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Rigid foam over textured concrete basement wall?

Andrew C | Posted in Energy Efficiency and Durability on

I think the standard advice at GBA about insulating basement walls is to put rigid foam flush against the basement wall, and then install some sort of fire barrier, e.g. drywall. The key is to prevent moist air from contacting the cold basement walls and then condensing.

In our area, many houses have poured basement walls that apparently used concrete form liners to give a fake brick texture to the walls. If one were to use standard sheets of rigid foam, there would be a 3D network of air channels behind the foam. If the rigid insulation seams are taped well, are there any issues here, or would you just proceed the same as you would if the walls were flat?

Note: I have no interest in spray foam, except perhaps canned foam for sealing where tape won’t work.

Thanks,

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Andrew,
    This is a judgment call. Closed-cell spray polyurethane foam would be the best solution, of course, although I understand why some people prefer to avoid spray foam. (When it comes to basement walls that are made of stone and mortar, or dry-laid stone, spray foam is to only acceptable interior insulation material.)

    If you want to use rigid foam on the type of wall you are describing, make sure that you use a very thick bead (or several very thick parallel beads) of caulk around the entire perimeter of the field of insulation.

  2. Michael D | | #2

    You might also consider Great Stuff adhesive instead of caulk
    http://www.homedepot.com/p/GREAT-STUFF-PRO-26-5-oz-Wall-and-Floor-Adhesive-343087/202892488

    It expands slightly and may fill the uneven spots isolating the channels to individual sheets. I used it in a basement and found it also to be much better on the pocket book than caulk adhesive. It takes a while to dry so we used 2x4 T's leaning against the panels to hold them to the walls for a few hours. For your application you may want to test several approaches before picking the final solution.

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