There are three types of radiant barriers on the market:
1. Spray on radiant barrier
2. Radiant barrier chips
3. Radiant barrier sheets
I still recommend avoiding #1 and #2 at all costs, even if you can get it for free! On the other hand, the radiant barrier sheets do work and are ideal for a southern Arizona climate and home style. With over 300 days of sun, radiant barriers will reflect the source of heat gain that insulation can’t stop, and that is radiant heat. They will keep the attic cooler in the summer, and, because most of southern Arizona’s homes are built with the ductwork in the attic, the AC units will not have to work as hard to offset the attic air heating up the ductwork.