Southern California is considered Zone 3 by the Department of Energy. The recommended insulation values
for Zone 3 are:
- Attic R30 to R60
- Cathedral Ceiling R22 to R38
- Cavity R13 to R15
- Floor R25
Kraft faced insulation or poly vapor barrier is required on the warm side of exterior walls.
Insulation should be neatly fit into place with minimum amount of compression.
If water lines and the ducts of your heating or air-conditioning system run through unheated or uncooled
spaces, such as attic or crawl spaces, then the water lines and the ducts should be insulated. Wrap the
ducts with duct wrap insulation of R6 with a vapor retarder facing on the outer side. All joints where sections
of insulation meet should have overlapped facings and be tightly sealed with fiber glass tape while avoiding
compressing the insulation.
Air sealing is important, not only because drafts are uncomfortable, but also because air leaks carry both
moisture and energy, usually in the direction you don't want. Air barriers/vapor diffusion retarders are
generally placed around the perimeter of the building just under the exterior finish. The key to making them
work effectively is to permanently and carefully seal all of the seams and penetrations, including around
windows, doors, electrical outlets, plumbing stacks, and vent fans. Caulk forms a flexible seal for cracks,
gaps, or joints less than 1-quarter-inch wide. It is a good practice to run a bead of caulk, both internally and
externally between the concrete slab and the sill plate.
Finally, weatherstripping should be used to seal air leaks around movable joints, such as windows or doors.
For acoustical insulation see Acoustical Insulation.