15 Roofing Felt R Value

The type and amount of roofing felt to apply varies according to roof slope.

15 roofing felt r value. Calculate percent improvement in r value. R3 r18 r21 total roof r value. 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. 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. For many years roofers used asphalt saturated felt under roofing shingles and it was historically available in two standard weights. 15 astm 4869 type i is an authentic 15 astm 4869 type i is an authentic asphalt saturated organic felt underlayment is used as a breathable secondary weather resistant barrier when applied over the roof deck prior to the installation of the primary roofing product. Organic dry felt is made from 100 post consumer recycled material.

If the slope is greater than 4 12 which provides more water drainage from the roof use one layer of 15 felt. If the slope is between 3 12 and 4 12 use two layers of 15 felt for asphalt shingles. 0 87 wood drop 1in. The 15 pound was for lighter weight projects while the 30 offered more heavy duty protection.

The increase r21 r3 exactly 18 the value by which you are increasing the r value. 0 05 wood 0 94 metal any 0 00 ceramic tile in.