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Moisture trapped by rim joist foam

14 years ago

In the last 6 months or so I have read probably a hundred postings re: "how to treat rim joists". It's important to me since my 1700 SF basement has about 160 LF of rim joist (all except the daylight side in my 7 year old home). I have not seen my specific problem discussed.

Perhaps the climate here (40 miles north of Atlanta) is milder than most. Regardless, in this region, full basements are common, water infiltration through the basement walls seems rare, and every rim joist I have seen has fiberglass insulation, same as walls. My observations are limited and anecdotal, of course.

Problem: In three specific rim joist "bays" (the 14.5" space between floor joists) I found wet insulation and soaked particleboard and rim joist behind the fiberglass as I systematically removed it to seal air gaps. The source of the moisture was obviously rain infiltration due to poor flashing and caulking, and I had a roofer out last week to hopefully correct the problems.

Question: How would this have been discovered or repaired if sprayed on foam or even glued in XPS had been used? If I apply foam now, how can I check to insure the problem is corrected? The exterior siding at these locations is brick masonry, so I'm not anxious to remove it. If the builder had used sprayed on foam, I probably would not have discovered the leaks.

I'm leaving these areas open as I work on other parts of the basement, but will eventually have to bite the bullet.

Comments or reasurance please.

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