crawl space condensation

[Jim Robinson]

I have seen this several times in the past few years. The rim board along the north side is getting saturated with moisture condensing between the insulation vapor barrier and the wood.

The area will dry out pretty quickly once the insulation is removed. However, is there another method of insulating this area that will prevent the condensation from forming? Possibly closed cell foam, or maybe an additional vapor barrier along the bottom of the joists at the perimeter? Has anyone had any experience in preventing this situation from occurring short of not insulating the last joist space?

[Scott Patterson]

I have seen this several times in the past few years. The rim board along the north side is getting saturated with moisture condensing between the insulation vapor barrier and the wood.

The area will dry out pretty quickly once the insulation is removed. However, is there another method of insulating this area that will prevent the condensation from forming? Possibly closed cell foam, or maybe an additional vapor barrier along the bottom of the joists at the perimeter? Has anyone had any experience in preventing this situation from occurring short of not insulating the last joist space?

Not knowing if you are in a heating or cooling climate, it is really hard to diagnose. In most of the South, homes do better with no insulation of the subfloor. In my location in TN, we have enough of a cooling climate and lower humidity that subfloor insulation is OK.

I would be looking at air leakage, either from air ducts or the interior of the home is communicating with the crawlspace. Are the CMU blocks open at the top?

[brian schmitt]

is there any underfloor venting,plastic on the ground?

[Tim Netzley]

I agree with Brian. The IRC requires proper venting of crawl spaces and vapor barriers dependent upon locale.