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Exterior foam and dimpleboard installation below grade

user-7022518 | Posted in Green Building Techniques on

We are planning on using exterior foam insulation on our poured concrete basement walls and a dimpleboard. We know that the dimpleboard can be placed under or over the foam. If the dimpleboard is placed against the concrete wall under the foam, how is the foam held in place? I am assuming that penetrating the dimpleboard with fasteners is going to be a problem.


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  1. GBA Editor
    Martin Holladay | | #1

    The dimple mat doesn't have to be waterproof. Penetrations won't hurt its performance. It works by providing clear air channels from the top of the wall down to the footing drain. As long as liquid water can flow downward, the dimple mat works.

    For more information, see this article: "Using a Dimple Mat to Keep a Basement Wall Dry."

  2. user-7022518 | | #2

    Thank you Martin! Sometimes these detailing instructions sound like recipes--reminds me of baking where chemistry, physics, precision, and artistry collide... Lisa

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