Insulation warmth is measured in R-value, and is always indicated on the packaging. Different climates have different recommendations for R-values, so local stores will likely indicate what ratings are useful in your neighborhood for walls, ground floors, and attics. Different types of insulation include fiberglass, cellulose and rigid foam board. Fiberglass is itchy, but fairly easy to lay. Cellulose is shredded newspaper, and warmer than fiberglass, but is usually blown in by experts. Cellulose should not be used near anything flammable, such as a chimney or recessed lights. After laying fiberglass in an attic, it can be useful to sprinkle cellulose in the seams (Harley, 2012). Foam board is high-performance and rigid, but only 1 inch thick.
Attic Insulation: For attics, R-38 is the minimum recommended, increasing for northern climates to R-50 or R-60 (Harley, 2012). To estimate your attic insulation level, determine the insulation type, learn its R-rating, and measure the thickness of the insulation. To add insulation, lay new batts down vertically across existing insulation (Amann et al., 2012). Harley (2012) says you will benefit the most from the first 6 inches of insulation but gain savings from the next 6 inches. Fiberglass and cellulose insulation must be fluffed to achieve the R-rating advertised on the packaging. It is recommended to wear a respirator and safety glasses when installing new insulation, to protect yourself from the new – and any existing – insulation. Older insulation, such as brown and grainy vermiculite, may contain traces of dangerous asbestos.
Wall Insulation: Homes built before 1960 may have little to no insulation in the walls. Cellulose insulation can be blown in by drilling holes in the external siding (wood, vinyl or shingle siding). Someone should be inside monitoring for problems, e.g., insulation falling into the basement (Harley, 2012). Basement foundation walls also benefit from insulation but must be done expertly to avoid mold issues (Amann et al., 2012).
An energy auditor will make professional insulation recommendations. Also read section on Seal House Envelope for additional insulation ideas.
References
- Harley, Bruce (2012) Insulate and Weatherize for Energy Efficiency at Home. The Taunton Press, Newtown CT.
- Amann, Jennifer Thorne, Wilson, Alex, and Ackerly, Katie (2012) Consumer Guide to Home Energy Savings, 10th edition. New Society Publishers, Gabriola Island, BC Canada.