I live in the Phoenix, AZ area which can get very hot in the summer.

I currently have fiberglass rolled insulation in the attic (about a 21 rating).

What would be the optimal amount of insulation and what type of insulation should I add to the attic?

Also the garage and the patio areas are not insulated at all but are covered by the same attic. Should they be insulated too?

Thanks

Boris