Why does nobody talk about how bad spray foam insulation can go wrong

I sprayed a whole attic in my duplex back in March and it looked perfect at first. Three months later I noticed a weird smell and found moisture trapped behind the foam near the roof vents. Turns out I missed sealing some gaps around the soffits and it caused condensation. Had to rip out a 6 foot section and redo it with rigid foam boards instead. Cost me an extra $200 and a full Saturday. Has anyone else run into moisture issues with DIY spray foam kits?

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2 Comments

kimreed2mo ago

Depends on the prep work a lot, user error is usually the real problem there.

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xenagarcia2mo ago

That 6 foot section you had to rip out is brutal man, I feel that. The thing about prep work though, it's not always straightforward with those DIY kits. I used the same kit in my garage last year and made sure the soffits were sealed tight, but I still got moisture because I didn't account for the humidity coming from the attached laundry room. The closed-cell foam creates a vapor barrier that can trap moisture if there's any air leak you missed. It's not just about user error, it's about how tricky it is to get a perfect seal in an attic with weird angles and existing stuff in the way.

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