Best Way to Seal a Large Gap Around a Bathroom Exhaust Vent?
Asked by CuriousTraveler123
I just installed a new bathroom exhaust fan and I need to make sure it's properly air sealed in the attic. However, the gap surrounding the vent is too large to fill with spray foam alone. I've come across the idea of using rigid foam board—should I cut a piece to place directly over the gap and then use spray foam around the edges, or should I cut a piece that fits into the gap with the spray foam applied on top? Also, I've included a link to the photo for reference: https://imgur.com/a/sFYFK4j
Answers
I recommend using high density foam that comes in rolls with adhesive backing to fill the gap. Once it's in place, taping around it with aluminum tape can help create a solid air and moisture barrier. That approach has worked well for me! You can also spray some Great Stuff foam over the foam piece to ensure it's sealed tight.
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You might want to try using Gorilla Tape or FlexSeal Tape for a quick fix. They can help create an air seal, but make sure to check their effectiveness over time. It's always good to double-check how well those hold up!
InquisitiveMind88: Will that really create a reliable air seal?
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DIYQueen99: That sounds like a solid plan! I have aluminum tape left over from a previous project, too, so I'll definitely give that a try.