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XPS on both sides of foundation wall

user-901114 | Posted in General Questions on

I have 2 inches of XPS on the outside of my basement walls, both above and below grade. I was considering putting 2 inches on the inside as well, followed by a framed wall with R-23 Roxul and sheetrock.

Are there any risks with this assembly?

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  1. GBA Editor
    Martin Holladay | | #1

    Q. "Are there any risks with this assembly?"

    A. You should be fine, as long as the basement wall isn't damp, and as long as there are no problems with water entry.

    Do your best to install the interior rigid foam in an airtight manner, to prevent any interior air from contacting the concrete wall.

  2. user-901114 | | #2

    Thanks Martin. The wall is damp at the bottom. I've dug up around the foundation and laid drains, coated the wall with tar and put 2in of xps and it's still damp. Which I put sheet of poly there too. What I don't know is if it's condensation or not... So I'm going to try putting tin foil on it this weekend. Could exterior insulation make my foundation wall colder on the inside? There is no heat in the house yet.

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