I am looking to retrofit a home built in 1967 in Tampa, Florida. The current blown-in attic insulation is original and about 3 inches. Would a reflective insulation alone attached to the bottom of the top cord of the roof truss be a good option?
In the hot climate you have in the Tampa area, a radiant barrier would be an excellent option. I would suggest that this would be the first thing you should do to upgrade the thermal performance of the attic.