Buddy from Fort McMurray told me to use spray foam in my rim joist

He swore by that Great Stuff stuff for sealing up the basement rim joists. Did the whole job last fall and now I'm worried I trapped moisture in there. Anyone else deal with mold after using spray foam down there?

3 comments

3 Comments

emery_lopez28d agoTop Commenter

I mean, "caught it early" is the key there, but maybe it's not just about mold. Idk if anyone's thought about this, but spray foam can actually make your rim joist rot from the outside in if there's any gaps in your siding or brick above it. Water gets behind the foam and can't dry out, so it just sits there against the wood all winter. I'd poke a couple small holes in the foam down low and check with a screwdriver to see if it's damp back there before it gets worse.

umathompson29d ago

Oh man that's a tough spot to be in. I hope it's not too bad down there and you caught it early.

holly_walker761d ago

You mentioned "caught it early" and that reminds me of something that happened to my neighbor. He found a little bit of mold in his crawl space and thought he'd nipped it in the bud. So he just sprayed some bleach water on it and called it good. Six months later he had a full blown rot issue because the source was a slow drip from a pipe in the wall. He ended up having to tear out a whole section of subfloor and replace it. That early fix cost him way more in the long run. Sometimes the small stuff is just the tip of the iceberg.