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Community and Q&A

Basement walls – spray foam over vapor barrier

johnchard | Posted in General Questions on

Hi and pardon upfront for the naive question…

House is a 1916 farmhouse style in zipcode 06820. The foundation is rubble stone.

The basement is for the most part dry but in the in a small annex where the oil tank is housed (soon to be removed – thanks to the GBA guidance we have installed mini-splits) we have had an extensive amount of water coming through the bottom of the wall and floor after intense weather. We have also noticed some moisture at other floor wall intersections.

Due to the gardens and porch, we cant install exterior drainage / waterproofing. We had planned to insulate the basement with 2 or 3 inches of closed cell spray foam. With the increasing weather volatility, I feel I have no choice but to install an interior french drain and sump pump. A well known basement repair vendor here in CT suggested in the quote – the drain, sump and a polyethylene vapor barrier (product they call CleanSpace) on the rubble wall.

Basic question is – can I do both? Can the spray foam go over the “Cleanspace” vapor barrier that runs from the rim joist down to the drain? I know MH’s recommendation in one of his fantastic posts was for a dimple mate. As man lacking DIY skills as well as time, can this solution work?

Guidance appreciated! 



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  1. Expert Member
    NICK KEENAN | | #1

    I'm very interested in the responses as I own a similar vintage house in nearby RI with all the same issues. I've been thinking about dimple mat for the bottom 30" of the cellar wall, then spray foam up the wall and into the joist bays.

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