Can You Use Blow-In Insulation on Top of Batt Insulation?

Home Energy Audit

• Before adding insulation to an existing home, it is usually worth the investment to hire a qualified energy auditor, who will identify insulation needs and recommend other energy saving improvements. Auditors use blower doors, infrared cameras, and similar tools to determine leaks in the building envelope. Contact your local utility company to find certified home energy auditors. If your budget does not allow for a professional, or you do not need specific recommendations, you can assess your home's energy efficiency against those in your area through Energy Star's Home Energy Yardstick program. You will need 12 months of utility bills and basic information on your home.

Safety of Insulation

• The two choices when dealing with existing insulation are add to it or replace it. If you are unsure of the type of insulation (especially if it is an older home) consider replacing it. Insulation made up of vermiculite (a natural occuring mineral) from Libby, Montana, contains asbestos. The contaminated mine in Libby provided more than 70 percent of all vermiculite sold between 1919 and 1990 in the U.S. If your insulation is made up of vermiculite, then assume it contains asbestos and hire a professional.

Insulation Needs

• While most homeowner's have under-insulated homes; determine how much insulation is needed in your area before starting this project. U.S. building codes are based on geographical climate and range from R-22 to R-49. Insulation is needed in almost all instances where insulation measures less than seven inches (R-22). Go the the United States Department of Energy website and calculate the most economical insulation level for your region.

R-Value Meaning

• To protect consumers, the Federal Trade Commission has stringent rules on the R-value standard.The R-value indicates thermal resistance, and the higher the number the greater its effectiveness. The type of material, thickness, and density play a role in the R-Value. If blown-in insulation is added to batt insulation the R-values of both products are combined.
  R-values are not as effective when compressed. Compression happens when a denser insulation is added on top of a lighter one. Therefore, it is better to put the batt down first, then the lighter blown-in insulation.