kimchi & kraut

Passive House + Zero Net Energy + Permaculture Yard

Category Archives: Net Zero

Basement Slab (Air Sealing #5)

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The Bottom of our Thermal Envelope

Following Passive House principles, we knew we were going to insulate and air seal our basement slab. As explained on the Passipedia website:

“The most important principle for energy efficient construction is a continuous insulating envelope all around the building… which minimises heat losses like a warm coat. In addition to the insulating envelope, there should also be an airtight layer… as most insulation materials are not airtight. Independently of the construction, materials or building technology, one rule is always applicable: both insulation and airtight layers need to be continuous.”

 

airtightness_with_logo

Illustration courtesy of: passipedia.org

The illustration above also shows the “red pen test”, which is supposed to occur in the design phase of a project, when it’s much easier to address weaknesses or errors in the details of a design — not necessarily just for air sealing, it’s also effective when looking for points of potential water intrusion (e.g., this GBA article), or even to test the thermal layer for areas of thermal bridging. The basic idea is that if your layers aren’t continuous you’ll find yourself lifting your red pen, meaning it’s an area that needs to be addressed.

An effective way of thinking about a structure, utilized by high-performance builders, is to think in terms of 6 sides rather than just 4 when contemplating the details for air sealing and insulating: 4 walls, the attic/roof, and the basement (or frost-protected slab).

A similar approach to Passive House for building high-performance structures is adopted by advocates of The Pretty Good House concept, even if it’s less stringent, more open to interpretation, and tends to be more “rule of thumb” rather than energy model driven (e.g. PHPP or WUFI).

Based on our climate region, which is Zone 5, we decided we wanted to shoot for 16/20/40/60 for insulation R-values — the series of numbers represent R-values for under the basement slab/ the exterior foundation walls/ framed exterior walls/ and the attic (our attic R-value proved to be significantly higher than 60, but more on that later) — which is in the ballpark for both PGH and Passive House (here’s an excellent overall summary of the PH concept I recently came across: EcoCor).

Arguably, the “sweet spot” for how much insulation makes sense for these areas, even when adjusted for climate region, is still a topic for heated debate. Nevertheless, it’s important to keep in mind that the more simple the form your structure takes — for example, 2-story cubes without basements —

the easier it is to achieve Passive House, or similar building standards, since it simplifies framing, air sealing, and limits the exterior surface area in ways that a single story ranch that is spread out and has all kinds of nooks and crannies does not (the difference also has serious ramifications for overall heating and cooling demand). Likewise, simple forms also make it easier to figure out how much insulation you need to reach a benchmark like Passive House or PGH. A simple form can also have durability implications.

Our R-values were based on a number of considerations: the construction drawings of our original builder, information made available by Hammer and Hand (in particular their Madrona House project), and articles on the Building Science Corporation (in particular: 1 and 2) and Green Building Advisor websites. These resources, all of which have proven to be indispensable at every stage of the build, have made our project possible.

In terms of the details around the slab and the foundation walls, this article from the DOE also proved to be especially helpful: Foundation Handbook

2-04_no-cap

Illustration courtesy of: foundation handbook.ornl.gov

After considering various insulation choices (Wall Assembly), we decided to go with Roxul for under our slab, the exterior of our foundation, and our wall assembly (blown-in cellulose in the attic was the only significant deviation from the use of Roxul).

Here’s how the basement slab portion of our project progressed:

 

 

Roxul Comfortboard 80 (2″ + 2″)

To get to an R-value of 16 we used two layers of 2″ thick Roxul Comfortboard 80 (R-4 per inch).

We installed each layer with staggered seams, although the Roxul representative I spoke with via email insisted that because the Roxul is so dimensionally stable this isn’t nearly as important as it would be with rigid foam insulation (the same holds true with a double layer of Comfortboard 80 on the exterior side of wall sheathing).

roxul long view two layers

The second layer of Roxul being installed.

 

roxul before stego

Installing the Roxul around the rough-in bathroom pipes, sump, and ejector pits.

One of the many benefits of using Roxul is that the material wants to stick to itself, whether in batt or rigid board form. This makes for tighter joints between pieces, and even when cuts around obstructions are less than perfect it’s easy to fill in any gaps with torn apart pieces of Roxul (again, this holds true for both Comfortboard 80 and their version of batt insulation).

roxul stuffed in around basement pole

Stuffing bits of Roxul around the base of one of the steel columns.

Close up of the Roxul installed around the roughed-in bath PVC pipes.

roxul around rough-in bath

Another view of the 2-layers, mostly installed.

roxul before stego - facing ladder

A Roxul rep told me to take into account a loss of R-1 due to the compressive pressure of the poured concrete, thus our R-16 for two layers of Roxul is, according to Roxul, really an R-15. Having installed the two layers myself, walked on it during and after installing the vapor barrier (see below), my guess is in some areas this loss in R-value is even greater than R-1.

Based on the comments quoted in a GBA article (Sub-Slab Mineral Wool), I would have to say my experience was exactly the same: in some areas the Roxul seemed to lose most, if not all, of its rigidity. I’ve also noticed while working with both the Comfortboard 80 and their batts, that there seems to be a variation in the material from piece to piece and bag to bag. Some pieces are very easy to cut (these pieces are noticeably stiffer), while other pieces seem “mushier” or lacking in rigidity — either under or over-cooked perhaps — making them more difficult to cut and work with. This seems like less of an issue for vertical applications (i.e. walls), while potentially troublesome for horizontal applications under a slab — especially if you’re depending on that R-4 per inch to meet the demands of energy modeling for a certification program like Passive House.

I’m glad we’ve been able to mostly avoid foam insulation in the build, but seeing the Roxul in a real world application does make me wonder if some kind of rigid foam might’ve given me a more consistent whole floor R-value.

 

 

Stego Wrap

Once the two layers of Roxul were down, it was time to install the vapor barrier over the insulation. While the Roxul acts like a blanket, helping to maintain a consistent temperature in the basement, the vapor barrier helps to keep moisture and soil gases (mainly Radon as I understand it), at bay.

The product I’ve seen used in most Passive House, Pretty Good House, or equivalent projects, is Stego Wrap. Here are two videos detailing its installation and its benefits:

 

Another product I came across while researching options was Perminator.

Here’s a video detailing the use of the product:

In my area — the suburbs of Chicago — the closest supplier of Stego Wrap was HD Supply.

starting stego around roug-in pipes

Starting around the rough-in bathroom pipes.

We used the 10 mil version of the Stego Wrap. The material is very durable and fairly hard to damage. Even when tears occurred, it was easy to patch with pieces of the Stego red tape, or a combination of a cut piece of Stego Wrap with pieces of the red tape.

stego going down

Stego Wrap carried up the wall and taped to keep it in place.

Installing the two layers of Roxul on the basement floor was pretty straightforward, while installing the Stego Wrap was generally a pain in the ass. Maybe I was just tired, but I really didn’t enjoy installing it at all. For example, it was difficult to keep it tight to the walls, although I learned to leave it hanging fairly loose at floor-wall junctions, which definitely helped. Getting the first row straight, flat, and smooth was time consuming, and annoying, but it did make getting successive rows installed straight much easier.

jesus helping me w: first row stego

Jesus helping me install the first row of Stego Wrap.

 

sealed basement pipe close up before pour

Stego Wrap wth red Stego tape and a Roflex gasket from 475 HPBS.

