What R-Value Insulation Do I Need? When choosing insulation, you need to determine the overall R-value of the insulation you need for your home. The definition of R-value according to the North American Insulation Manufacturers Association is the resistance to heat flow, therefore:
The higher the R-value, the greater the insulating power. Thickness of insulation is only one factor that determines its R-value. In fact, insulation should always be specified by R-value, not thickness.
To find out the R-value of the insulation you need for your new or existing home, try this Zip Code calculator or see this R-value table from the U.S. Department of Energy.