Monday, September 2, 2013

Sealing up the top of the Back Dormer

The top of the back dormer is one area I've been meaning to seal up. The carpenter crew has taped the outside of the sheathing, but it needs more air sealing. On the front dormer I just sprayed a butt load of "Great Stuff" caulk which looks ugly and I worry that it will open and crack with movement of the house. That is why I have used so much of the Prosoco Joint and Seam sealer cauking sealing most of the interior wall framing elsewhere in the house.

Here is how I have sealed the back dormer air gaps.

When you can see daylight, you know that there is an air gap.
Another view of the air gaps at the top of the dormer. Not a great photo, but you can still see the problem.

You can see the gap clearly here. 

The gaps at the top of the back dormer where the upstairs bathroom will be located were pretty large. I wanted to do a better job that just caulking with "Great Stuff". John cut some beveled polyiso foam boards for me that I was able to fit into these areas. I did bed the foam boards in "Great Stuff" foam so they are secured in place.

I like this solution to sealing gaps much better than just pure blobs of foam. It is a little fussy to do though. If John didn't have his shop right here with a table saw capable of beveling the edges and a radial arm saw making it easy to cut stuff to length, I think I would have gone with the blobs of foam solution.

I will probably tape the top side of the foam boards to ensure that they are well sealed to the framing.
Much better, don't you think?

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