The pipes after air sealing with EPDM gaskets and red Stego tape:

sealed basement pipes with overlapping Stego

Once all the Stego was in place, we added a 1/2″ of rigid foam insulation at the floor-wall junction as a thermal break. I wanted to use Roxul Comfortboard 80 (their 1.25″ thick version) even for this, but time (Comfortboard 80 is still a special order item in my area, meaning it’s always about 2 weeks away from the time you place your order — hopefully this changes in the near future) and money made the foam an easier choice.

stego w: foam close up

We kept the foam in place by running a bead of OSI sealant on the back of each section before pushing it up against the Stego Wrap. For the most part this seemed to work well.

stego w: foam at slab edge

Roxul, Stego Wrap, and Foam installed.

Here’s a close-up of everything installed in a corner:

stego w: foam at a corner

One of the real disappointments of installing the basement slab was seeing the concrete guys put down the welded wire mesh (typically noted as W.W.M. on construction drawings) — basically chicken wire with pointy ends (I exaggerate, but not by much).

If I could do it over again, I would look into using a concrete mix containing sufficient pieces of fiberglass, or some other alternative, so that using the welded wire mesh could be avoided altogether.

 

I was already familiar with the idea of fiberglass used in place of metal in concrete forms, having experimented with decorative concrete last year and having seen videos like these:

 

I’m not sure why I didn’t think to ask for fiber reinforced concrete instead of the normal welded wire mesh — it was one detail that just got missed, unfortunately.

As the wire mesh went down, the guys could see how annoyed and concerned I was by the holes it was making in the Stego Wrap that one of them, Oscar, started helping me bend the pointy ends up. Once they were safely pointed up, I went around with the red tape to patch the many tiny holes in the Stego Wrap. Not a fun way to kill a couple of hours.

Why my architect or the concrete guys didn’t suggest a mix with fiberglass instead of the welded wire mesh is unclear. The reality with any green build, especially if you’re acting as GC, is you’re likely to be the only one who really cares about getting the many details right, especially if the architect and subcontractors have never built like this before — they were just doing what they always do.

A couple shots of the basement floor with the welded wire mesh in place:

A closer view with all the elements in place prior to the pour:

corner of basement pre-pour

 

 

Concrete

Here’s various shots of the slab itself being poured:

hole in floor for basement slab

It was necessary to cut a hole in the subfloor just inside the front door in order to get the concrete into the basement.

 

concrete going thru floor

 

long view of brace for pour

The guys starting at the back of the basement.

 

leveling back corner of basement

 

back corner of basement pour #2

One corner complete.

 

pour heading towards basement stairwell

 

leveling towards stairwell

 

pour at stairwell

 

Tools at stairwell

 

finishing concrete at stairwell

 

troweling at stairwell

Enrique completing the trowel finish.

 

cement truck kissing corner of garage

Side of the garage kissed by the cement truck.

 

close sewer clean out

Close.

 

close long view sewer

Really close.

 

 

Slab Edge

Once the slab was in place, I wasn’t quite sure how to deal with the edge along the perimeter. As usual when I get stuck on some detail, I asked a question on GBA:

How do I seal…

Stego Wrap and Foam cut away from slab edge

Cutting away the excess Stego Wrap and purple foam.

 

close up of slab edge

Close up of the wall-slab junction after cutting everything down flush with the floor.

Using the Prosoco Air Dam seemed like the best, and most straightforward, option. In addition, after considering various ways to cover this gap after the Air Dam was down between the wall and floor, and after priming and painting the basement walls, I realized the gap visually disappears for the most part, and really wasn’t worth thinking about.

wall-slab connection after air dam.jpg

Junction between wall and slab after using Air Dam and priming and painting the wall.

 

close up of wall - slab conection after air dam

Close up of Air Dam, after primer and paint, at the wall-slab connection.

By not putting anything down to cover this gap, if the basement ever does experience water damage, it’s one less thing to remove and replace.

Solar on the Roof

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After deciding to pursue a combination of Passive House and The Pretty Good House concepts, which entail careful planning and attention to air sealing, along with a significant amount of insulation, we knew we could have a shot at Net Zero, or Zero Net Energy (ZNE) — meaning we could potentially produce as much energy as we use by utilizing solar panels on the roof.

To find an installer in our area, we utilized the website Energy Sage. In addition to useful articles and information about solar, they also work with installers who can provide consumers with competitive bids. It didn’t happen overnight, but in about a week or two, we ended up with 3-4 bids before deciding to go with Rethink Electric in Geneva, Illinois.

laying out the solar panels pre-install

The guys from Rethink staging the panels on the garage roof.

 

 

The System

Based on the suggestions from Energy Sage and Rethink, we ended up going with the following system:

  • 2.915 kW DC System
  • 4,059 kWh of system production
  • 11 Canadian Solar panels
  • 265W Module Enphase M250 (Microinverter)
  • Also includes web-based monitoring of the system’s production

In theory, this system could produce more energy than we use (it’s just my wife, my daughter, and myself who will be living in the house), particularly if we stick to all LED lighting, use Energy Star rated appliances, the heat pump water heater works as advertised, and we’re careful about avoiding using electricity when it’s unnecessary (e.g. turning off lights after leaving a room, or trying to address phantom loads).

Anthony putting self-adhering gasket over solar conduit penetration

Anthony, from Rethink, air sealing the penetration through the Intello, our ceiling air barrier,  with a Tescon Vana – Roflex gasket before sending his 3/4″ conduit into the attic.

Based on other projects I’ve read about, even homes initially built to the ZNE standard sometimes fail, in terms of overall performance, based on actual occupant behavior, so only time will really tell what impact our solar array will have on our utility bills. It looks like worst case scenario would be needing to add 4-6 more panels to get to ZNE or even carbon positive.

conduit for solar in the attic before gasket

Anthony’s conduit entering the attic, sealed with a gasket from below.

Installation by Rethink went really well, and they were happy to work with me on properly air sealing the conduit that runs from the basement at the main panel before going up into the attic, where it eventually terminates on the roof when connected to the panels.

conduit for solar in the attic after gasket

3/4″ conduit sealed for a second time on the attic side of the Intello.

 

solar mounting system being installed

The guys setting up the racking system for the panels.

 

Rethink guys on the roof

Anthony, Dan, and Cherif completing the install on the roof of the house.

 

close up of solar panels being installed

The low profile racking system has a very sleek look.

Marking another big leap in the progress of the build:

solar panels on roof

The view of our 11 solar panels from our neighbor’s driveway.

 

solar panels installed on the roof.jpg

Another view of the solar panels installed on the roof.

It was only after the installation that I realized what’s wrong with the following picture:

solar on:off against Zip sheathing #2

My screw up.

I was so worried about getting the air sealing details right on the interior, from the main floor to the attic, I completely forgot to let Anthony know about extending out his disconnect box 6″ to what will be our finished surface (once two layers of Roxul and two layers of 1×4 furring strips, along with cedar siding are installed). The day after they installed, I came walking around the corner of the house, saw this, and literally slapped my forehead (while spitting out a few choice expletives), as I realized my screw up.

