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Existing basement slab vapor barrier questions

John Ranson | Posted in General Questions on

I’m buying a house with an existing basement slab. It’s mostly in good shape with a few rough patches. I have no idea how old it is, or whether it was installed with a good vapor barrier. I’ve got two questions:

What’s the best test for a homeowner to see if the slab has a good vapor barrier?

Is there a durable, low height, and preferably inexpensive way to add a vapor barrier to the slab top? I’m not looking to finish the basement. I just want to reduce the moisture. I do want something that’s will robustly handle the current roughness of the slab and any future concrete cracking.

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Replies

  1. Expert Member
    DCContrarian | | #1

    A quick test is to put something impervious over a section of floor, then come back later and see if it's wet. Condensation indicates a lack of vapor barrier. Lack of condensation doesn't indicate anything though.

    You can paint the floor with a vapor barrier paint.

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