15 Roofing Felt R Value

R3 r18 r21 total roof r value.

15 roofing felt r value.

The type and amount of roofing felt to apply varies according to roof slope. The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures. The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process. 0 20 siding r value per inch r v per unit wood shingles 16in.

Organic dry felt is made from 100 post consumer recycled material. I calculate insulation resistance to heat loss or r percentage improvement always as relative to the original number. Calculate percent improvement in r value. If the slope is greater than 4 12 which provides more water drainage from the roof use one layer of 15 felt.

The 15 pound was for lighter weight projects while the 30 offered more heavy duty protection. 0 87 wood drop 1in. For many years roofers used asphalt saturated felt under roofing shingles and it was historically available in two standard weights. 15 pounds per hundred square feet and 30 pounds per hundred square feet.

Roofing r value per inch r v per unit roofing felt 0 06 asphalt roll 90 lb 0 15 asphalt shingle 0 44 slate in. If the slope is between 3 12 and 4 12 use two layers of 15 felt for asphalt shingles.