Thankfully, Anthony was able to come back out and make the necessary adjustment:

corrected solar on:off

 

 

The Cost

Here’s the cost breakdown on our system (if trends continue, a similar system should be less expensive in the future):

$12,519.50  Initial Investment
$(-3,755.85)  Federal Tax Credit (ITC) 30%
$8,763.65  Net Cost of First Year
$(-3,816.00)  Solar Renewable Energy Credits (SREC’s)
$4,947.65  Net Cost After All Incentives

It will be interesting to follow the performance of the solar panels over the course of a calendar year or two, just to find out exactly how well they perform. I’ll come back here and post monthly utility statements, noting output of the panels and our use, to give people a better sense of actual performance — hopefully this will help others in the planning stages of their own project to decide if solar (and how much of it) is right for them.

Ceiling Details (Air Sealing #4)

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Installing Intello

We thought about using the Zip sheathing as our air barrier on the ceiling, attaching it to the bottom of the roof trusses, something I had seen on other builds, but after learning about Intello we decided to use that instead:

 

 

Floris Keverling Buisman, from 475 High Performance Buidling Supply, did our WUFI analysis for us, and he suggested the Intello would be a better fit for our project. The Intello is a smart vapor retarder, so it can expand and contract when it’s needed, and it’s obviously less physically demanding to install than the Zip sheathing.

Once the air sealing was complete around the top of our outside perimeter walls, and the insulation chutes had been installed, we were almost ready for the Intello. At the gable ends of the house, one last detail needed to be put in place, circled in red in the picture below:

2x6 on its side

2×6 on its side, circled in red.

By adding this 2×6 on its side, which is in the same plane as the bottom of the roof trusses, it makes it possible to carry the Intello over the transition from the ceiling (under the roof trusses) to the walls (top plates). This is one of those details that is hard to “see” when in the planning, more abstract, and two dimensional phase of designing a structure.

another angle of 2x6 on side

Another view of the 2×6 lying flat in the same plane as the bottom of the roof truss (far left).

Once the trusses were placed on the top of the walls and you start imagining how the Intello will be attached to the ceiling, it becomes much more obvious that something in this space at the gable ends of the house is needed in order to accomplish the transition from the ceiling to the walls.

long view w wdw to front door framing

Marking progress: Ceiling ready for the Intello.

After reading about so many other projects that utilized Intello, it was exciting to unwrap the first box.

unwrapping first box of Intello

Big day: opening the first box of Intello.

The directions are pretty straightforward, and the product is relatively easy to install, as long as you don’t have to do it alone.

Intello instructions

Reading through the instructions one last time before starting.

I didn’t get a chance to touch and feel the product before ordering (always fun to do with any new product), so here are some close-ups of the Intello to give you some sense of what it’s like:

Intello close up front side 2

Front: shiny side of the Intello — this side will be facing the living space.

I was curious about its strength and tried to tear it with various objects, including the cut ends of 2×4’s and the brackets we eventually used to help establish our service core. The material is surprisingly tear resistant, but a utility knife, or a stray sharp edge will cut through it (as our first plumber proved to me with his careless actions — a story for another post).

close up Intello back side

Back: matte side of the Intello — this side will be facing the attic.

Having never used the Intello before, I decided to start small and began by experimenting with it in a corner. Getting the corners fully covered while getting the material to sit flat before applying the blue Tescon Vana tape proved to be the most challenging part of using the Intello.

experimenting w: Intello in corner w: chutes above

Starting in a corner to get a feel for how the material will work.

Here’s two more pictures of the flat 2×6 helping to make the transition from the ceiling to the wall:

In order to attach the Intello to the bottom of the roof trusses, we used the staple gun shown below. Loading it is kind of counter-intuitive (online reviews complain about it not working out of the box, but my guess is — like me — they were trying to load it improperly), but once I figured it out, it ended up working really well, almost never jamming, and it’s very comfortable to hold because it’s so light weight. It should work with any standard air compressor. It was available on Amazon, and in Menards, a local big box store here in the Chicago suburbs.

staple gun

The staple gun we used to attach the Intello to the underside of the roof trusses.

Think you know how to load it?

side view of open staple gun

Staple gun ready for loading.

Guess again.

Instead of loading from the bottom, like all the finish nailers I’ve ever used, the staples load higher up, where the staples exit. And yes, there was quite a bit of swearing as I made the transition from “What the…” to “Ohhhh, now I get it…”.

It didn’t help that there were virtually no instructions on its use, apart from a tiny black sticker with an arrow pointing to where to load it (which, of course, I only noticed after figuring this out).

staple gun open w: staples

Loading the staple gun.

We started with these staples:

close up Arrow staples

But we ended up going with these instead:

close up heavy duty Arrow staples

They seemed to grab better (presumably the sharp ends make a difference), and they sit flatter on a more consistent basis (less time having to go back, or stop, to hammer home proud staples flat).

stapling Intello to ceiling

As we rolled out the Intello, it took some practice to get it to sit taught and flat before stapling.

The dotted lines near the edges of the Intello help you keep the rows straight as you overlap two sheets and progress from one row to the next. The lines also make it easier to maintain a straight line with the Tescon Vana tape (don’t ask me when I realized this latter detail — too embarrassing to admit).

taping Intello along dotted line

Follow the dotted line.

We checked our initial row from above in the attic:

first row of Intello from attic

View from the attic as the first row is installed.

Working our way through the interior walls, especially the bathrooms, was more time consuming and took more effort (I grew to hate those interior bathroom walls — first the Intello, then the service core details described below), but once we were out in the open, the Intello is fairly easy to install.

Intello covering ceiling, chutes in bg

First three rows of Intello as they approach the basement stairwell. Note the insulation chutes in the b.g. in the attic — they took up so much time and effort, and now they slowly disappear (just like most important aspects of infrastructure).

 

northwest corner of air sealed attic w: Intello

View of the Intello from a corner of the attic — note the 2×6, far left, lying flat, that helps the Intello transition from the ceiling to the top of the walls.

As Eduardo and Jesus rolled out sections of the Intello, I followed, pulling on the Intello a little to help make it sit tight and flat, before stapling.

Eduardo and Jesus helping me put up Intello on ceiling

Eduardo and Jesus giving me a hand installing the Intello.

There were a couple of sections, some of the first ones we installed, that I managed to wrinkle (one, in particular, became problematic during our first blower door test — and, of course, it was in a tight spot around the bathroom shower area), but overall, the installation of the Intello went pretty well. Like most things you do for the first time, we got comfortable and good at it just as we were finishing up.

Eduardo Jesus and full moon night sky in b.g.

Eduardo and Jesus helping me finish up the main areas as a full moon makes the night sky glow outside in the background. It was a long day (longer still for Eduardo since Jesus was talkin’ trash and nonsense all day — they’re football teammates — needless to say, Eduardo has the patience of a saint).

 

Intello from attic w: insulation chutes in bg

View of the Intello from the attic — offering up its 2001: A Space Odyssey glow.

After learning about a project on the 475HPBS website…

Masonry Retrofit

 

… we decided to use the Tescon Vana tape to cover the staples, as well as all the seams, in the Intello. I have no idea what actual impact covering the staples has on air tightness, but visually as you tape over the staples you can see how, if nothing else, it will help the staples resist pulling out under pressure from the eventual blown-in cellulose in the attic.

Even as the build progresses, it’s interesting how details like this pop up, making building “green” a never-ending process of learning something new — someone’s always coming up with a new product or a new way to do things better, faster, or less complicated — which makes the process itself very exciting.

OB applying tape

OB — the Palatine High School legend — the man, the myth, helps me tape over the seams and staples in the Intello. One of the many jobs he’s been kind enough to help me get done. We’d be so far behind schedule without all of his help.

