Question on Finishing basement

Supplicate

Wasn't sure if this belonged in Remodels or Carpentry, so I'm dropping it here first

Anyhoo, a co-worker asked me to help him finish his basement and this has brought up a couple questions I have no answer for.

The plan:

We are planning on doing a solid foamboard shell on the walls and the floors (1" on the walls, 2" on floors if possible), with 3/4" plywood on the floor and 2x4 framing on the walls to facilitate the wiring for electrical and home theater.

The question:

When insulating the basement with the rigid foam board, can the floor be completed first with the stud wall being bolted down on top of that or should the stud wall be as close to the concrete as possible?

We are also planning on putting a layer of the Delta-FL vapor barrier down under all of this.

toddmanqa

I would do it thusly:

Delta-FL vapor barrier
foam
plywood
Tapcom bolts through plywood/foam into concrete
pressure treated 2x4 bottom plate
stud wall

Pressure-treated 2x4 is overkill, but you don't want some nit-picky building inspector telling you to rip out your walls cause you didn't use pressure treated wood.

The stud wall isn't holding anything up structurally, so it' doesn't have to be bolted to the concrete. Bolted to the plywood on the bottom and the 1st floor should be plenty strong enough.

Be sure to use tuck tape on the seams of the Delta-FL and on the seams of the foam.

Supplicate

Thanks for the reply. Going to use tuck tape for sure.

Only reason we were wondering about putting the wall on top of the foam/plywood structure is the concern that the foam might compress over time and cause cracks in the drywall at the top plate.

benjamincall

Most of the XPS foam out there (blue or pink) has a compressive strength of 25 psi. You can actually put 25 psi XPS foam under the footings to your house. If you want an extra degree of certainty that you won't have problems, both Dow and Owens Corning make 40, 60, and 100 psi foam.

Please refer to this article:

http://www.greenbuildingadvisor.com/...under-footings

Edit: Rise and shout, the cougars are out . . .