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What Are Good Insulation Values for My New Home?

by R. Lynne

New homebuyers want energy-efficient homes that are well-insulated to reduce heating and cooling costs. The Federal Trade Commission requires new home sellers to disclose the type, thickness and R-value of insulating materials used throughout the home. The R-value measures the thermal resistance of insulating material. The Department of Energy divides the country into seven climate regions and releases its recommended insulation R-values based on home heating and cooling systems and home partitions.

Attic Insulation

The best choices for attic insulation are blanket or loose fill insulation. Blanket insulation comes in fiberglass rolls and has an R-value between R-2.9 and R-3.8 per inch, while loose fill insulation contains particles of cellulose, fiberglass or mineral wool, and the R-values vary depending on the type of material. For example, loose fill cellulose insulation has an R-value between R-3.2 and R-3.8. Install attic insulation in unfinished attic spaces between the floor joists and in finished attic spaces between the studs and rafters of exterior walls. The Department of Energy recommends that new homes in Zone 2 states -- Alabama, Arizona, Florida, Georgia, Louisiana, Mississippi and Texas -- contain attic insulation with R-values between R-30 and R-60.

Cathedral Ceiling Insulation

The best choice for cathedral ceiling insulation is foil-faced blanket insulation, which comes in fiberglass rolls and has a foil facing that serves as a moisture barrier. It has an R-value between R-2.9 and R-3.8 per inch. In new homes with cathedral ceilings, installing insulation in the joists not only equalizes the temperature balance between the ceiling and room, but helps keeps the temperature constant throughout the home. The Department of Energy recommends homes in Zone 4 states -- Arkansas, California, parts of the Eastern seaboard, Illinois, Indiana, Kentucky, Missouri, New Mexico, Oklahoma, Oregon, Tennessee, Texas and Washington -- contain cathedral ceiling insulation with R-values between R-30 and R-38.

Floor Insulation

The best choice for floor insulation is foam-in-place insulation, which comes in two types. Closed-cell foam insulation contains gas-filled high-density cells and has an approximate R-value of R-6.2 per inch, while open-cell foam insulation contains air-filled cells and has an approximate R-value of R-3.7 per inch. In new homes, floor insulation needs to be installed under floors above cold spaces, floors that extend beyond the outside wall, and slab floors. The Department of Energy recommends homes in Zone 7 states -- Colorado, Maine, Michigan, Minnesota, North Dakota, Wisconsin and Wyoming -- contain floor insulation with R-values between R-25 and R-30.

Wall Insulation

The best choice for wall insulation in new frame home construction is rigid foam insulation, which comes in solid panels. It has an R-value between R-4 and R-6.5 per inch and provides better insulation than comparable materials of the same density. Wall insulation needs to be installed in exterior walls between living spaces, and in unheated adjoining structures such as garages, above-ground foundation walls, and basement walls. The Department of Energy recommends homes in Zone 1 states -- Guam, Hawaii, Puerto Rico and the Virgin Islands -- contain wall insulation with R-values between R-13 and R-15.

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