R-Value

R-value is defined as the measure of a material's thermal resistance, indicating its ability to resist heat flow. In roofing, R-value applies to the insulation installed in the attic space beneath the roof deck. The Department of Energy recommends attic insulation R-values ranging from R-30 in hot climates (Zone 1) to R-60 in cold climates (Zone 7). Proper attic insulation R-value is critical during a roof replacement because inadequate insulation contributes to ice dam formation, excessive energy costs, and premature shingle aging.