Min Roof Slope For Asphalt Shingles

The 2 12 number is rise over run or two units of vertical for every 12 units horizontal.

Min roof slope for asphalt shingles.

Also if asphalt shingles are installed on a roof slope of 2 12 to 4 12 it shall be provided with a double underlayment application. The requirements for an asphalt shingles roof are contained in the international building code. Asphalt shingles can only be installed on roof slopes of 2 12 or greater. The minimum requirement is 2 12.

The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles. Asphalt shingle roofing is designed to shed water that is flowing downward over its surface with each shingle overlapping the one below. For asphalt shingle clay and concrete tile metal shingle slate and wood shake and shingle roof systems nrca recommends slopes of 4 12 or more. Pitch is measured in inches of vertical rise of the roof over one foot 12 inches of horizontal run.

That works out to about nine degrees if that works better for you. The minimum slope for an asphalt shingle roof is 2 12. Asphalt composition shingles are designed to be installed on roof slopes greater than a 4 in 12 pitch. Run in degrees and as percentage the minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems.

The roof pitch between 2 12 and 4 12 is considered as a low pitch roof so shingles can be installed in the roof slope between 2 12 and 4 12. Roof slope equivalents as rise. There are differing opinions as to the minimum slope for a roof but the generally accepted minimum is 3 12. Shingles of all types need to have a slope to function properly.

Nrca s recommended minimum roof slope guidelines for steep slope roof systems generally are greater at steeper inclines than those in the building code. This number corresponds to the number of inches of rise in a 12 foot run. This means for every 12 horizontal units the roof must rise a minimum of 2 vertical units. Some people recommend not installing asphalt shingles on slopes below 5 12 but a skilled roofer may well be able to make this work.

So a 4 12 pitch roof rises 4 inches for every 12 inches of horizontal run. Therefore the asphalt manufactures base their warranties around the minimum recommended pitch of 4 in 12. They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends. What is the minimum pitch slope of an asphalt shingle roof.

For every 12 inches you travel on your ceiling the roof will rise 4 inches in height. According to this code the minimum slope for asphalt shingles is 17 degrees or two vertical units to twelve units in the horizontal. The following table provides the minimum required. For those who don t understand the roof pitch number here is a way to envision it.