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Choosing between spray foam and fiberglass batts for my attic in Sherwood Park was a real headache
I went with the spray foam for about $4k, and my heating bill dropped by almost 30% this winter, but now I'm wondering if anyone else has had issues with it making the roof sheathing too cold.
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hall.viola6mo ago
My cousin in St. Albert had that exact problem with his spray foamed roof deck. The foam sealed it up so tight that moisture from the house got trapped against the cold wood in winter. He found mold spots on the north side sheathing after two years. You need a really good vapor barrier on the warm side, and even then, I'm not convinced it's enough for our climate. That 30% savings might cost you a new roof down the line if the sheathing rots out.
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viola_cooper626mo ago
But is mold really that common? Seems like a lot of people get foam done without any issues.
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eric_carr5mo ago
Not just the vapor barrier though, what about the framing itself? If the lumber wasn't bone dry when they foamed over it, that moisture gets trapped in there too with nowhere to go.
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