slightly less visually appealing than a traditionally finished floor. Nevertheless, we would consider pre-finished flooring to be a viable option, especially if you’re having to work under severe time constraints and you need a room or whole house completed quickly.

3/4″ x 4″ Hickory

After considering various wood species, we settled on Hickory since it can look similar to the Australian Cypress, while its Janka hardness score is slightly higher, giving us some added durability. It’s also harvested and shipped from within the US, so it cuts down on shipping costs and total embodied carbon emissions.

Looking around locally, including our local Floor & Decor, I could only find manufacturers who packaged their flooring in boxes of shorter boards (the longest boards typically in the 4′-7′ range). Using shorter boards tends to produce a choppy look, reminiscent of a brick running bond pattern.

Online the options seemed much better, although shipping costs had to be factored in. It was also difficult to find the color variation we were after since much of the Hickory that’s available would be classified as clear or select (NWFA). In the end, we used Countryplank, ordering their Old Growth Hickory in random lengths (2′-10′).

After initially receiving someone else’s order in an entirely different species, Mark from Countryplank quickly took care of the problem and got my correct flooring to me the following week. Once it showed up on site, the boys were back to help me carry it in the house — as always, many thanks to them for helping us out with the grunt work.

unloading wood flooring
Smitty and Ricky helping us unload the truck.

Of course when the flooring was being delivered it turned out to be one of the coldest days of the year with plenty of snow around. Thankfully, with the guys helping us, it went pretty quick.

Installation

Before installing the Australian Cypress in my last house, I used a book from Don Bollinger as a helpful how-to guide. The book came with a video companion, which I’ve since lost, but much of the footage has shown up on YouTube:

And there are many other helpful videos available as well:

After clearing a room of tools and other construction related items, I set to work prepping the Advantech subfloor.

family rm b4 wood floor
Setting up to prep the family room subfloor.

Although the Advantech is said to resist moisture better than other OSB or plywood subflooring, because of the delay in construction after firing our pair of GC’s, the sheets of Advantech saw more exposure from the weather than is ideal.

Nevertheless, apart from having to grind and sand down some edges that had expanded due to moisture, the Advantech held up incredibly well. In addition, since the framers used nails to fasten it to the floor joists I went through each room adding decking screws to help stiffen the floor even more.

Once this was done, I was able to put down some red rosin paper. In my last house I had used 15# roofing felt, but since it’s embedded with asphalt I decided, for the sake of indoor air quality, that the red rosin paper was the better option. Rather than using it to control moisture, it’s mainly helpful in keeping a neater workspace as the flooring goes down.

mbr red rosin
Red rosin paper going down in the master bedroom.

With all of the red rosin paper down, it was time to bring in the tools and to start arranging piles of wood flooring based on length and color. As I unwrapped each pile of boards I went looking for the longest and darkest boards, making sure to have them nearby as I tried to use the longest boards first, and then be selective about how to place the darkest and most attractive pieces. When all the rooms were complete, I wanted the leftovers to be mostly shorter and lighter colored pieces.

family rm prepped 4 wood
Family room prepped for hardwood flooring.

The only other major decision before beginning to install the flooring was orientation. Most homes utilize the longest wall in a space as a guide, installing the wood parallel to this wall. Ideally this would also mean the flooring runs straight from the front door entry area to the back of the house in bowling alley fashion. This assumes the floor joists are perpendicular to the direction of the wood flooring. In our last home, and in our current Passive House, we could have oriented the hardwood flooring in this ‘straight’ pattern, but after trying and loving a diagonal pattern in our last home we knew we wanted to stick with this angled pattern. The only significant downside to the diagonal pattern is additional cuts are necessary so, therefore, more wood is required.

family rm wood going down
Arranging pieces before getting started.

The use of spline pieces, or split tongue, was helpful when making a change of direction, or establishing the border where the hardwood flooring met the tile in the kitchen, utility room, entry, and bathrooms.

kitchen outside corner w: router
Finishing up the family room. Note the shorter pieces of spline on the tile, and the router used to make a connection between the main pieces and the wood border next to the kitchen tile.

When I needed to create a groove I used a groove bit with the Bosch router before gluing and installing a section of spline. This was especially helpful where the wood met up with tile and I needed to first create a border piece.

First, using a table saw I would cut off the tongue side of the board, facing this side towards the tile. Now with the groove side exposed I could cut to length the piece I needed to butt up against this border piece against the tile. Once it was cut to length I could use the router to make a groove on the end that would be in contact with the border. With the border piece and the field piece now having grooves it was easy to add the spline in between, making for a tight, durable connection between these two pieces with some wood glue.

family rm mostly done
Done with the family room and ready to head towards the front door.

