Basement Wall Question

Old 03-29-12, 09:34 AM
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Basement Wall Question


I'm beginning the planning for finishing my basement. My question is this:

There's a section of my basement that is separated from the main section by a concrete wall. It's kind of like the main rectangular basement foundation (poured) had a section added on, and a doorway cut into the side of the old section leading to the new one.

The new section is where I'm planning to put the first room. I'm going to either use rigid foam board insulation or spray foam for the exterior walls. I'm not sure about the walls between the two sections of basement though. Does that concrete need to be insulated all around? If not, does it at least need moisture barrier against it? It would seem to me that there needs to be something around it, as it's a continual wall, the rest of which is exterior. Couldn't cold/moisture work its way down the wall into my finished area?

Hopefully the explanation makes sense!

Old 03-29-12, 10:01 AM
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I assume the added room is part of the living space. If it is, there is no need to insulate/isolate the spaces since they are both a part of the conditioned space. The thermal inertia of the concrete will over-ride the effects of any insulation. Just make sure you have adequate cold air returns near the floor for comfort and benefits from the thermal mass in the summer if you have central AC.

Old 03-29-12, 10:05 AM
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As Dick said, don't insulate the internal walls in the basement. We had someone post last year who had done that and now the area was proving difficult for the homeowner to heat and cool properly.

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