Canned spray foam: a reliable air seal?
Simple question, folks … Canned spray foam is widely used to seal between a window frame and it’s rough opening and around all sorts of envelope penetrations. But are canned spray foams open or closed cell? Does this vary by product? And if they’re open cell (my hunch based on stated R values), then are they reliable air barriers if they’re less than 3.5 to 5.5 inches thick? See …
I’m guessing that a lot of window installations get canned spray foam that doesn’t reach the required thickness and so doesn’t really give an airtight seal.
We’re working out air barrier specs with builder of our new home, and I’m wondering if we should specify some minimum thickness of canned spray foam, wherever it’s going to be used.
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