Basement walls

I will be re-finishing the basement, and have a 30 foot long exterior wall, mostly below grade. Space is at a premium, and I was wanting to apply 1 inch foam directly to the concrete, and put up sheetrock with adhesive and a few well placed tapcons, avoiding the 3/4 inch furring strips. Water on the exterior is 100% managed, and there is a black coating on the exterior wall below grade, presumably from the build date in the 70's. Any moisture issues with the foam directly on the concrete? The humidity here in Denver is quite low. Is any treatment from the inside advisable? And if strips have to be used, do they go on first? Thanks for your help.

 

Is this going to be a finished space? How do you plan on running your code required electrical outlets?
4"x4" steel boxes are 1 1/2" deep + 1/2" mid ring for the rock.

 

Thanks Ironhand. More info: The bottom 3 feet approx of the wall will be a stud wall, creating a ledge of a foot or less in width just below pool table height. The ledge will be capped with granite or countertop material. The electrical outlets will be at the 12 or 18 inch height in the stud wall. There are no switches on that wall. I figured whatever space was in and behind the studs would be filled with batts, and hoping for the foam to be tongue and groove 1 inch, unbroken from floor to ceiling. The ceilings are about 7 feet. Thanks plgamble

 

I'd rethink your idea of no furring strips, regardless of the space restrictions. Any Tapcons will pull right through the foam when your adhesive decides to let go, meaning you will have a big mess on your hands. Penny-wise, pound-foolish.

I personally wouldn't use anything less than 2 x 4s in the flat orientation, if only to provide for some decent nailing surfaces for hanging pictures on that 30-foot wall. Bare paint will get ugly in a hurry.

 

Ok Bridgeman, Thanks. What is the ideal sequence of furring strips, and 1 inch foam insulation? Should there be any treatment to the concrete wall, or a vapor barrier in the mix? The inspector here recently saw 2 inch foam on all my (conditioned) crawlspace walls, and was happy. Thanks for your help! plg

 

If it were mine, the walls would get a coat of DryLok, then anchored flat 2 x 4s @ 24" centers, then 1-1/2" of foam between them, then sheetrock, texture, primer and paint. No plastic vapor barrier--you did say it's bone dry, yes? The DryLok is just insurance for when you might have an abnormal weather incident, or one of the bratty neighbor kids turns on a hose spigot while you're gone for the weekend, etc.

 

OK, Thanks, Why only the 1/2 inch of foam? and only between the 2x4's? is there just no need for a more complete thermal break, below grade? I have 2 inch foam, double deep, for all the rim joist, and the top 1 foot or so is above grade. Thanks for sticking with me, BridgeMan.

 

I think I said 1-1/2", which is 1.5". The same thickness as the flat 2 x 4 furring studs. You had earlier mentioned using 1" of foam, which would leave a 1/2" (0.5") air gap between it and the back of your rock, which I think is a mistake. If you really want to go overboard, build a stud wall with 3-1/2" (3.5") of foam between the studs.

 

FWIW, I did Dry Lok, then 3/4 furring strips (ie. 1x3's) tapcon'd to the block, with 3/4 foam between them (glued to the block), then drywall over that. Existing outlets were already dug into the block.

I'm happy with it, and didn't see any reason to move up to sideways 2x4s.