Moisture Concerns when Sealing Air Leaks in a Brick and Block House
I’m working on a brick and block constructed house in south east Pennsylvania. The house was built in the 60’s and does not have any insulation in the walls. The cross section of the wall consists of 4″ of brick, then 4″ of block, then 1″x3″ furring strips, then drywall. The cavity created by the furring strips basically creates an air chute that runs from the basement to the attic.
I know that there are expanding foam products that you can pump into the 3/4″ cavity to insulate this space, but I was planning on simply sealing off the cavity at the top and bottom with canned spray foam. This would attempt to create an insulated air cavity or at the very least help prevent some air leaks in the house.
My concern with this approach is that the moisture from the brick and block will build up in the cavity between the block and the drywall (similar to what can happen in a stud wall / brick veneer system that isn’t properly vented). With the area sealed off (at the top and bottom) there would then be no way for this moisture to “ventilate” out of the wall cavity.
Does anyone have any experience with this approach either positive or negative? Any insights would be much appreciated.
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Replies
Victor,
Without any insulation or vapor barrier, your wall will dry quickly to the interior. You won't have any moisture problems, even if you perform the air-sealing work you propose.
That said, your wall would perform much better if you insulated it.
Martin,
Thanks for your quick response. I agree that the best long term solution is adding full insulation to the cavity (or more extensively - building the walls in and adding insulation). This would be more of a phase 2 project. I just wanted to make sure that this short term approach did not cause any problems.
Thanks again, I appreciate your input.