Energy-Saving Tips for Insulating

Experts estimate that 40 million single-family homes in the United States need more insulation. Could yours be one of them?

The Value of R-Value

R-value is a number that measures insulation's resistance to the passage of heat. The higher the R-value, the more effective the insulation.

Start at the Top
Your attic floor, or the ceiling of your top story, is your building's primary candidate for insulation. You could save up to 30 percent of your energy costs by better insulating your attic or top floor.

Insulate on all Sides

You could save as much as 20 percent of your heating and cooling costs by insulating your exterior walls.

Energy Loss Underfoot

You can save about 8 percent of your energy costs by insulating the floor over any unheated spaces such as crawl spaces, basements, and garages.

Blanket and Batt Insulation

Blankets (continuous rolls) and batts (pre-cut sections) of rock wool or glass fiber are used to insulate attics, walls, and rafters as well as underneath floors. They work best where there's a standard space between joists or rafters and few obstructions. Both types are available with or without vapor barrier backing.

Loose-Fill and Blown-In Insulation

It's easy to insulate unfinished attic floors with poured-in glass fiber, rock wool, cellulose, vermiculite, or perlite insulation. Check to make sure your insulation meets federal specifications. Blown-in insulation also is good for filling the nooks and crannies in finished frame walls.

Rigid Board Insulation

Board insulation made of polystyrene, urethane, or fiberglass works best for outside wall insulation. Some kinds require extra fire safety precautions and should be installed only by a contractor.

Insulation Precautions

When buying insulation, ask about its resistance to fire and moisture. Don't seal off vents, don't insulate over recessed lighting fixtures, and keep the material at least three inches from any heat-producing fixtures.

Use Vapor Barriers and Attic Ventilation Against Condensation

Condensation can be a heating season problem for your energy savings and your home or business. Vapor barriers, usually made of plastic or aluminum foil, should face the heated part of the building. But don't put a vapor barrier over existing insulation. For your attic, calculate one square foot of vent area for every 300 square feet of attic. A variety of attic ventilators are available, including roof louvers, turbine wheel vents, gable-end louvers, ridge vents, and soffit vents.