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I'm finishing a basement and have 8 foot and half concrete walls that I will be placing a stud wall in front of. I've scoured the net only to find a large number of opinions. My basement wall has an exterior guard done by superseal which provides this dimpled plastics that goes around the entire basement foundation and slab. My basement has been ultra dry, the saran wrap test yielded no moisture. Books stored down there look new.

So my question is, which method should I use for my foundation walls?

A) based on the Mike Holmes approach I should be using 2" XPS rigid foam board with tuck tape and then spray sealed for the vapor barrier followed by stud wall with no plastic vapor barrier. Bottom plate is treated.

B) gap between concrete wall and stud wall, stud wall with treated bottom plate, insulated with Roxul mineral rock insulation and then plastic vapor barrier.

Going the XPS rigid way is quite a lot more and I'm not sure it would provide more value.

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The 'Mike Holmes' way is also the Building Science Corporation's recommendation--though they don't recommend any formal vapor barrier--just XPS and tape. The idea is that XPS is a vapor retarder, but can ultimately dry one way or the other if it ever has to.

That said, if you are absolutely 100% sure your basement will be forever dry, it probably doesn't matter what method you go for. You do have a strong advantage by having exterior waterproofing.

Regardless, I wouldn't use wood in the basement (treated or otherwise) and instead go with metal studs. They're just so much easier to work with. I outline my other reasons for that here: https://diy.stackexchange.com/a/8644/1209

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  • Thanks so much for your response. I read this article on that site for anyone that comes across this question: buildingscience.com/documents/bareports/… Well, pricing out the xps.. looks like I'll be adding another $1372.. :(
    – Dolph
    Commented Dec 8, 2014 at 18:18
  • @Dolph if you go that route, consider EPS as well. You need it a bit thicker for the same r-value, but can cost a lot less than the EPS, and essentially does the same thing.
    – DA01
    Commented Dec 8, 2014 at 18:24

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