Insulation R-Value Requirements

R-Value Recommendations

• The United States Department of Energy (USDOE) estimates that most homes are under-insulated by 25 to 50 percent. Adding insulation is one of the most cost-effective ways to reduce energy output and increase home comfort. While utility bills are on the rise, your investment will continue to save economic and natural energy resources. Most current R-value recommendations range from R-22 to R-49. Go to the USDOE website to calculate insulation recommendations and rate of return for your investment.

Increasing R-Value

• Measure the insulation levels in accessible spaces of already built homes. Insulation measuring less than 7 inches will likely need augmentation. If you find your home's R-value is less than the USDOE recommends, then it is usually most economical to add (not replace) insulation. Combining insulation will increase the R-value. For example, if existing insulation measures R-22, then adding more R-22 will increase the R-value to R-44. Different types of insulation can be combined (e.g. cellulose and batts).

R-Values Throughout the Home

• R-value recommendations range throughout the home. The three areas with highest R-value recommendations are the attic, uninsulated floors and unvented crawl spaces. The most important area is the attic. The R-value is highest in the attic because it is the largest heat escape site. The second and third largest areas, uninsulated floors and unvented crawl spaces, are also significant heat escape areas. Basement wall interiors and wood frame wall cavities have lower recommended R-values.

Home Energy Audit

• Consider hiring a home energy auditor before investing in energy conservation home improvements. The home energy auditor will use various tools to find the energy leaks in the building envelope. Aside from insulation recommendations, the auditor may recommend other cost-effective improvements (e.g. electrical outlet covers). Contact your utility company to find qualified home energy auditors in your area. If you are uninterested in a home energy audit, at a minimum, check your home's energy efficiency against those in your area through the Energy Star's Home Energy Yardstick program.