The diagonal pattern also means that the flooring nailer runs out of room before you get to the wall because of the angle involved. For these last few inches I utilized a trim nail gun, shooting into the tongue and face nailing a couple of nails at the outside edge. Even though these nails are significantly weaker than the flooring nails, we haven’t experienced any gapping or other issues at the perimeter of our walls. This may be due to the fact that we don’t see wide swings in the levels of indoor humidity (typically the house stays within 30-55% relative humidity; most of the year hovering around 40%) because of the air tightness and high levels of insulation required of a Passive House.

It probably also explains the lack of floor squeaks. When there are wide swings in outdoor humidity we sometimes get a couple of ‘pops’ from the wood flooring itself, but we’ve never had an issue with the floor joists/Advantech connection squeaking. In our last home, a conventionally built tract home, similar changes in humidity made our wood floors sound like they were in a hundred year old farmhouse, popping with almost every step until the humidity and the wood itself had a chance to stabilize.

One of the best tool purchases for the entire build was this Powernail ‘persuader’. Whether at walls, or out in the field, this tool works exceptionally well at closing unsightly gaps that would otherwise need to be filled with wood filler.

powernail persuader
The Powernail ensured a much tighter floor installation.

And the Powernail was an excellent guide for identifying bad boards — if it couldn’t close gaps on a particular board, it meant that board shouldn’t be used.

For spots or areas that would need some extra attention during sanding, I marked these with a pencil, either with an X or a circle.

marks for xtra sanding
Spots requiring careful sanding marked with X’s or circles.

Before sanding I also went around applying wood filler to all of the nail holes, any voids in the many knots, and to any remaining gaps between boards (mostly where the ends butt together). For the deepest voids in the knots I made two passes with the wood filler, sanding in between coats. In the end this produced a much smoother finish.

I found the Timbermate brand online, and was pleasantly surprised at how easy it was to work with and how well it’s performed over time. I started out with half a dozen different colors, but eventually narrowed this down to just two colors: Beech/Pine and Chestnut. In effect, these two colors spanned the wide variation in color from light to darker boards.

Although it claims to be zero VOC, it does have a distinct and slightly funky smell as it comes out of the jar. This odor completely disappeared once it was sanded down and the floors were sealed with tung oil. The Timbermate is also very easy to sand smooth.

wood putty for floors

Sanding the Floors

Thankfully, the flooring didn’t require a lot of sanding, nowhere near the amount typical in strip oak flooring. Overall, the flooring did seem to be precision milled and I ended up with very few completely unusable boards.

not much sanding
This was about as bad as it got. Most boards came together much better than this.

I could’ve rented a traditional floor sander and edger, but after reading about Festool’s orbital sander and then a similar sander from Bosch, I decided to try the Bosch out and see what it could do. I started in a smaller room, my daughter’s bedroom, just to see how long it would take to do a room-sized amount of sanding. Starting with 40 grit for the worst areas, I slowly worked my way through increasing grits, ending at 150 for a smooth finish ready for tung oil.

Since I was able to work through the various grits in just over an hour, I decided to keep using the Bosch sander for the duration of our project. Again, if I was sanding conventional oak strip flooring purchased from a big box store, I definitely would’ve rented the normal sander/edger combo.

bosch sander
Bosch orbital sander.

Since I was installing and finishing room by room (we had a lot of construction ‘stuff’ to maneuver around, but that we wanted to keep onsite), renting the equipment, in addition to being more expensive, would’ve meant a lot of back and forth between home and the tool rental center. Also, once the flooring was done, I still owned an excellent sander. It’s easily the best sander — palm or orbital — I’ve ever owned. The lack of vibration compared to comparable sanders makes working with the Bosch a real pleasure.

bosch sander ready to go
Utility room ready to be sanded.

Hooked up to a shop vac with a HEPA filter, the sanding dust was kept to a bare minimum, making the house pleasant to work in, regardless of the amount of sanding just completed.

Just before starting the wood floors my Fein shop vacuum died on me. I picked up a Ridgid brand vacuum from Home Depot mainly because it was the quickest option, fully expecting to be disappointed by its performance. To my surprise, it worked even better than the Fein vacuum and at a much lower price point.

rigid vacuum
I was surprised how well this Ridgid vacuum effectively contained the sanding dust.

