Which way should the foil facing on polyiso rigid foam face?
Correct me if I’m wrong, but shouldn’t the foil facing on polyiso face the interior in climate zone 5 to help retain heat? It will be used on basement rim joists. The heating season is obviously longer than the cooling season.
Furthermore, should I leave an air gap between the foam and the wood or should I place the foam directly against the wood before spray foaming the perimeter?
Lastly, should I seal the perimeter of the rim joists with the one part foam prior to installing the rigid foam and spraying around the perimeter of that?
I was thinking of not sealing the perimeter prior to installing the rigid foam to give any moisture entering the cavity an avenue to escape. Although no moisture should really be entering the cavity from the inside and to the best of my knowledge, polyiso is vapor-impermeable (not sure about the 1 part foam but I think it is vapor-permeable).
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