Can you apply spray foam over exterior rigid foam?
We are planning to build a house located in Montreal where the weather in the winter is relatively cold and swings to hot and humid summers. We wanted to build a wall system of R40.
A lot of builders here in Montreal are spraying the exterior of the building with 1″ of spray foam over plywood in order to prevent air infiltration and then filling the 2X6 studs with normal fiberglass.
From what I have read the 1″ of exterior foam is not enough to prevent condensation issues on the plywood.
Question: is it possible to install 2″ of rigid foam such as XPS or EPS and then add 1″ of spray foam for to seal the building? I would then install normal fiberglass batts in the studs.
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