Once the floors had been sanded down, it was finally time to start finishing with tung oil.

wood entry tile
Front entry transitioning to hardwood flooring.

Finishing the Floors with Tung Oil

Before we started the tung oil we made sure to tape edges where the wood met tile, mainly to keep clean-up to a minimum, but to also protect the grout from being darkened by the tung oil.

wood tile tape b4 tung
Utility room ready for tung oil.

Real Milk Paint, the company I purchased the tung oil from, has an excellent how-to video on doing wood floors:

We used close to a 50/50 mix of tung oil and citrus solvent, with just slightly more citrus solvent added to encourage deeper penetration of the tung oil.

My ‘helpers’ enjoyed doing the first coat with me in each room since there was such a dramatic color change as the tung oil initially went down. The tung oil really makes the grain and all the color variation in the wood really come to life.

First, we brushed in from the perimeter edges several inches, before rolling the rest of the floor with a lambswool roller connected to a paint stick. We were careful to not get too far ahead of the roller with the cutting in, hoping to avoid any ‘flashing’ that could show up where these areas meet up once the floor was completely dry.

family rm 1st coat
Anita brushing in the edges before rolling out the remainder of the floor.

It was always exciting to watch this dramatic transition from light and dusty to amber, dark, and stunning.

starting in br closet tung
Beast helping me start in her bedroom closet.
tung oiling s's br
Making our way across her bedroom floor.

Close-up of the hickory as the tung oil is applied:

dry tung
Dramatic change in color as the tung oil is applied.

Making progress across the family room floor:

dry tung family rm
First coat of tung oil going down in the family room.

Once the floor had a full coat of tung oil applied, we waited about 45 minutes before looking for areas where the oil had completely soaked in — this was especially pronounced around the many knots in the wood.

kitchen wet stay wet
Family room coated with tung oil.

After waiting an additional 45 minutes, we hit these ‘dry’ spots again. Once another 45 minutes were up we then wiped down the floors with cotton rags, available in 20 pound boxes from a local paint store.

s's br just tung oiled
Floor rolled, waiting for the tung oil to soak in.

Typically the floors were completely dry within 24 hours, but sometimes we waited one more day before repeating the same process a second and final time.

br entry after tung
Following morning after first application of tung oil.

After two separate days of applying the tung oil in this way, the floor was finally finished and I was ready to move on to the next room.

s's br after tung
2nd bedroom ready for baseboard.

It does take quite a few rags to wipe the floors down properly. It’s also worth noting that we were extremely careful once we were done to dispose of the rags responsibly in order to avoid a fire from the oil-soaked rags — a more common occurrence than most people realize.

final wipe down in mbr
Anita doing a final wipe down in the master bedroom.

In fact, when we thought we were done wiping, we’d go back one last time, walking the floor with rags under our shoes to get the last bit of tung oil that was inevitably still oozing up out of the hickory.

kitchen family rm after 1st ct tung
Family room ready for second day of tung oil application.

Here’s a close-up after the first coat color change next to the kitchen tile. We really like the contrast between the warmth of the wood and the cool gray of the tile:

kitchen wood connection after tung
Family room meets kitchen tile.

We also used this tung oil process on our basement stairs, which had hickory treads, along with a landing covered in hickory installed diagonally like the rest of the flooring.

Paul, from Signature Stairs, was the salesperson for our basement stairs. He made measuring and ordering what we wanted very easy, and he even took the time to stop by right after the stairs were installed and immediately took care of a minor touch-up for us. We’ve been extremely happy with the stairs. In fact, they were so well built we’ve yet to have even a single squeak, which, when compared to our last home, is extremely impressive.

base stair steps after tung

Because of the amount of variation in the wood, it was a lot of fun playing around with how best to show off the darker pieces. I always tried to keep in mind where furniture would end up, saving the most dramatic pieces for those areas that would remain out in the open and highly visible.

mbr b4 tung
Master bedroom ready to be sanded.

And it was always exciting to see the transformation from unfinished to very rich looking as the colors in the wood popped after the application of the tung oil.

mbr after tung
Master bedroom after tung oil.

We really love the color variation from one board to another. The range of colors and textures in the grain is stunningly beautiful. Visually the floors run the gamut from what looks like pine, walnut, tropical hardwood, oak, maple, birdseye maple, some boards with insect damage and staining, to of course clear hickory. This wide variety of colors and textures celebrates the full breadth of what the wood has to offer (as opposed to just clear grade), and it nicely adds to our overall Urban Rustic and wabi sabi design aesthetic for the house.

