Whether using loose fill or batts put the vapor barrier closest to the warm side of your installation where hot moist air would get in facing the house s interior in cold climates beneath floor insulation and the attic s interior in hot climates on top of floor insulation.
Hot attic insulation.
The two basic types of attic insulation are rolled insulation and blown in attic insulation.
For hot climates where most of the radiant heat hitting the attic comes from sunlight radiant barriers should be draped from the attic ceiling or installed between the roof beams.
Within the attic insulation is a must.
A thick insulation between 14 to 18 inches will help reduce heat from entering your home.
A good way to gage if more insulation is necessary is to look in your attic for ceiling rafters.
If you can see the ceiling rafters you need more insulation.
Focus a lot of energy pun intended on the underside of the roof to keep the heat out of the attic and not just the floor of the attic.
The most important factor to consider in a warmer climate is the addition of a radiant barrier to whichever type of insulation you select.
In cold climates the best radiant barriers are installed on the floor of the attic so that they can redirect radiant heat from the home back into your living spaces.
You can use products like radiant barrier on the underside of the roof spray foam or even good old fashioned batts of rock wool denim or fiberglass.
Some regions don t require a vapor barrier.
Building codes vary among the thousands of jurisdictions but a typical requirement in hot climates is r 38.