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.
Low slope roof shingles.
Shingles that are not self sealing must be hand sealed with asphalt roofing cement.
Low slope roofs present a challenge where water is concerned.
Cover the entire low sloped roof area with a self adhered modified bituminous membrane that will act as an ice and water.
A 3 per foot slope is considered low but may be acceptable if a double layer of felt is used.
However those naysayers would be wrong.
Low slope roofing shingles.
3 tab shingles versus laminated shingles for low slope roof.
The usual slope for asphalt shingles is a 4 or greater rise for every horizontal foot of run.
Some will argue that shingles shouldn t be used for low pitch roofs at all.
And by the way the manufacturers instructions i reviewed for the shingles i was interested in buying described installations down to a 2 12 pitch.
The acceptable underlayment installation options for low slopes are described in the canadian standards association asphalt shingle application standard csa a123 51 as follows.
If you have a low slope roof but would love to have a shingled look rather than other solutions like rolled sheet roofing you are in luck.
Some building codes allow as low as a 2 slope with asphalt shingles if additional steps are taken.