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Basement insulation

Hi, m,y name is Chris, and I am having a house built. I live in a mixed-humid climate - southern Illinois. My basement will be mostly unfinished. I say mostly because we decided to finish a bathroom. Two sides of the bathroom are the basement concrete wall.

I told the contractor to install rigid foam insulation along the concrete walls, and frame the wood studs in front of it,. I then planned to have more insulation installed (between the studs) prior to drywall.

What he did was attach the studs sideways (3.5-inch side)directly to the concrete wall, and then put 1.5-inch rigid foam in-between them. My question is, what should I do? Should I rip it all out? Can I do another standard wall frame out over this and put insulation = rigid foam or spray foam,in that wall and then drywayll, or can I leave it as is and put drywall over. Any advice appreciated!

Asked by Chris Johnston
Posted Sep 11, 2010 12:04 AM ET
Edited Sep 11, 2010 7:55 AM ET


2 Answers

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The studs in direct contact with the concrete are likely a problem. Are the concrete walls below grade? I'm wondering if his approach has anything to do with the location of the toilet drain in the floor. If there's a typical 12" rough-in along one of the concrete walls then he may be trying to keep the finish at 10", because there are toilets out there that will still fit. Just a wild guess.... I could be completely wrong.

Answered by David Meiland
Posted Sep 11, 2010 12:45 AM ET


What to do depends on whether (1) the studs are pressure-treated, and (2) whether a thicker wall creates any problem. If they are PT, they can stay, as long as the added thickness doesn't cause any problems. If they aren't PT, they have to be removed.

If you keep them, put at least one more layer of continuous rigid foam over the studs before building a proper 2x4 wall.

If you remove them, install continuous rigid foam along the wall, the way it should have been done from the start.

Answered by Martin Holladay, GBA Advisor
Posted Sep 11, 2010 6:40 AM ET

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