Tim writes from Hainesport, New Jersey: "I'm trying to determine the proper way to install a vapor barrier. I've just recently begun refinishing my basement; even though I've never experienced any water or moisture problems I chose to seal the walls and floor with DryLok just as a precaution. Now I plan to install 2x furring strips along the walls and put up 1 1/2" extruded foam insulation, tape all seams and caulk all joints. Then I will frame the walls with 2 x 4's and insulate with fiberglass batts.

My confusion comes with the installation of the vapor barrier. Some things I have read state to install the vapor barrier closest to the warmest side of the room directly under the drywall. Others say to install the plastic along the concrete walls. Which is correct? Wouldn't the installation of the DryLok and rigid foam essentially be a vapor barrier? And, should I use fiberglass insulation that has a paper facing, or not, in conjunction with a plastic vapor barrier? Sorry this question is so long but I want to make sure I do the right thing."

Answer: We do not recommend a plastic vapor retarder anywhere in the basement. In your application there is no need to install an additional vapor retarder over the foam. You can install either unfaced or Kraft-faced insulation in front of the foam. If you choose Kraft-faced insulation, the vapor retarder should face the inside of the wall, which will be the warm side in winter.