Q: I have 7 inches of insulation in the attic running between each rafter. I’d like to add another 6-7 inches. Would it make a difference if I placed the new insulation perpendicular to the already existing insulation rather than lay it the same way as the present insulation is now? Would that be better as far as keeping the heat from escaping from the below living area? –Paul R.
A: Actually, it does make a difference. Initially, your insulation batts were installed between the ceiling joists, which is normal. However, that means that the wood joists themselves are not covered with insulation. Since wood has a lower R-value than fiberglass insulation, there’s actually a long cold spot running along each one of those joists, relative to the insulation alongside it. (It’s one of the reasons why blown-in attic insulation creates a more uniform insulation layer).