 

on plank

View from above what will be the basement stairwell while installing the Intello on the ceiling.

 

installing Intello on the ceiling around the basement opening

Almost finished installing the Intello — saved the hardest part for last.

This was a nice moment, being able to look back and see the Intello completely installed. It’s almost a shame that we have to cover it with drywall.

Intello on ceiling long view

Intello installed and taped.

 

 

2×6 Service Core

A design goal for the ceiling was to keep mechanicals, like HVAC and electric, on the conditioned side of the ceiling air barrier. By doing this, we avoid having to insulate any ductwork for HVAC, or air sealing and insulating around ceiling lights. In effect, we completely isolate the attic, making its sole purpose (apart from ventilating our “cold roof” assembly) holding our blown-in cellulose insulation (this set-up makes it much easier to air seal the ceiling and get the insulation right — at least based on the projects I’ve read about). In order to do this, we created a service chase, or service core, with 2×6’s:

service chase w: first couple of 2x6's

First couple of 2×6’s going in.

In addition to serving as a space to safely pass mechanicals through, the only other job for the 2×6’s is to hold up the ceiling drywall. The roof trusses, directly above each 2×6, are still carrying the load of the roof and stabilizing the perimeter walls.

Simpson L-Bracket w: fasteners

Simpson bracket and fasteners we used to attach the 2×6’s to the underside of the trusses.

Here’s what the 2×6’s looked like with their brackets once everything was installed.

close up service chase w: bracket-screws

Service core 2×6 with bracket and Simpson SDS bolts.

OB and my wife were invaluable, as they helped me cut and install all the 2×6’s.

We installed the brackets first, before raising up each 2×6 to fit it against the brackets. Since the brackets were directly attached and under a roof truss, we were able to keep the 2×6’s fairly straight, even when the board itself was less than perfectly straight.

service chase w: just brackets

Brackets installed before the 2×6’s go up.

A feisty Robin kept trying to set up a nest on our partition wall (our windows and doors aren’t in yet). Apparently she believed we had created an elaborate bird house just for her. It took almost a week before she finally gave up — but not before starting multiple nests in multiple spots along the wall.

bird nest

Robin making one of her many attempts at a nest on our partition wall.

Along the outside walls, at the top of the wall assembly, there was a gap that we utilized for maintaining continuous insulation. This meant there will be no break in our thermal layer going from the blown-in cellulose insulation in the attic to the monolithic layer of Roxul Comfortboard 80 (2″ + 2″) that will be on the exterior side of the Zip sheathing.

trusses - Intello - Roxul

Adding Roxul at the top of our wall.

 

layer of Roxul at top of outside wall

Close up of the Roxul going in on top of the top plates.

 

Intello - Roxul - wall

Another view after the Roxul has been installed.

 

long view from west window w: service core complete

Marking further progress: Intello and 2×6’s installed.

Once the 2×6’s were up, we had to install our pieces of 1×4 in order to prevent the 24″ of blown-in cellulose that will be going into the attic from causing the Intello to sag.

The plans called for the 1×4’s to be installed right after the Intello, but before the 2×6’s, which would have been a lot easier and quicker, but, unfortunately, the GC’s we fired installed the interior walls too high, making this impossible. Having no choice but to methodically cut each 1×4 to fit between each set of 2×6’s, OB was nice enough to help me get it done.

close up of partition wall w: service core and 1x4 cross battens

Installing the 1×4’s between the 2×6’s began with some experimentation:

service core w: cross battens and L-brackets

Using L-brackets at first —  it proved too time consuming and expensive.

After experimenting with a finish nailer (too easy to miss and penetrate the Intello), we eventually settled on Deckmate screws. It was definitely a laborious process, but eventually we got into a rhythm and got it done, although we wouldn’t recommend doing it this way — way too time consuming.

ceiling w: 1x4 battens

Completing our service core.

We tried to keep the 1×4’s about 16″ apart, which should prevent any significant sagging in the blown-in cellulose from occurring (I’ll post photos once the cellulose has been put in the attic).

A lot of blood, sweat, and tears have gone into completing this house…

Here’s some proof:

screw got me

A decking screw got me.

In trying to avoid puncturing the Intello, I would hold a couple of fingers on the back side of the 2×6, feeling for any screws that would come through on a bad angle. A couple of times I drove a screw too quickly and paid the price.

looking up at Intello and service core from basement

View of the service core from the basement. Installing the 2×6’s and the 1×4’s also required walking the plank a few more times.

 

installing ceiling w: OB

OB making my life easier as I walk the plank installing the 1×4’s.

 

 

Maintaining the Intello After Installation

Unfortunately, there was a delay in getting shingles on our roof, due in large part to our first, disorganized plumber (again, more on this later). Consequently, we were in the awkward position of having our ceiling air barrier and service core all set up, but every time it rained we still had a leaking roof. In most areas, it wasn’t a big deal, but in about a dozen spots rain would collect and, if heavy enough, it would bulge the Intello as the Intello carried the weight of the captured water. To relieve, and ultimately to avoid, this pressure, I cut small slits in the Intello where the rain would consistently collect.

small hole in Intello for rain before shingles

Slit in the Intello to allow rain water to fall through, marked with a red marker for easy identification later.

Once the shingles were finally on, I went back and found all of these slits and taped over them with the Tescon Vana.

Tescon Vana covering hole in Intello

Hole in the Intello covered and air sealed with the Tescon Vana tape.

We also found a couple of weak spots in the Intello as we installed it, and even later, during the installation of the service core. These spots were marked as well, and they, too, got covered with the Tescon Vana tape just for added insurance against air leakage.

imperfection in the Intello marked for Tescon Vana

Weak spot, or imperfection, in the Intello. This got covered with Tescon Vana as well.

After having to fire our GC’s, we couldn’t have kept the project going without the help of family and friends. As awful as some aspects of the build have been, it’s been heartwarming to find people willing to help us see the project through to the end (much more on this later).

2 Cheshire Cats

Couple of Cheshire cats — clearly up to no good — helping us to keep the job site clean.

 

Insulation Baffles vs. Insulation Chutes

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Our structure was designed with a “cold roof”, or ventilated roof assembly. By having continuous ventilation in our north and south soffits, with a ridge vent on the top of our roof, outdoor air can freely enter the soffits and exit out the roof’s ridge vent. The benefits of this set-up are explained in these comprehensive articles:

BSC – Roof Design

All About Attic Venting

FHB Roof Venting

Here is the product we’re going to use in the soffits:

Cor-A-Vent

In order to make this kind of roof assembly work, insulation baffles or insulation chutes are necessary, especially if the attic is going to have any kind of significant amount of insulation, in particular blown-in insulation that could potentially move around and block off the soffit ventilation from the attic, thereby short circuiting air flow from the soffits through the roof’s ridge vent.

When it was time to install the insulation baffles, I assumed I could just go to one of the big box stores and (thankfully for a change) just buy something off the shelf. It didn’t work out that way.

At Home Depot they had Durovent (a foam based insulation baffle) and an AccuVent baffle (black plastic). Both were a disappointment.

I didn’t buy the Durovent — even just seeing it on the shelf and handling it in the store, it looked cheap and unimpressive. It was hard to imagine it holding up under the pressure of any significant amount of blown-in insulation pressing against it.

