Choices in Window Installation

The window installation has been one of the more difficult issues to deal with.  The first part of that issue was deciding which product/method to use to flash the windows and achieve the necessary level of air-tightness.

We tested three products/methods on the basement windows.  The first was Tremco’s ExoAir Duo Membrane.  This is basically a flashing tape that is applied to both the inside and outside of the window jamb gap.  Half adheres to the window, and half adheres to the jamb, thereby completing the seal.  Spray foam is applied in between the two (before the second side is applied.  This product seemed to be the least favorable.  First, it was difficult to get the tape to seal to both surfaces without undesirable waves.  But the bigger issue was that it seemed almost impossible to get the spray foam to fill the gap without pushing the tape outward.  It was obvious that this would make it difficult to properly trim out the window box; at least not without significant difficulty.  We estimated that it would have cost approximately $750 for enough of this product to do all 19 windows in the house.  Here’s the best and worst of what it looked like:

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The second product that we considered is also made by Tremco.  It’s called the Exo Air Trio, and seemed to be a much more effective product.  It basically consisted of a a compressed foam band with adhesive on one side.  It is applied to either the window or the jamb.  Once unrolled, it begins to expand, so you have to plan out the installation a bit.  But the expansion rate is rather slow, so it’s not a mad rush.  Once fully expanded, the foam completely seals all of the gaps between the window and the jamb.  It looked pretty effective, if not a bit amazing.  The biggest downside was the estimated $1800 price tag to do all of the windows.  Here’s what the installed product looked like:


The third option (the option that we went with) uses a three-part solution by Prosoco.  Unlike the other two products, the Prosoco solution seals the gap and flashes the window.  The first part of the process involves the application of Prosoco R-Guard Joint and Seam Filler, which is described as  “a fiber reinforced fill coat and seam treatment.”  It basically appears to be a pink, fibrous, rubber caulk.  It’s applied to all of the seams in the rough opening.  After that, the R-Guard Fast Flash was applied to the entire opening (and the exterior of the opening).  Like the Joint and Seam Filler, it’s applied with a caulk gun.  But then it’s smoothed out with a spatula to create a consistent rubber-like covering over the entire area.  Once dry, it really leaves one with the impression that the opening will be impervious to water and moisture:


Then the window is installed, and an appropriately sized backer rod is installed in the gap surrounding the window on the interior surface.  The final step is the application of the R-Guard Air Dam product to the face of the backer rod:

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All in all, it appears to be a pretty bullet proof system that interplays well with the Zip System sheathing, and should serve us well.  On top of it all, we estimate that it will cost us somewhere around $500 to cover the installation of all of the windows.


External Framing Completed

The basic frame and all Zip sheathing was completed on September 16th.

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In the two photos below, you’ll see how the Zip is being wrapped over the top of the second floor walls.  Once we prep for the future attic insulation (we need to install some type of baffle to retain the 18″ of cellulous),  Zip will be installed on the rest of the second floor ceiling and the seams will be taped.  As can be seen in the following photos, the finished side will face down.  It could have gone either way, but since the tape will be placed on the bottom, this seemed to make most sense.

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That’s 1/2″ Zip in the photos above.  The same thickness we used on the exterior walls (we used 5/8″ Zip on the roof).  Looking back, we could have saved a bit of weight and money by using 7/16″.  I was a bit concerned with the ability of the roof trusses to hold the weight of the drywall, zip, and 18″ of insulation.  But they’re engineered to support 10lbs/sqft, which provides a reasonable margin of safety, as the weight of the drywall, Zip, and insulation amounts to less than seven.

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The combination of perspective, background lighting, and lack of windows and porch make the house look mighty small.  Hard to believe that its over 2,000 square feet.


The rest of the Zip was taped a couple of days later.  The Zip tape dispenser/roller proved difficult to use effectively.  The roller seems to have a slight crown that makes it difficult to seal the edges and causes the roller to drift.  But the job was completed:

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Carrying the Vapor Barrier Over the Basement Wall

As I discussed in my last post, our intent is to bring the vapor barrier from the basement slab, up the inside of the basement wall, then over the wall to the outside of the building, and then up the outside of the wall via Zip System sheathing.  But to give the basement walls as much time as possible to dry, we won’t be covering the basement walls until the house is completed (which I anticipate to be sometime next spring).  To prepare for that, we needed to bring the barrier over the top of the basement wall now, before the framing begins.  As you’ll see in the following photos, we did this with the same peel and stick membrane used on the outside of the basement walls:



And after:

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Because the membrane is a bit challenging to work with, we used the following process to complete the task:

1. The membrane comes in 36″ wide rolls (75′ long).  So we cut a length in half (18″), which was the perfect width to cover the top of the walls (which are 15 1/4″ wide).

