15 Roofing Felt R Value

15 pounds per hundred square feet and 30 pounds per hundred square feet.

15 roofing felt r value.

The increase r21 r3 exactly 18 the value by which you are increasing the r value. I calculate insulation resistance to heat loss or r percentage improvement always as relative to the original number. 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. The 15 pound was for lighter weight projects while the 30 offered more heavy duty protection.

If the slope is greater than 4 12 which provides more water drainage from the roof use one layer of 15 felt. For many years roofers used asphalt saturated felt under roofing shingles and it was historically available in two standard weights. Organic dry felt is made from 100 post consumer recycled material. Calculate percent improvement in r value.

The type and amount of roofing felt to apply varies according to roof slope. R3 r18 r21 total roof r value. 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. 0 20 siding r value per inch r v per unit wood shingles 16in.

0 05 wood 0 94 metal any 0 00 ceramic tile in. 0 87 wood drop 1in.