The AccuVent product Home Depot carried only worked in a straight line (no curve to wrap over the back of the Zip sheathing at the top of the wall assembly), ideal for a cathedral ceiling application. After looking around online, I found this other AccuVent product:

Seeing the video made me think it would be an easy installation, but once I had the product on the job site and tried to install one, the realization hit that they would be a pain to properly air seal, and again, I had concerns about blown-in insulation pressing up against it for years.

AccuVent out of the box

AccuVent on the job site. It’s hard not to look at these foam/plastic baffles, regardless of brand, and not think: “flimsy”.

Here’s the specific product info:

AccuVent label close up

And here are the installation instructions:

AccuVent install label

When I realized the AccuVent wasn’t right for our project, it was a moment of, “Uh-oh, now what the hell do I do?”

I assumed there must be a sturdier plastic baffle, but I never found one. Instead, I came across this article:

Site Built Baffles

As usual, old reliable — GBA — had already addressed the issue.

It was nice to have a solution, but I also knew it would be time consuming and back breaking (also neck straining) — the only thing worse than working with sheet goods is working with sheet goods above your head on a ladder. Nevertheless, I would sleep better knowing it was panels of OSB rubbing up against 2 feet of blown-in cellulose insulation rather than sheets of flimsy plastic. Long term solutions do wonders for peace of mind.

first chute installed and sealed

First insulation chute installed.

I used small, cut pieces of 2×4 (6 per OSB sheet) as a screwing base (visible in the photo below) to install each insulation chute  — screwing the blocks first to the roof trusses, then after putting the OSB into place, screwing through the OSB and into the bottom of each 2×4.

close up looking down chute before sealing

The blocks were first screwed to the trusses, before each sheet of OSB was attached to the 2×4 blocks from below.

Then, after installing each sheet of OSB, I went around the perimeter sealing all the gaps. Here’s the product I used for that:

close up Quad Max product label

The OSI sealant I used to cover the gaps.

Here’s what the chutes looked like once they were installed on the south side of the house:

insulation chutes long view

And this is what the chutes looked like when completed at the top of the Zip sheathing:

sealed top of wall w: sealed insulation chute

There weren’t always sizable gaps where the OSB chute met the top of the Zip, but when there was, this was pretty typical:

unsealed warped chute before sealing w: small piece

Same area after adding a thin piece of OSB to help cover the gap, and then sealing the area with the OSI sealant:

sealed small piece at bottom of chute

Looking down a chute before sealing with the OSI:

close up looking down chute before sealing

Gaps visible at the edges before sealing them up with the OSI.

Same view after sealing up the gaps:

close up looking down sealed chute

I showed up on a rainy morning to continue installing the chutes, and this picture shows the dramatic before and after view of without chutes and with chutes installed and sealed:

blue glow before and after chutes

On the left: no chutes and light visible through the soffit. On the right: chutes installed and  completely sealed.

Here’s a long view of the chutes:

epic long view of insulation chutes

49 installed with one to go (far left corner).

 

insulation chutes in corner

Final chute installed and sealed.

 

insulation chutes from outside

View from outside showing the ends of some of the OSB chutes peeking over the edge of the soffit.

 

close up of OSB insulation chutes from outside

Closer view of the top of the Zip sheathing meeting the OSB chute.

 

Intello from attic w: insulation chutes in bg

In the attic with the insulation chutes in the background, after the Intello was installed on the ceiling below.

Once the chutes were installed, I was finally ready to put the Intello on the ceiling, which thankfully I didn’t have to install by myself.

 

Roof Details (Air Sealing #3)

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Top of Wall and Roof Connection

Once the wall assembly details were figured out, and our ceiling set-up detailed, the transition between the two became the next challenge. In other words, how to carry the air barrier over the top of our exterior walls.

I found this helpful article by Chris Corson from The Journal of Light Construction:

An Affordable-Passive-House  (pdf)

Using a waterproof peel-and-stick membrane to wrap over the top of the wall (going from exterior sheathing — in our case 7/16″ Zip sheathing — to interior side of the top plates) seemed like the easiest way to maintain a continuous air barrier at the wall-to-roof junction. The membrane would also have a nice air sealing gasket effect after the trusses were set in place.

I also found this excellent Hammer and Hand video on YouTube (one of their many helpful videos):

Wall-to-Roof Air Barrier

Also, by being able to carry the Zip sheathing up above the top plate of the wall, hugging the bottom of the trusses, meant our 4″ of Roxul Comfortboard 80 over the Zip sheathing would rise above the top of our walls, so that thermally we would be protected going from the exterior walls to the attic, which will be filled with 24″ of blown-in cellulose — making our thermal envelope continuous for the whole house: under the basement slab – exterior of foundation – exterior walls – attic (except for one small gap at the footing-slab-foundation wall connection, which I talk about in a separate post: Foundation Details).

A high R-value wall meets up with a high R-value attic, with no thermal bridging, making our thermal layers continuous. When this is combined with an equally air-tight structure, conditioned air cannot easily escape — resulting in a significantly lower energy demand for heating and cooling (and therefore lower utility bills), and added comfort for the occupants.

Here’s a nice diagram from Fine Homebuilding magazine showing a similar set-up:

021221072-2_med.jpg

Diagram from Fine Homebuilding magazine.

I tried using rolls of conventional peel-and-stick window flashing membrane, purchased from Home Depot and Mendards, but they performed poorly, even in unseasonably warm temperatures for February in Chicago.

I then switched to Grace Ice and Water Shield, normally used as a roofing underlayment along the first 3-6′ of roof edge.

grace-ice-water-shield

Purchased this box at Home Depot.

Since it came on a long roll about 4′ wide, my wife and I cut it down to a series of strips that could more easily be applied to the wall-top plate connection.

While the sun was out, the Grace membrane worked fairly well, especially when pressure was applied with a J-Roller.

grace-vycor-in-the-sun-ii

Grace Ice and Water Shield applied to the top of our wall — covering the Zip sheathing/top plate connection.

Unfortunately, the sun and warmer temperatures didn’t stick around long enough for me to finish.

sealing top of wall w: Grace Vycor in sun

Using a J-Roller to get the Grace Ice and Water Shield to stick better.

 

grace-vycor-in-the-sun

This Simpsons sky didn’t last long. In a matter of hours it was back to rainy, gray, and cold — typical Chicago winter weather for February.

When the weather went gray and cold again, we started to use a heat gun to warm up the Grace membrane, which had turned stiff and nearly useless in the cold.

wagner-heat-gun

Wagner heat gun for warming up the Grace membrane.

After wasting a lot of time and effort trying to pre-heat the Grace membrane before installing it, I finally relented and switched to the much more expensive (but also much more effective) Extoseal Encors tape from Pro Clima. Where the Grace membrane lost virtually all of its stickiness, the Extoseal Encors stuck easily and consistently, with the J-Roller just helping it to lay flatter and more securely.

extoseal-encors-as-gasket

Pro Clima’s Extoseal Encors available from 475 HPBS.

It was a case of trying to be penny wise but ending up pound foolish. Looking back, I would gladly pay an extra $300 in materials to have those hours of frustration back (including the time it took to run to the store and buy the heat gun, which turned out to be ineffective anyway).

installing Extoseal Encors on top of wall cloudy

Finishing up the top of the wall.

After finishing sealing the Zip sheathing-top plate connection on all the outside perimeter walls over the weekend, it was time for the trusses to be installed.

 

 

Trusses

first-truss-swinging-into-place

First truss swinging into place.

