Low Slope Roof Asphalt Shingles

The usual slope for asphalt shingles is a 4 or greater rise for every horizontal foot of run.

Low slope roof asphalt shingles.

Shingles that are not self sealing must be hand sealed with asphalt roofing cement. 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. Cover the entire low sloped roof area with a self adhered modified bituminous membrane that will act as an ice and water. 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.

The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles. They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends. The acceptable underlayment installation options for low slopes are described in the canadian standards association asphalt shingle application standard csa a123 51 as follows. A 3 per foot slope is considered low but may be acceptable if a double layer of felt is used.

Some building codes allow as low as a 2 slope with asphalt shingles if additional steps are taken. What is the minimum slope for an asphalt shingle roof.