Interested in spray foam insulation for attic floor

Discussion in 'Insulation and Radiant Barriers' started by strategery, Feb 4, 2012.

  1. Feb 4, 2012 #1




    Active Member

    Dec 22, 2011
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    I have an old 1000 sq ft house in the Midwest. I have a combination of insulation materials up there- fg batts, blown fg, blown cellulose. I need to increase my attic insulation to at least r 49. Now it's about 30.

    I am considering doing this myself. My concern is what TYPE of spray foam is right for the attic floor? Closed cell is a vapor retarder that allows some permeability. Will that trap moisture underneath rotting the wood joists? Would an open cell foam be better for allowing drying?

    I try to reduce indoor humidity as much as reasonably possible. I just have this one concern re: foam. From a performance standpoint, I think it's going to be way superior to fg or cellulose.

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