When insulating don’t forget to insulate the attic access door, walls between living spaces and unheated garages or storage areas, foundation walls above ground level, foundation walls in heated basements, and slab floors built directly on the ground.

Other Places for Added Insulation
Don’t overlook another area in your home where energy can be saved—the ductwork of the heating and air-conditioning system. If water lines and the ducts of your heating or air-conditioning system run through unheated or uncooled spaces in your home (such as attic or crawl spaces), the water lines and ducts should be insulated.

First, check the ductwork for air leaks. Repair leaking joints first with mechanical fasteners, then seal remaining leaks with water-soluble mastic and embedded fiber glass mesh. (Never use gray cloth duct tape because it degrades, cracks, and loses its bond with age.)

If a joint needs to be accessible for future maintenance, use pressure or heat-sensitive aluminum foil tape. Then wrap the ducts with duct wrap R-6 insulation with a vapor retarder (or vapor barrier) facing out.

Sealing Air and Moisture Leaks
The air leakage in a typical U.S. home is equal to leaving a window wide open -- and a constant drain of energy and money. To stop these air leaks, all doors and windows should be weather-stripped and all seams, cracks, and openings to the outside should be caulked or sealed.

Moisture control is also important to maintaining an energy-efficient home. If humid air leaks into cool spaces, moisture can condense and cause damage. In addition, moist insulation has a lower R-value, so moisture problems will lower your home’s energy efficiency.

One way to control moisture is to seal air leaks around electrical outlets, switches and other penetrations through the building envelope for plumbing, wiring, ventilating, heating and cooling, and attic access.

Don’t forget to check the hot water pipe that may pass from an unheated basement into your kitchen. Hardware stores sell a variety of grouts and sealants to plug the gaps around pipes such as these, as well as gaskets to install behind electrical outlets and switches.

Vapor barriers or retarders are another way to control moisture. Vapor barriers include polyethylene sheets, low-perm-rated paints, laminated asphalt-covered building paper, vinyl wall coverings, and foil-type wallpapers.

Vapor barriers should always be placed on the warm-in-winter side of the insulation. Do not install a vapor barrier over existing insulation.