1 12 Roof Slopes

A pitch over 9 12 is considered a steep slope roof between 2 12 and 4 12 is considered a low slope roof and less than 2 12 is considered a flat roof.

1 12 roof slopes.

I e 4 inches of rise per 12 inches one foot of run. The table below shows common roof pitches and the equivalent grade degrees and radians for each. Thus pitch is typically greater in areas of high rain or snowfall. See low slope roofing.

Low slope roofs are from 0 to 3 12 in pitch. Clay and concrete roof tiles can only be installed on roof slopes of 2 1 2 12 or greater. What exactly is roof slope. 1 12 roof pitch angle 4 76 degrees.

Roof slopes are most commonly defined by the rise over run ratio. If a roof slope rises say 4 inches when measured 12 inches along the bottom of a horizontal roof truss the roof slope is said to be 4 12. Some sources consider low slope to include 3 12 pitch roofs. Most roof s have a pitch in the 4 12 to 9 12 range.

Slopes greater than 18 12 are found on a frame roofs and some mansard style. The exact roof slope in degrees is given by the arctangent. If a roof rises 1 in a length of 12 this is 1 12 roof pitch. Arctan 3 12 14 0 the primary purpose of pitching a roof is to redirect water and snow.

This means for every 12 horizontal units the roof must rise a minimum of two and one half vertical units. Then you ll be able to measure slope from an unfinished attic space under the roof. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. Definitions vary on when a roof is considered pitched.

Simply locate a roof rafter board place the end of the level against the bottom edge and measure from the 12 inch mark vertically to the bottom edge of the rafter. In degrees 10 2 in 12 or 1 in 6 is considered a minimum. Using a tape measure make a pencil mark 12 inches from the end of a carpenter s level. Built up roofs should be installed on roof slopes 0 25 12 or greater 2015 irc r905 9 1 except for coal tar built up roofs that have a minimum roof slope of one eighth unit vertical in 12 units horizontal 1 slope.

Also if clay and concrete roof tiles are installed on a roof slope of 2 1 2 12 to 4 12 it shall be provided with a double underlayment application.