I want to know if I it is worth my money to insulate my roof. Here is what I have, the floor of my attic is filled with blown celulose insulation and covered with OSB. However, my roof, which is constructed with 2x4s, is not insulated. Both ends of the attic are gabled and have exhaust fans that turn on when the temprerature raises above 75 degrees. During the summer, (I live in Virginia) the attic reaches the 100 degree mark and beyond.
I would like to know if it is worth my money to insulate the roof so that the heat that is absorbed by the asphalt shingles doesn't transfer through and into the attic, thus heating the attic which in turn transfers the heat through the attic floor/second storey celing and into my house. If you think I should insulate the roof, what would be my best return on value? Since the roof is 2x4 construction, I believe that I could only fit R-9 fiberglass insulation. Would I be better off using the sprayed in expanding foam insulation? Or, is there another angle I haven't considered?