Foam sandwich in Canada
I have a question about upgrading insulation in our home we’re having built in Southern Ontario.
The “normal wall” the builder uses is 1″ of XPS rigid insulation on outside, installed over OSB, on top of a 2*6″ wall on filled with R18 fiberglass bat. Naturally, the whole thing is sealed on both sides, with tape on the XPS and poly sheeting on the inside.
I want to replace the fiberglass with closed cell spray foam, a full 5″, to really up the insulation factor, and not screw up anything the builder wants to do, as this isn’t really a custom home, but they’re willing to accommodate my desire for energy efficiency within limits.
However, it seems like either wall construction can’t dry anywhere… Won’t this rot??
What’s the right way to deal with this?
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