Richard writes from Dowagiac, Michigan: "I'm constructing a new home and I'm considering spray foam (closed cell) in the exterior walls with fiberglass batts covering the foam. Will the spray foam act as a vapor barrier creating a condensation problem between the foam and the fiberglass. I have been told that will happen if the spray foam is too thin. If so, how thick do I need to make the spray foam?"

Answer: The spray foam you are asking about is not made by Owens Corning. You should ask the spray foam manufacturer to answer your question. If the spray foam is a vapor retarder, then you will want to use unfaced (no paper) fiberglass insulation in the application you describe.