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Insulation

First, check the insulation in your attic, ceilings, exterior and basement walls, floors, and crawl spaces to see if it meets the levels recommended for your area. Insulation is measured in R-values—the higher the R-value, the better your walls and roof will resist the transfer of heat. DOE recommends ranges of R-values based on local heating and cooling costs and climate conditions in different areas of the nation. The map and chart below show the DOE recommendations for your area. State and local code minimum insulation requirements may be less than the DOE recommendations, which are based on cost effectiveness. For more customized insulation recommendations, check out the Zip Code Insulation Calculator. This tool provides insulation levels for your new or existing home based on your zip code and other basic information about your home. Although insulation can be made from a variety of materials, it usually comes in four types; each type has different characteristics.

Rolls and batts—or blankets—are flexible products made from mineral fibers, such as fiberglass and rock wool.

They are available in widths suited to standard spacings of wall studs and attic or floor joists: 2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products.

Loose-fill insulation—usually made of fiberglass, rock wool, or cellulose in the form of loose fibers or fiber pellets, it should be blown into spaces using special pneumatic equipment. The blown-in material conforms readily to building cavities and attics. Therefore, loose-fill insulation is well suited for places where it is difficult to install other types of insulation.

Rigid foam insulation—foam insulation typically is more expensive than fiber insulation. But it's very effective in buildings with space limitations and where higher R-values are needed. Foam insulation R-values range from R-4 to R-6.5 per inch of thickness, which is up to 2 times greater than most other insulating materials of the same thickness.

Foam-in-place insulation—this type can be blown into walls and reduces air leakage, if blown into cracks, such as around window and door frames.

Insulation Tips

Adding insulation to the attic is relatively easy and very cost effective. To find out if you have enough attic insulation, measure the thickness of the insulation. If it is less than R-30 (11 inches of fiber glass or rock wool or 8 inches of cellulose), you could probably benefit by adding more. Most U.S. homes should have between R-30 and R-60 insulation in the attic. Don't forget the attic trap or access door.

If your attic has enough insulation and your home still feels drafty and cold in the winter or too warm in the summer, chances are you need to add insulation to the exterior walls as well. This is a more expensive measure that usually requires a contractor, but it may be worth the cost if you live in a very hot or cold climate. If you replace the exterior siding on your home, you should consider adding insulation at the same time.

You may also need to add insulation to your crawl space or basement. Check with a professional contractor.

New Construction

For new homes in most climates, you will save money and energy if you install a combination of cavity insulation and insulative sheathing. Cavity insulation can be installed at levels up to R-15 in a 2 in. x 4 in. wall and up to R-21 in a 2 in. x 6 in. wall. The insulative sheathing, used in addition to this cavity insulation, helps to reduce the energy that would otherwise be lost through the wood frame. The table below shows the recommended combinations. For example, in Zone 5, you could use either a 2x4 wall with R-13 or a 2x6 wall with R-21. For either of those two walls, you should also use an inch of insulative sheathing that has an R-value of R-5 or R-6.

Today, new products are on the market that provide both insulation and structural support and should be considered for new home construction or additions. Structural insulated panels, known as SIPs, and masonry products like insulating concrete forms are among these. Some homebuilders are even using an old technique borrowed from the pioneers: building walls using straw bales. Check online at www.energysavers.gov for more information on structural insulation.

Radiant barriers (in hot climates), reflective insulation, and foundation insulation should all be considered for new home construction. Check with your contractor for more information about these options.

U.S. map showing recommended insulation levels for the home based on climate regions and heating type. For specific recommendations for your home, go to http://www.ornl.gov/~roofs/Zip/ZipHome.html or contact Energy Savers webmaster (http://www.eere.energy.gov/consumer/tips/webmaster.html) for more information.

All of Alaska in Zone 7 except for the following boroughs in Zone 8:

  • Bethel
  • Northwest Arctic
  • Dellingham
  • Southeast Fairbanks
  • Fairbanks N. Star
  • Wade Hampton
  • Nome
  • Yukon-Koyukuk
  • North Slope

Zone 1 includes

  • Hawaii
  • Guam
  • Puerto Rico
  • Virgin Islands

How Much Insulation Does My Home Need?
For insulation recommendations tailored to your home, visit the DOE Zip Code Insulation Calculator at www.ornl.gov/~roofs/zip/ziphome.html.

*These recommendations are cost-effective levels of insulation based on the best available information on local fuel and materials costs and weather conditions. Consequently, the levels may differ from current local building codes.

Chart showing recommended insulation levels for the home based on climate regions and heating type. For specific recommendations for your home, go to http://www.ornl.gov/~roofs/Zip/ZipHome.html or contact Energy Savers webmaster (http://www.eere.energy.gov/consumer/tips/webmaster.html) for more information.
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Content Last Updated: 1/21/2009