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Should I reseal the basement walls prior to installing rigid foam?

user-4627913 | Posted in General Questions on

Hi everyone, I’m planning on installing 2″ of Dow Thermax rigid foam on the interior walls of my basement and the wall that is against living space in the garage. I got inspired by Marc Rosenbaums article on his installation. The walls were previously sealed by another homeowner. Should I clean them up and apply another coat of waterproofer or can I install the foam over the walls the way they are? Thanks in advance for any info.

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  1. GBA Editor
    Martin Holladay | | #1

    You can't insulate a basement wall on the interior unless you are sure that the basement has no water entry problems. If there is a history of water entry, or there are signs of dampness, this problem has to be addressed before insulation work begins.

    Assuming that your walls are dry, and are likely to stay dry year 'round, you can go ahead and install insulation without applying a sealer.

    For more information on these issues, see:

    How to Insulate a Basement Wall

    Fixing a Wet Basement

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