2. We then cut each 18″ strip in half.  This precluded the need to try to fit a single piece over the sill bolts.

3. Finally, we laid each strip down, lapping the inside strip over and down the inside wall (about an inch-and-a-half) and the outside strip over and down the outside wall.  We were able to cut around the sill bolts as we went along, and we matched the pieces up fairly easily, with only occasional minor gaps between the two.  Since the slight gaps that existed here and there ran down the middle of the walls, we knew that the sill seal would cover them.

Here’s a photo of the wall after the sill seal was in place:

IMG_0055 The product we used is Protecto Wrap Premium Energy Sill Sealer. It’s a 3/8″ closed cell polyethylene foam with an aggressive self adhesive waterproofing membrane that conforms and seals off the voids and irregularies between the top of the foundation and sill plate.  Because the walls are wide and we used a 2″x10″ sill plate, we used two side-by-side strips of 5 1/2″ sealer.  We also put a bead of caulk down each strip before placing the sill plate on top of it and bolting it down.

The Sill Sealer doesn’t come cheap.  It can be purchased for about $40 per 75′ roll (or $1.60/lf).  But its thickness and bottom adhesive did give us confidence that we’ll seal the irregularities that are inherent in the foundation sill.  Hopefully, it will make it that much easier to meet the .6 @ 50 pascals target.


The Basement Slab, Insulation, and Vapor Barrier

As I indicated in the last post, we chose a third option with regard to the vapor barrier in the basement.  If anything appears clear to me, it is that, like so often in life, there is no perfect solution to this issue.  Rather, it’s a balance of time, money, and effort.  What we ended up doing was this:

Once the four inches of gravel was sufficiently leveled with a laser level, they placed three two-inch layers of XPS Green Guard Foam (R-30) on top of it, laying each level perpendicular to the one below it.  This is a photo looking in from the Bilco door opening.  They’re working on the third layer:


Once that was completed, they covered the foam with a layer of 16 mil polyurethane (i.e. the vapor barrier, and taped it to the ICF foam. The lally columns sat directly on the footer pads.  So we taped the poly to the columns, and then wrapped the columns with a kind of bubble insulation that could later be ripped out (after the concrete was poured) and filled with spray foam:


We initially anticipated running the poly up the wall and taping it above the concrete so it would be easy to connect to the barrier that we will run up and over the walls.  But that idea was nixed because it would make it difficult to chalk a line for the leveling of the slab.  While not a perfect alternative, we feel that taping the poly to the ICF at the point where it meets the sub-slab foam will work fine.  When the house is completed (eight or nine months from now), we’ll bring the vapor barrier from the top of the slab up to the top of the basement walls, and tie it into the barrier that we will (next week) place over the top of the foundation walls.  Essentially, that will leave only one avenue for sub-grade vapor to enter the house; it would have to come up from the footers through the foundation walls and then through the EPS ICF foam and into the slab.  We don’t see that as a serious concern because a) the potential area that is open to vapor infiltration is less than 50sqft (the 132 linear feet of the edge of the 4″ thick slab), which amounts to less than 1% of the entire building envelope (which I estimate to be over 6,000sqft), b) while not a vapor “barrier” (i.e. less than .1 perm, the EPS foam is certainly a vapor retarder at less than 1 perm, c) even without the EPS vapor retarder, my research indicates that 50sqft of 4″ concrete can only allow the transmission of a maximum of about 2 tablespoons of water vapor in a 24 hour period, and d) the Form-A-Drains provide a more favorable route for water vapor than the cement itself. I’m sure my conclusions can be debated.  But I’m comfortable with them.

Once the poly was properly taped, the concrete was poured:


Note the detail at the Bilco door entrance:

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That was a misstep in that it was just one of those small details that didn’t make it into the plans.  If left as poured, there would be no “thermal break” (i.e. insulation) between the Bilco well and the slab.  Fortunately Hugh caught it before the Bilco was installed, and the correction was relatively easy; an hour spent with a grinder and 2″ of XPS: