How to Build and Insulate Basement Walls
LESLIE: Terry in Illinois, you’ve got The Money Pit. How can we help you today?
TERRY: Yes. I’m talking about some Styrofoam insulation in a basement. And my concern is a vapor barrier. Is it the proper way to put the plastic up against your foundation wall and then go with the Styrofoam? Or is that the correct way or wrong way or does it make any difference?
TOM: Well, with Styrofoam insulation, since it’s not an organic material, you can put that right up against the foundation wall. You don’t have to put a vapor barrier over it first.
So, are you going to frame-in the walls?
TERRY: Yes. The walls are going to be all framed in and 2x2s and 2-inch Styrofoam will be inside 16-inch centers.
TOM: So you’re going to attach the 2x2s to the concrete wall and then you’re going to put the Styrofoam in between that.
TOM: I’ve got to tell you that personally, I don’t like to do that. I like to leave space between the wall – the block wall – and the framed wall or the drywall because I think it allows it to dry out better if it gets damp down there. So I personally prefer to frame a wall inside the basement walls and not attach it to the outside.
If you are going to attach it – or frankly, even if you’re not – you also should be aware that drywall is really a bad choice for a basement area. I would use a fiberglass-faced wallboard. There’s one called DensArmor – D-e-n-s-Armor. It’s made by Georgia Pacific, pretty readily available. More expensive than paper drywall but because of the fiberglass face, it can’t possibly grow mold and that’s definitely something to be concerned about in the basement.
TERRY: Alright. Thank you.
TOM: You’re welcome. Good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.