Originally Posted by Alan
Don't most single story houses have insulation above the sheetrock that is hanging from the rafters?
Yes, sort of. You're confusing terms here. Your rafters
are the sloped members that frame the pitch of the roof. Your ceiling joists
are the horizontal members that frame the ceiling, and the sheetrock is attached to them. Rafters are not typically insulated unless you have a pitched ceiling that follows the pitch of the roof. Ceiling joists are always insulated.
Around here, most ceilings are insulated with blown-in cellulose. It is inexpensive and easily done by a DIY-er. The thickness depends on climate and local requirements. I wouldn't suggest insulating your rafters in too many circumstances.