kimchi & kraut

Passive House + Zero Net Energy + Permaculture Yard

Roof Details (Air Sealing #3)

0

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.

 

 

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.

 

 

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: