Roof Insulation Thickness R Value

Recommended insulation levels for retrofitting existing wood framed buildings.

Roof insulation thickness r value.

Thickness inches r value in i p imperial rsi r value in metric 0 5. R value measures how well certain building insulation materials can resist heat. All these have r values ranging from r 3 2 to r 3 8 per inch. Existing 3 4 inches of insulation.

Depending on where you live and the part of your home you re insulating walls crawlspace attic etc you ll need a different r value. Closed cell spray foam has a far better r value per inch than other less effective insulations like cellulose fiberglass or even open cell foam. The higher the r value the greater the insulation performance. Know exactly how much you need with our project calculators.

Typical recommendations for exterior walls are r 13 to r 23 while r 30 r 38 and r 49 are common for ceilings and attic spaces. The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13. R value chart for enerfoil tm rigid foam faced insulation. When determining how much insulation you need don t guesstimate calculate.

Conditioned per atsm c1289 test method astm c5181 2. Closed cell spray foam insulation.