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Vapor Barrier in Crawlspace with thin layer of concrete

michaeldrehl | Posted in General Questions on

I am in Northern NJ. I have an old crawlspace with about 1/2 in of concrete. (The floor beneath the concrete is soil.) I would like to install a 6 mil vapor barrier. Below is the link to the polyethylene vapor barrier I was thinking of using. I was going to use the butyl tape to seal it to the foundation walls. 

But I came across reading online that I shouldn’t use vapor impermeable material. 
Avoid impermeable vapor barriers like glass, sheet metal, polyethylene sheets, or rubber membrane where semi-permeable or permeable vapor barrier materials will work.  Construction methods that allow interior wall materials to dry out are better than methods that prevent any moisture from entering.

Is this correct so any mold/mildew don’t form?

Ace Plastic Sheeting 6 mil X 20 ft. W X 25 ft. L Polyethylene Clear – Ace Hardware

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  1. plumb_bob | | #1

    You certainly do want a vapour impermeable membrane for this application, that is actually its purpose, to keep out water vapour (and soil gasses such as radon). You want it well sealed to the foundation walls to form a part of your continuous air barrier.

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