Home Insulation and R-Values

By Mark J. Donovan

Sufficient and proper insulation in the home is critical for keeping your home both toasty warm during the winter months and comfortably cool during the summer months.

When buying a new home, make sure the home inspection includes an assessment of the insulation situation within the home. Make sure the insulation is compliant to your local building codes, and preferably to the U.S. Department of Energy insulation R-Value guidelines. Note that there are different R-value guidelines for different portions of the home, e.g. walls, ceilings, in between floors. The U.S. DOE also provides different R-value guidelines for different regions of the country. For example in the upper New England area the recommend attic R-value is R-49, whereas in Florida it is R-38.

Note that R-value is a term for describing the resistance level to heat flow. The higher the R-value the higher the resistance to heat flow transfer. Depending upon the type of insulation used, the R-value varies between a value of 3 and 4 per inch of insulation thickness. For example a typical fiberglass insulation batt has an R-value of 3.14. Consequently an R-value of R-19 batt insulation is approximately 6 inches thick.

There are four main types of insulation used in the home and they include:

Batt or Blanket insulation - This is your standard fiberglass or Rockwool insulation material. It is used frequently in homes, and slides easily in between wall studs and floor and ceiling joists.

Rigid foam insulation - This is used frequently against basement walls.

Blown in Insulation – This is chemically treated, shredded newspaper that is blown into walls, attics, and between floor joists.

Spray Insulation – This is a two part liquid material that is sprayed onto walls, and between attic and flooring bays. As it hits the surface area it quickly expands and hardens to form a tight and highly insulated barrier.