bigone5500
Well-Known Member
I have some 1/2" insulation board which has an R value of 3. If I use 3 layers of this material it should have an R value of 9 right? I have tried to find information on this and what I have found really doesn't tell me for sure. I may have to go with some roll insulation but want to use this stuff I have already. If the R value is only 9 then I will probably not use it. I have been rebuilding a storage shed and have insulated the walls with R13 fiberglass rolls. It may be best to continue to use that in the ceiling.