My question is: I have two buildings, one is stick built 6" walls with R-13 in the walls,R-19 in the ceiling, which I am adding an additional R-19 to make an R-38 do to the fact that we are in Michigan. The building sits on a cement slab, the building is 20' x 20' and is heated with propane. The second building is the same size, same foundation,same insulation in the ceiling, but built out of 8" cement blocks, there is no siding on the outside and the inside was not built out with wood strips and insulated, the walls are just brick inside and outside. I have had contracters say the block is more efficent due to the air space in the block. What is the R-factor in that air space? What is R-factor in an 8"block? Which building will be more efficent to heat all winter?
Thank You,

JH