Is it overkill, well my R110 attic was worth every penny. In zone 5, I
had a yearly Ng bill of 460 for 1800sq a few years ago. Mine has settled
to R70 it is fiberglass bats. If you are zone 8 or less R 70 + is a
good idea. Standards are outdated, insulation is cheap compared to Oil.
I had a load calc done , 1800sq ft and only 50000 btu.