what is the insulation r value for attic
Depending on where you live, itâs recommended that attics have a minimum R-value of R-30 in warm climates to R-60 in cold climates. Recommended Insulation by Climate. By dividing the recommended R-value for your area by the R-value of your particular type of insulation, you find that an attic should have on average: Warm Climates (R-30 to R-49): 1  Fiberglass (blown): 14â â 18â. 2  Fiberglass (batts): 11â â 14â. 3  Cellulose (blown): 11â â 13â. 4  Rock Wool (loose): 12â â 18â. 5  Foam (sprayed): 5â â 11â.