Joe writes from Athens, Ontario: "I want to insulate my cement floor in the basement to be used as a rec room/entertaining room/family room. The walls are already completed. I'm planning on laying sleepers on the cement and using either batts or rigid insulation? Which will give me the most R-value and what is recommended? I do not have a water problem in the basement, so moisture is not a problem. Is a vapour barrier also recommended?”

Answer: Unless there is a vapor retarder and/or rigid foam insulation under the slab, a concrete floor will always bring in moisture from the ground and will always feel cold. Here are some comments:

1.  It is better to install a vapor retarder before the sleepers.

2.  A Celfort® 200 extruded polystyrene, 2 inches thick will provide R-10 and keep the floors comfortable. In comparison, it takes 3.5" thick fiberglass insulation to achieve R-12.

3.  I suggest installing Celfort 200 extruded polystyrene over the vapor retarder and then build the sub floor over it.