Insulation, Radiant and Vapor Barriers - Insulating exterior wall in shower

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mattandsarah
10-23-05, 08:33 AM
We are in the process of tearing out a shower due to moldy greenboard. We have the cement board and 6mil vapor barrier, but are wondering about the insulation. The wall is 2x4, with some sort of foam insulation on the exterior side of the studs. We wanted to get R15 fiberglass insulation, but none of the big box stores carry it in Madison, WI.

What would you recommend for insulating this wall? Will R-13 be sufficient, or can I use layers of the pink extruded foam (with an r value of 5.0 per inch)? Or is there another source I haven't considered for finding R15 insulation?

Thanks in advance!

Concretemasonry
10-23-05, 10:16 AM
You may have the correct amount of insulation if you use the R13. You mentioned that you have some foam insulation on the outside of the studs and this could be added to the fiberglass to acheive the insulation level you are after. The type and thickness of the insulation would tell you. Only 1/2" of any decent foam would do it.

Most engineers recognize this. I don't know what the Republic of Wisconsin currently has for a energy/insulation code, but if it is one of the national standards you should be OK. A few years ago (ala DILHR), it would be anyone's guess.

Dick