The R-value measures a material’s resistance to heat flow. The higher the number, the greater its insulating power. The required R-value for a home depends on the climate zone and the location of the insulation (e.g., attic, wall, or floor). A product’s total R-value is determined by multiplying its R-value per inch by its thickness in inches (e.g., a 6-inch thick batt with an R-3.5/inch rating is a total of R-21).