Zach let me stand by the front door rough opening and give the crane operator hand signals. It was a fun way to watch the roof take shape.

trusses-going-in-from-inside

Sammy, Zach, and Billy (out of view to the right), landing and setting the trusses.

Once the trusses neared the front door, Zach could signal the crane operator himself, so I was able to get some shots from just outside the construction fence.

 

starting-garage-trusses

Sammy, Zach, and Billy landing trusses on the garage.

 

long-view-of-crane-and-house-east-side

Setting the trusses on the garage — the basic profile of the house comes to life.

Once the trusses were on, and the guys had a chance to install the final top row of Zip sheathing (up to the bottom of the trusses on the exterior side of the wall), I could move inside to seal all the connections from the interior.

 

 

Top of Wall (Interior)

Because of the cold, the Grace membrane was beginning to lift at the edges in certain spots, so just to make sure it had a nice long-term seal, I went around the perimeter of the house and used a layer of Tescon Vana (3″ wide) tape to seal the edge of the Grace membrane.

sealed top plate from interior

Trusses sitting on Grace and Extoseal Encors (other sections of top plate), with the final row of Zip sheathing sealed to the trusses with HF Sealant.

The picture below shows all the connections involved: top of Zip sheathing meeting the roof trusses and the top plate of the outside wall:

sealed top of wall from inside

HF Sealant helps to air seal the Zip-truss and Zip-Grace/Extoseal Encors connections.

 

view of top row of Zip sheathing 1

Looking up at the top row of Zip sheathing attached to the outside edge of the raised heel trusses.

 

 

 

Shingles

We had to wait for shingles for quite some time. First we had to fire our GC’s, and then I had to find a roofer and a plumber (to make penetrations through the roof before the shingles went on). But before the plumber could even start, I had to get the Intello installed on the ceiling. And even before that, I had to figure out the insulation baffles, which I’ll talk about in a separate post.

It took awhile to find a roofer since they would have to make three separate trips for a relatively small job. The first trip was just to set down the Grace Ice and Water Shield at the edges of the roof, along with a synthetic roof underlayment (the consensus was that typical roofing felt wouldn’t hold up to long term exposure). As it turned out, it took weeks before the plumbers made their penetrations through the roof sheathing (literally the day the roofers showed up — a long, horrible story in and of itself that I’ll save for later).

synthetic underlayment at roof peak

Synthetic underlayment covering the ridge line until the shingles and a ridge vent can be installed.

The second trip out was to install the shingles on the roof of the house, while the third trip to install shingles on the garage roof could only happen after the Roxul on the exterior of our Zip sheathing was installed (in order to make a proper sealed connection between the wall of the house and the garage roof).

There weren’t many roofers willing to work with our unique Passive House sequencing, but Peterson Roofing was kind enough to take it on.

Grace ice and water shield rolling up after wind

Grace Ice and Water Shield rolling up on itself after the wind got ahold of it.

Unfortunately, the day after the guys installed the Grace membrane and the synthetic underlayment, we had a cold, blustery day. Once the wind grabbed the Grace membrane, the membrane rolled up on itself, turning it into a real mess.

Because of our recent past bad experiences with general contractors, I just assumed I was on my own, so I spent a couple of hours putting down new layers of the Grace membrane. When Peterson roofing found out, they were shocked I did it myself, and assured me I could’ve called them and they would’ve come back out. We were so used to people not following through, that low expectations meant it didn’t even occur to me to call them.

We initially were going to use Certainteed’s Landmark TL shingle, which mimics a cedar shake shingle profile, but Armando from Midwest Roofing Supply in Schaumburg, Illinois was kind enough to take the time to walk me through the options available, and explained that because our roofline isn’t steep, only the neighbors from their second story windows would get to appreciate the effect. He recommended we save some money, while not giving up on quality or durability, and go with the Landmark Pro product.

shingles being installed w: vents

Shingles going down on the roof of the house.

The shingles went on quickly since we have a relatively small and simple roof. In addition to the aesthetic leap the shingles made on the appearance of the structure, it also meant I didn’t have to go around cleaning up the subfloor every time it rained.

Although the synthetic underlayment worked pretty well at keeping the rain out, if there was significant wind combined with rain, the water easily found its way under the underlayment where it could then drip and fall on the subflooring below — pretty depressing showing up to the job site after a hard rain knowing I was going to spend the first hour just cleaning up and looking for leaks.

roofers shingling south side

Seeing this felt like a tremendous amount of progress was being made. It also meant an end to our roof leaks on the interior.

 

shingle installation progressing

Shingles going on quickly.

After they cut the opening for the ridge vent, but before it was installed, I managed to get this shot from inside:

attic just before ridge vent installed

Attic as cathedral.

 

 

The Passive House Nightmare: Part 3

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This can’t be happening again…

It is February of 2017 as I write this.

This project began for us back in the summer of 2014 — nearly three years ago — when we first sat down with Brandon Weiss in what was then his new office in Geneva, Illinois. As detailed here:

The Passive House Nightmare

things did not go well for us with Brandon or his company Evolutionary Home Builders.

After we decided to move forward and try to complete what we started, the question became:

Who do we hire as our next builder?

After our interactions with Mark Miller and Katrin Klingenberg, detailed here:

The Passive House Nightmare: Part 2

PHIUS (Passive House Institute US) did not seem like a resource we could utilize — the Passive House world is small, smaller still when you reduce it to a single geographical area like Chicago and its surrounding suburbs. And the thought of interviewing conventional builders, and trying to convince one to take on the detail required in a Passive House level build, seemed overwhelming.

As a result, we decided to go with two guys close to home who have conventional building experience.

The logic underlying the relationship was that they would GC the build, taking care of all the conventional building details, while I took care of all the Passive House details.

Unfortunately, this proved fruitless.

 

flooded basement

 

Events revealed they didn’t have the requisite skill set necessary to complete the job, and we have subsequently taken over the project ourselves. It’s taken weeks to get things back on track, hence the delay in posting anything new regarding the progress of the build.

 

job-site-shut-down-west-side

 

When the build is complete, I’ll return to this matter, offering more details that will hopefully help other consumers who want to build a new house avoid our unfortunate experience.

 

new beginnings

New beginnings.

 

The really sad thing is there are quality people who make a living as general contractors, but unfortunately it remains a minefield out there for consumers without meaningful connections. If you don’t already know the answer to the question ‘Who should build our new house?’ before you start the process, then it’s truly a case of caveat emptor. And if things should go poorly, you will feel like you’re on a very lonely island.

 

relentless

Relentless.

 

Details to follow…

Framing (Air Sealing #2)

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Mudsills

In a conventionally built home, mudsills are typically an area of significant air leakage (if you’ve ever seen sill sealer — a thin layer of foam normally used to address this lumber-concrete connection — under an actual mudsill, you can visibly see just how poorly it performs).

In contrast, after reading about various strategies employed to reach the Passive House standard of 0.6 ACH for air tightness, I decided to use the approach developed by architect Steve Baczek specifically for mudsills.  There is an excellent article in Fine Homebuilding magazine that describes the details, and there is a companion series of videos available on Green Building Advisor (after the first video, membership is required, but it’s well worth it for this series of videos, as well as all the other information available on GBA).