Here are some close-ups of individual boards showing this wide variation in looks:

tropical
Some of the darker boards look like walnut.
orange w: insect
A few boards had this insect or worm hole damage, including some attractive streaking.
lighter almost pine
Waves reminiscent of end grain Douglas fir.
light w: staining
There were several boards with this dark streaking over a much lighter background, as if the wood had been exposed to fire.
brown light red
The darker colors ranged from this walnut brown (at left) to a much redder, almost exotic tropical hardwood color (on the right).
lightest
The darker pieces were nicely balanced by many other lighter, more natural toned boards.
close-up knot w: staining
Even the knots themselves can be quite dramatic in terms of colors and smoky looking swirls.
beetle pine
There were even a couple of boards that look very much like beetle kill pine.

The orientation of the flooring was installed going with the main direction of foot traffic so that it feels like you’re almost always moving with the pattern in the floor rather than against it. In order to maintain this feeling throughout the house, it required changing direction in a couple of areas, for instance, where the kitchen and family room transition to the bedrooms. In these areas I used a transition piece in the door jamb of each bedroom to mark the change in direction.

mbr cu floor color variation
Master bedroom complete. Ready to change direction into the family room.

When the flooring changes direction it makes for a dramatic visual accent as the contrasting angles meet up. Below is the same area shown above, now with the family room flooring installed (but unfinished) next to the tung oiled master bedroom flooring:

family rm mbr wd flr meet
Change in direction from the family room (on the left) to the master bedroom (on the right).

Living with Oil-finished Hardwood Flooring

The tung oil finish is definitely softer and more prone to damage when it is first put down than a floor covered in a clear coat would be. After move in day I definitely noticed some scuff marks but no major damage. Since then, the tung oil finish has been holding up well.

Granted, we take our shoes off when entering the house, which definitely helps to keep dust and dirt under control, particularly the grit that can scratch wood floors. It also helps that we keep all food and drink in the kitchen. But this would’ve also held true had we gone with a clear coat finish on the wood, so there was no change in our behavior required from our last house to this one.

There’s only been a couple of times that a significant scratch or dent required getting out the Timbermate wood filler, the orbital sander, and the tung oil. In these cases, it was much easier to repair these relatively small spots than it otherwise would’ve been had the same damage occurred under a clear coat.

Overall, the main advantage a natural oil finish has over any clear coat is the amount of texture in the wood grain that’s allowed to come through (especially when viewed on an angle), combined with a matte finish, so the wood tends to look much more natural and warmer looking than it would if covered by multiple coats of clear finish.

mbr bath wood transition
Transition between master bath and master bedroom.

Nevertheless, I don’t think I would use an oil finish if we had a large dog, or if we preferred to keep our shoes on all the time. Under those circumstances, I’m guessing you’d have to commit to an annual spot sanding and tung oil application, at least in high traffic areas, to keep up with the damage so that it didn’t become too unsightly.

Whether using a natural oil finish, or a more common clear coat, it’s worth exploring the options, including coming up with a few sample boards just to make sure you’ll be happy with the final look. A website like Green Building Supply is especially helpful in this regard, as they offer several brands of each kind of finish in low or no VOC products.

finished floor variation

It’s also worth noting that the initial wide contrast between the lightest and darkest boards has mellowed over time, so although the contrast is still evident it’s not quite as dramatic as it once was when the tung oil was first applied. Even so, we’re extremely happy with how our wood floors have turned out, and we have no regrets in terms of our choice of wood species or the use of an oil finish.

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

0

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

10

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 )

2

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

Dressing up the Basement: Steel Beam and Concrete Walls

2

With the Zehnder and the Mitsubishi systems installed, I had some time to kill waiting for the siding guys to start, and for my first blower door test to take place, so I moved on to painting my structural steel beam and the exposed concrete walls in the basement. Apart from a couple of walls for my wife’s office that would eventually be drywalled and painted, and a decorative finish for the concrete floor, these were going to be some of the limited finished surfaces in the basement.

We’re glad we decided to leave the basement ceiling unfinished. In doing so, not only did it mean a more straightforward installation process for mechanicals, it also means if any issues develop in the future we’ll have easy access to identify and solve any problems.

I debated whether or not to spray the basement ceiling — the floor joists and the underside of the sub flooring — but decided that the color change (some shade of gray? black?) wasn’t worth the effort.

Although obviously not to everyone’s taste, we like the unfinished look of the ceiling, especially when combined with the texture of the painted concrete walls and our painted steel beam (not to mention the eventual decorative finish for our concrete floor slab — I’ll go through the details in a future blog post since it was applied much later in the build).

