Low Slope Roof Asphalt Shingles

The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.

Low slope roof asphalt shingles.

When combined with the proper underlayment materials and application they are an excellent solution for a low slope roof with a pitch between 2 12 to 4 12. Because of the non absorbent nature of asphalt the shingles themselves provide an element of waterproofing which is why they work well for low slopes. What is the minimum slope for an asphalt shingle roof. A 3 per foot slope is considered low but may be acceptable if a double layer of felt is used.

This low slope application requires a double layer of 15 felt underlayment cemented together for a distance extending from the eaves up to a point 24 inches inside the interior wall line of the building. Some building codes allow as low as a 2 slope with asphalt shingles if additional steps are taken. They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends. Shingles that are not self sealing must be hand sealed with asphalt roofing cement.

The arma s residential manual for asphalt roofing recommends that asphalt shingles on low slope roofs be applied over a nonperforated single layer of adhesive backed bituminous membrane installed to the manufacturer s specifications or over a double layer of asphalt impregnated felt paper. The acceptable underlayment installation options for low slopes are described in the canadian standards association asphalt shingle application standard csa a123 51 as follows.