We didn’t use the layer of poly, or the termite shield, but the remaining details we followed fairly closely. And we did make one product substitution — instead of using the Tremco acoustical sealant, we decided to go with the Contega HF sealant (less messy, lower VOC’s, and skins over and firms up enough to apply the Pro Clima tapes, all while remaining permanently flexible like the Tremco product —  these products are available at foursevenfive.com).

bill-and-phil-setting-up-chalk-lines-for-mudsill

Billy and Phil setting up chalk lines for the mudsills.

 

nils-running-bead-of-sealant-before-mudsill-goes-down

Nils applying a thick, continuous bead of Contega HF sealant, including around the bolts, before the 2×6 pressure treated sill plate gets installed with a BG65 gasket underneath.

 

ct-gasket-close-up-on-srap-board

BG65 gasket from Conservation Technology stapled to the bottom of a scrap piece of sill plate.

 

ct-gasket

BG65 gasket rolled up in the box it shipped in.

Sammy and Billy stapling the BG65 gasket to the sill plates before installation:

 

mudsill-squeeze-out

Mudsill installed with some squeeze out of the sealant.

Installing the sealant on the mudsill (interior/exterior edges, seams, and bolts/nuts/washers) required some gymnastics:

 

selfie-by-window-buck

In theory, she’s helping me.

 

mudsill-with-gasket-and-sealant-garage-from-inside-basement

Mudsill after installation: sealant covering sill plate – BG65 gasket – concrete connection, with seams filled.

Once again, based on Steve Baczek’s design — going from exterior to interior — here is our Mudsill Air Sealing Approach:

  • Bead of sealant on the exterior side of the 2×6/foundation connection
  • BG65 gasket under the sill plate — along with a thick bead of sealant under the gasket and sill plate (including around bolts)
  • Bead of sealant on the interior side of the 2×6/foundation connection
  • And then, finally, a taped connection on the interior side of the 2×6/foundation connection as a last line of defense against air infiltration (which I’ll complete once all the trades go through the interior of the house).

The approach assumes I will make mistakes at certain points with each layer of air sealing, so I’m counting on these layers of redundancy to protect me from myself. Again, this is the first time I’ve ever done this, so the theory is that even if I make a mistake in one area, it’s unlikely that I will make a mistake in exactly the same spot with successive layers of air sealing.

Obviously I’m trying to do my best with each layer, but I like the idea of added layers of protection (a Passive House obsession), especially when accounting for the long-term life of the structure. Even if each layer could be installed perfectly, presumably each layer will fail eventually at different times and in different places (hopefully 50-100 years from now if the accelerated aging studies are accurate), so hopefully these layers of redundancy will help maintain significant air tightness far longer than if I chose to use fewer layers. Plus, I’m enjoying sealing everything up, so I don’t mind the process, which always helps.

For larger gaps (not just for mudsills, but anywhere in the building envelope), roughly 3/8″ inch or larger, I am utilizing backer rod to help fill the gap before applying sealant.

This is what it looks like:

 

The backer rod (readily available at any hardware store) makes life easier for caulks and sealants — less stress on the connection between materials as the inevitable expansion and contraction occurs in the gap.

Hammer and Hand’s Best Practices Manual has the best explanation for their use that I’ve come across:

“While the humble sealant joint may be uncelebrated, it is vital to building durability and longevity. Proper installation is key to sealant joint integrity and function throughout a life of expansion and compression, wetting and drying, exposure, and temperature fluctuation.

Note: Because sealants are just as good at keeping moisture in as they are in keeping it out, placing a bead of caulk in the wrong location can result in moisture accumulation, mold and rot, envelope failure, and hundreds of thousands of dollars in repair and remediation. If we know anything, we know that building envelopes will get wet – the question is, “where will the water go?” Make sure you know the answer throughout construction, especially as you seal joints…

2-1a-500x3892x

Diagram courtesy of Hammer and Hand’s Best Practices Manual.

… Joint Rule of Thumb: Sealant should be hourglass-shaped and width should be twice depth (shown in diagram).
Backer rod diameter should be 25% larger than the joint to be filled.
Joint size should be 4x the expected amount of movement (usually about 1/2” of space on all sides of the window casement).
Ideal joints are within a range of 1/4” at minimum and 1/2” at maximum. Joints outside this range require special design and installation.
Always use the right tool: sealant is not caulk and should never be tooled with a finger (saliva interferes with bond).
Substrates need to be clean, dry, and properly prepared (primer if necessary).
When dealing with thermally sensitive materials, apply sealant under average temperature conditions because joints expand and contract with changes in temperature…”

backer-rod-by-header

Example: Piece of backer rod being inserted into gap between header and 2×6.

 

garage-mudsill-w-gasket-and-sealant-corner

It’s not visible, but the wood-concrete connection at the side wall has a piece of backer rod embedded between the two materials, making it easier for the sealant to bridge the gap over the long term.

 

 

Air Sealing: Rim Joist – Floor Joist – Mudsill Connections

installing-floor-joists-w-bill-johnny

Billy and Johnny installing the floor joists.

Since there was time between completion of the rim joist/floor joist installation and the installation of the sub flooring (a weekend), I took the opportunity to seal up all the visible connections. Once the subfloor goes in, these connections are still accessible from inside the basement, but the space to work in would be really cramped and uncomfortable (at least I thought so).

rim-joists-box-before-caulk

Rim joist – floor joist – mudsill connections prior to sealant being applied.

The same areas after applying the sealant:

More gymnastics required while applying the Contega HF sealant:

I found the silver Newborn sausage gun (photo below) worked great for thick beads under the mudsills, but the blue gun worked even better for all other seams. Because the blue gun utilizes disposable tips, it was easy to cut the tip to exactly the size I needed, thus using (wasting?) less material (and hopefully saving a little bit of money). An added benefit of the disposable tips is less time required for clean up at the end of the day (always a good thing). Both guns work great, and appear to be really well-made, although I would probably only buy the silver one again if I consistently needed a fat bead of sealant.

newborn-sausage-guns

Newborn sausage guns I found on Amazon. The blue one works great for thin beads, the silver for thicker beads (e.g. under mudsills).

In the photos below, I filled larger gaps with either backer rod, or in the case of the largest gap, bits of pulled apart Roxul Comfortboard 80, before applying the sealant. Since this is the first time I’ve done this, these are the kind of connections that I failed to anticipate beforehand. They are definitely worth planning for.

The temptation is to just fill these kinds of voids with sealant, but for the long-term durability of the connection backer rod or some kind of insulation stuffed into the gap is a better solution. Filling the voids before sealing doesn’t take much additional effort, so it’s definitely worth taking the time to do it right.

 

 

Knee Walls Installed

Because our lot is sloped, the plans called for a series of knee walls:

knee-wall-going-up

The guys installing the knee walls (left to right: Johnny, Nils, Sammy, and Billy).

When I saw the first piece of Zip about to be installed, I realized the bottom edge, which is exposed OSB, would be sitting directly on top of the Roxul on the foundation. While it’s unlikely that water will find its way to this edge (the flashing for the wall assembly will be installed over the exterior face of the Zip at the bottom of the wall), it seemed like a good idea to tape this edge with the Tescon Vana for added protection and peace of mind (even if it only protects this exposed edge until the rest of the wall assembly is installed).

zip-first-piece-attached

First piece of 7/16″ Zip wall sheathing installed.

Knee wall pictured below had all exposed seams in the framing lumber filled with the Contega HF sealant before also applying the Tescon Vana tape, all of which was done prior to the Zip sheathing being installed. The sealant takes about 48 hours to cure enough before you can effectively cover it with the Pro Clima tapes (something to consider when setting up scheduling goals).

