We are renovating our basement which was finished with panelling. We removed the panelling and found that the insulation used was 1" styofoam. Would this be adequate insulation for the basement if we finish the basement with drywall? Would it require a vapour barrier? If not could we install bat insullation over the styrofoam then cover with a vapour barrier or would it be preferable to remove the styrofoam prior to installing the bat?
Thanks
Rick
Answer:
Hi Rick,
With today's energy prices it's difficult to justify just a 1-inch layer of foam for basement insulation. That's only R-5. A normal 2x6 wall insulated with fiberglass comes in a R-20.
If this were my basement, I'd leave the old foam in place and cover it with additional layers of a product called Wallmate. This is an extruded polystyrene foam made especially for use in situations like yours. It's made by Dow and includes grooves to accept wooden strips. Theses hold the foam to the wall when secured with screws or nails, then also form nailing surfaces for drywall. I have nothing to gain by this recommendation. It's simply the best way to go in your situation.
