Greg writes from Minot, North Dakota: "I'm looking at building a new wall up against my concrete basement wall. I'm wondering if you think its a good idea to mix foam and fiberglass insulation together to achieve a higher r value?

My plan is to put foamular 150 1 inch thick foam on the concrete wall, then build my wood frame and fill it with Owens Corning R15 insulation fast batt. Would this work? Or should I not use the foamular 150 and just build my wall using the fiberglass insulation and poly moisture barrier?

I have no moisture problems that I can see in my basement. The basement walls are painted. We recently had 15 inches of rain in my neighborhood over a month's time, and never got any water leaks or moisture deposits on the walls. I have a sump pump in my basement because I live in a high water table area; it ran all the time but I never had any problems with water."

Answer: It is acceptable to use one inch thick FOAMULAR® 150 insulation in conjunction with FIBERGLAS® insulation. However, we recommend that the FOAMULAR be placed on the inside face of the framing members, not behind the FIBERGLAS insulation. We also recommend that the FIBERGLAS insulation used be unfaced. This system will increase the R-value of the wall by 5.