For the beam, I first used a wire brush and some sandpaper to remove any loose and flaking rust. Using a Sherwin Williams primer, their All-Surface Primer tinted gray, I applied a heavy, uniform coat to help prevent the return of any rust in the future (keeping humidity in the basement under control should help a lot in this regard).

beam w: primer and rusty red
After wire brushing off loose rust, priming the beam in preparation for paint.

After priming, I then applied two coats of a Safecoat product, their semi-gloss in Patriot Blue.

Safecoat semi-gloss Patriot Blue for steel beam
Patriot Blue for the steel beam.

If I could do it over, I think I’d use Safecoat primers and paints for almost all of the interior surfaces. For the sake of convenience, since they have stores near me, I mainly used Benjamin Moore’s Aura Matte and Satin for walls and trim, and ended up mostly disappointed with their performance — hiding is pretty mediocre, flashing when you try to do spot touch-ups, and over-priced for the level of quality. Benjamin Moore does a great job with their marketing materials and with the look of their labels, I just wish the same level of thought and attention to detail went into the quality of their finishes.

Safecoat is available at various stores in the US, but unless you want a stock white, tinting may happen at Safecoat headquarters before shipping to individual stores, so there can be a wait involved (check with your local supplier for details).

I had good luck ordering from Green Building Supply in Iowa. After ordering online, the products are shipped directly to the job site or your home. This gives you access to high quality No or Low VOC products that, at least in my case, are otherwise currently unavailable in local hardware or paint stores.

Unfortunately, they can’t ship during cold spells, since the paint could freeze and be ruined. When it was cold and I needed product, I found Premier Paint and Wallpaper just outside of downtown Madison, Wisconsin (about a 2 hour drive for us). They’re a family-owned shop, and it shows. They have a nice selection of Safe Coat products. In fact, their wide range of products from various brands is impressive, and the people who work there are really helpful and just easy to work with. Unfortunately, I haven’t found a similar paint store in my area. Around me, Benjamin Moore (aka JC Licht), Sherwin Williams, and Pittsburgh Paint stores dominate the market. The smaller mom-and-pop stores, for the most part, don’t really exist anymore, which is a shame.

beam w: primer and paint
Paint going over the primer.

The Safecoat products that I’ve used typically have some odor, but what little smell they do have tends to dissipate rather quickly (this is particularly noticeable if you change back to a more conventional coating with more VOCs that may take weeks before its distinct odor finally disappears).

painted beam w: zehnder and hpump
Finished beam.

It’s a shame that so many structural beams end up covered over, normally considered too humble, i.e. ugly, to be left alone. In keeping with our Urban Rustic design aesthetic, we think that if they’re given even just a little bit of attention and care they can prove to be a real visual asset to a space, especially in a basement if a more relaxed, informal look and feel is acceptable or even ideal.

cu paintd beam in basement
Close-up of the painted I-beam.

Leaving the spine of the house exposed like this with a bold color emphasizes the job it’s actually doing, and it honors the material by making it front and center visually in the space, rather than trying to hide it away behind drywall or wood. This seems only appropriate since beams like this help keep a house standing upright.

basement walls primed
Another view of the beam, and the recently primed concrete walls.

Once the beam was completed, I moved on to priming the exposed concrete walls.

beast helping me prime basement
Getting some help priming the concrete walls. She lasted about 15 minutes, at which point it clearly turned into work.

Paint color can be a finicky thing. After priming the concrete walls, I used a Benjamin Moore color, Jute, as the finish coat. In the basement it looks great, exactly what we were looking for: a nice, warm neutral khaki color. Upstairs, however, when I later did a test swatch on the new drywall this same color looked horrible, taking on pinkish flesh tones, so we ended up having to use a different color for most of the first floor. Testing out colors, even in relatively small areas, can save a lot of time, money, and headaches later on.

painted basement walls
Concrete walls after paint.

It was really important to me that the basement foundation walls be left exposed, with no insulation or drywall.

20190831_120510

I wanted all of the texture, imperfections, and overall character of the exposed concrete to be vividly on display.

20190831_120625
There are a couple of areas of ‘honeycombing’ around one basement window. Under the right lighting, it creates a nice visual effect.
20190831_120205
Areas with exposed conduit were also painted.
20190831_120703
20190831_115629

With a good chunk of the basement complete, it was time to move outside and get some work done before the siding began, and before we had our first blower door test performed…

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.