20170105_121618

Knee wall being covered in Zip sheathing.

 

zip-on-framing-covering-tescon-vana-w-roxul-below

Close up of knee wall with Zip sheathing and sealed seams.

For the bottom, exposed edge of the Zip sheathing, I cut the Tescon Vana tape like I was wrapping a present…

Once the Zip sheathing was installed on the knee walls, I could move into the basement and seal up the connections between the Zip and the framing members, in addition to hitting any seams in the framing itself.

Once the house gets closed in, I will go back and tape the connection between the top of the foundation and the mudsill for one last layer of protection against air infiltration.

sealing-up-the-inside-of-the-knee-wall-stud-bays

Knee wall with Zip sheathing after sealing up all the connections.

 

 

Subflooring

We decided to use Huber’s Advantech Subflooring after years of reading about it in Fine Homebuilding magazine, and based on the online comments from installers who see the added benefits that come with what is an admittedly higher price point. For instance, it’s more resistant to moisture, so it should produce more stable, flatter flooring (e.g. hardwood or tile) when the house is complete, in addition to preventing annoying floor squeaks.

Billy Phil Nils first pieces of subflooring

First sheets of subflooring being installed by Billy, Phil, and Nils.

In order to maintain a high level of indoor air quality (IAQ), we’ve been seeking out low or no VOC products. So, in addition to the Advantech subflooring, which is formaldehyde-free, we chose the Liquid Nails brand of subfloor adhesive (LN-902/LNP-902) because it is Greenguard certified. Another great resource for anyone trying to build or maintain a “clean” structure is available at the International Living Future Institute website: The Red List

liquid-nails

The product takes much longer to dry when it’s cold and wet outside — at least 2-3 days in our experience (sometimes even longer). It’s nice to see more “green” products showing up in the big box stores, rather than having to always special order them.

 

view-of-water-tower-from-kitchen-doorway

Standing by what will be the kitchen door. The subflooring was installed with nails and Liquid Nails subfloor adhesive.

 

rim-joists-at-outside-corner-sealed-up

Corner of our slowly growing wall assembly. The connection between the subflooring and the top of the rim joists was eventually sealed with the Contega HF sealant. 

Basement slowly being covered by subflooring:

 

 

Walls Go Up

subfloor-done-blank-canvas

Our blank canvas.

Our wall assembly is almost entirely based on Hammer and Hand’s Madrona House project, which I discuss here: Wall Assembly

In preparation for construction, I built a mock wall assembly in order to easily explain to anyone on site how the various components should go together. It also gave me a chance to practice using the Contega HF sealant, along with the various Pro Clima tapes from 475 High Performance Building Supply.

It’s been exciting to see the walls go up, incorporating the many details in the mock wall assembly.

men-at-work

Men at work: Zach, Phil, and Sammy laying out the walls.

 

zip-going-on-the-walls-w-bead-of-adhesive

Zach and Phil installing the Zip sheathing over the framing.

 

zip-sheathing-w-phil-putting-on-continuous-bead-of-adhesive

Phil laying down a consistent and continuous bead of construction adhesive (trying to avoid a bead that runs back and forth between fat and thin), before the Zip sheathing is installed.

 

wall-being-prepped-w-tescon-vana-on-seams

We were fighting the rain, ice, and mud, but I was able to get the Tescon Vana tape over some of the seams in the Zip sheathing before the walls went up.

 

sealant-on-nail-holes-in-zip

Sammy and Billy help me apply the Contega HF sealant to each nail hole, and then make it lie flat with a swipe of the spatula, so the Tescon Vana tape that will be applied later will also lie flat.

 

zip-sheathing-prepped-w-tescon-vana-and-sealant-on-nail-holes

Section of wall nailed, taped, and nail holes caulked — ready to be raised up.

The final step before the walls were raised was to staple the B75 gasket to the bottom of each sill plate.

billy-zach-sammy-south-wall

First section of wall going up: Billy, Zach, and Sammy doing the heavy lifting.

 

phil-zach-plumb-sammy

Zach establishes plumb, while Phil readies to make the wall secure.

 

all-together-south-wall

The guys continue with the south walls.

View from north-east corner of house, and the guys framing in the shadow of the water tower:

The only section of wall where the B75 gasket rolled up on itself is shown below — no doubt because this was the most difficult section to get into place because of the stair opening. Otherwise, the guys had no issues with the gasket.

Even on this wall where the gasket did roll up on itself, I will cut off the excess that ended up on the interior side before sealing the connection with the subflooring, and then spend some time filling the void on the exterior side with backer rod and sealant as well.

east-wall-at-stairs-in-place-gasket-roll-up

Zach is the only dedicated, full-time framing carpenter on the crew (the other guys do a variety of carpentry-related work). He has a production background, and it shows with the energy and ease with which he works. He clearly enjoys what he does for a living (Zach, Sammy, and Billy). Sammy and Billy may not realize it yet, but they’re learning a lot from him (even if he does razz them all day long).

Below you can see some of the junctions where different materials meet, and the effort that’s going into air sealing these inevitable gaps: sealant at rim joist corners, rim joist – subfloor connection, and gasket under the wall sill plate:

wall-at-corner-w-b75-gasket-underneath

Wall is up.

 

wall-at-corner-w-b75-gasket-view-down-ext-side-of-wall

Same corner as above, but looking down exterior side of the wall.

We’ve tried very hard to keep foam out of the wall assembly and the overall structure itself (based on environmental concerns), however, one place where it did find its way in was the insulated headers for above our windows and doors:

billy-and-sammy-insulated-headers

Billy and Sammy putting the insulated headers together.

 

4th-wall-missing-from-backyard

End of the day. The fourth wall awaits.

 

east-facade-w-zip-sheathing

First look at what will become our front facade.

Once the perimeter walls were up, I went around with an impact driver and decking screws to tighten the connection between the Zip and the framing members, especially at the top of the walls. Although the Liquid Nails adhesive helps a lot, it still makes for an imperfect connection between the sheathing and the framing members:

top-of-wall-assembly-looking-down-gap-w-nail

Looking down at the top plate. The visible gap is between the side of the top plate and the Zip sheathing. I was able to close gaps like this one at the top of the walls using decking screws. The decking screws also closed similar gaps around window and door rough openings. This should make sealing these areas easier, and the connection more durable.

 

leaning-over-top-of-zip-sheathing

Leaning over the top of the wall to install the decking screws.

Having seen construction adhesive and nails in action, I would recommend a glue-and-screw approach if you’re trying to fully maximize the tightness of the connection between the sheathing and the framing.

sealant-with-water-tower

Nice view as I apply the sealant.

 

blue-chicken-pox

My wife giving our Zip sheathing blue chicken pox with the Tescon Vana tape in order to seal all the nail holes.

 

tescon-vana-embedded-in-ice-on-sill

It’s difficult to see, but this tape is embedded inside a sheet of ice. It rained overnight, before turning to ice. We’re asking a lot of these tapes and sealants. This piece of tape looks like fingertips holding on for dear life.

 

beast-looking-at-view-from-br-for-1st-time-close-up

The Beast gets a first glimpse of the view from her bedroom window.

 

pro-clima-pressfix

I was wondering why I would ever need more than one of these. Now I know — bent, scratched, and cracked, the Pressfix from 475 HPBS did its job well.