Tried spray foam vs foam board for sealing a basement rim joist

Last month I used spray foam in a can to seal the rim joist in my duplex over on Maple Street. It was a complete mess - dripped everywhere, took forever, and I used 8 cans at $7 each. Last weekend I tried rigid foam board cut to size with canned foam for the gaps and it took maybe 45 minutes total. Has anyone else found that combo way easier?

2 comments

2 Comments

milaprice14d agoMost Upvoted

Solidarity from someone who also learned this the hard way last year. @troythompson nailed it with the board-plus-canned-foam method, total game changer for rim joists.

troythompson14d ago

Wait did you try spraying the big gaps full of foam first? That's where people mess up. Foam board with canned foam for the edges is the only way to go for rim joists. I did my whole house that way last fall and it took one afternoon. The key is cutting the board just a bit small so you can squirt the canned foam around the perimeter. That seals it tight and you don't waste product. Plus if you ever need to get back in there for wiring or whatever you can just pull the board out and cut the foam. Spray foam in a can is great for tiny gaps but not for filling whole sections. That combo you used is what most pros do around here.