Working from scratch with a bare wall. What do I do? 3 hardware stores have told me 3 different things. We have very cold winters here. Looking for cheapest and highest R value. contractor next door says 2 layers ridged R5, overlapping and taped...2x4s...then gypsum board. He says I don't need a vapor barrier.

  • Potential duplicate: diy.stackexchange.com/questions/8636/…
    – DA01
    Oct 2 '12 at 3:24
  • Taped layers of rigid foam is a vapor barrier, it's just that you don't need an additional vapor barrier.
    – Matthew
    Oct 2 '12 at 15:21
  • 1
    @MatthewPK no, it's a vapor retarder--not barrier.
    – DA01
    Oct 2 '12 at 18:12
  • I believe there is a minimum thickness at which it is considered a barrier. I don't have a source for this at the moment, but I think 1.5" is the magic number.
    – Steven
    Oct 3 '12 at 2:04

Best place to go for this sort of information is buildingscience.com. This set of documents on basements will have lots of useful guidance.


Space your framing half inch off the wall then closed cell spray foam. It depends on how much you want to spend and how much space you want to give up.


Read this answer I provided here (this question is likely a duplicate of it):

Should I use steel or wood studs for basement exterior walls?

Broadly speaking, there are two ways to answer this:

  • do it the way code states
  • research and do it the way you want to do it, potentially having to convince the code folks it's the better way.

I chose the latter after doing a lot of research (see above link) that states that vapor barriers are probably a bad thing in a basement. Code dictated that there be a barrier, and as such I had to spend a chunk of time doing a lot of documentation and providing citations to other research to convince them otherwise (I was able to finally convince them).

To summarize, I generally agree with your neighbor, and would suggest a) using metal studs instead of wood (mold can't grow on metal + it's really easy to work with) and b) upgrading the wall board to a paperless product such as densarmor (which uses a fiberglass surface instead of paper).

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