ECM: Building Envelope

Information by State  Print version   CAUTION STATEMENT TURN OFF UTILITIES: Turn off electricity, gas, propane, and other utilities before starting repairs, cleaning, or installations to avoid accident or injury. BE AWARE OF LEAD-BASED PAINT HAZARDS: Many residences built before 1978 have paint that contains lead, which can pose a serious health hazard if paint, chips, and dust are not handled properly. See the U.S. Environmental Protection Agency (EPA) lead brief before disturbing painted surfaces in homes of this vintage. Follow the HUD “Lead-Safe Housing Rule” for requirements for notification, evaluation and reduction of lead-based paint hazards. BE AWARE OF ASBESTOS HAZARDS: Homes older than 1977 may have building products that contain asbestos such as insulation, high-temperature gaskets, roofing and siding shingles, and vinyl sheet flooring. See the EPA asbestos brief before disturbing such materials. BE AWARE OF MOLD AND MOISTURE HAZARDS: Molds can gradually destroy materials they grow on; can irritate the eyes, skin, nose, throat, and lungs of both mold-allergic and non-allergic people; can cause asthma attacks in people with asthma who are allergic to mold; and can cause other serious health problems. To learn more about preventing and cleaning up mold in homes, see these mold guides and the EPA brief on What to Wear When Cleaning Moldy Areas.

B5. Install/Increase Attic Insulation

Description

Attic insulation reduces the amount of heat that flows from a dwelling unit through the attic to the cold outside air. By reducing this heat loss, attic insulation reduces the amount of energy needed to heat the dwelling unit in the winter. In the summer, attic insulation saves on cooling costs and keeps buildings more comfortable by reducing the conduction of heat from the hot attic through the ceiling and into the unit.

A material’s resistance to heat flow is measured in units of “R-value”. The higher the R-value, the better the insulating properties. The R-value of insulation depends on the type of insulation and its thickness. Optimal R-value for attic insulation depends on the existing insulation, fuel costs, and climate.

Applicability

• Single-family and low-rise multifamily buildings with attics
• Attics that currently have less than 12 inches of insulation

• Batt insulation, also called rolls and blankets
  • fiberglass
  • rock wool
• Loose-fill insulation
  • fiberglass
  • rock wool
  • cellulose

Considerations

• Insulation must be installed according to manufacturer’s directions. Unless the attic is used as a habitable space, attic insulation should be installed between the rafters of the attic floor, rather than the attic ceiling.
• A vapor barrier must be present on the warm side of insulation to prevent moisture problems.
• Recessed lights or fans that protrude into the attic space should not be covered by insulation.
• Insulation should not obstruct vents or louvers.
• Installation crews should wear protective gloves and masks.
• Installation must comply with local fire codes.
• Loose-fill cellulose insulation must be a fire-retardant type.

Performance/Economics

• Installing attic insulation is relatively easy, inexpensive, and cost effective.
• In mild climates, adding insulation where some attic insulation already exists can produce fuel savings ranging from 13 to 21 percent.

Resources/Links

Energy Conservation for Housing – A Workbook, HUD, September 1998. Pages 7-25 through 7-28 address attic insulation, applications, and effectiveness.

Attic Insulation. Part of the U.S. Department of Energy's Consumer's Guide.

HUD Energy Efficicent Rehab Advisor. Discusses Insulation Basics.

DOE Insulation Guidance. Information on insulation levels for existing and new homes from the U.S. Department of Energy.

Consumer Guide to Home Energy Savings, American Council for an Energy Efficient Economy, 1999, ISBN 0-918249-38-4. Pages 21 through 27 address attic insulation methods and strategies. 

Insulation and Air Sealing. Part of the U.S. Department of Energy's Consumer Guide. Discusses both air leakage and moisture control

The Home Energy Saver. Addresses attic insulation, including strategies and effectiveness. 

ENERGY STAR Program: Home Sealing. Provides information on insulation strategies, recommendations, and links to other information resources.

Simply Insulate. A website of the North American Insulation Manufacturers Association that provides a variety of information about the benefits of insulating homes. Features include installation information and tools that determine the necessary insulation in your state and your projected energy savings.