1 12 Roof Slopes

What exactly is roof slope.

1 12 roof slopes.

Arctan 3 12 14 0 the primary purpose of pitching a roof is to redirect water and snow. The table below shows common roof pitches and the equivalent grade degrees and radians for each. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. Slopes greater than 18 12 are found on a frame roofs and some mansard style.

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. Some sources consider low slope to include 3 12 pitch roofs. 1 12 roof pitch angle 4 76 degrees.

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. The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7. In degrees 10 2 in 12 or 1 in 6 is considered a minimum. Definitions vary on when a roof is considered pitched.

See low slope roofing. I e 4 inches of rise per 12 inches one foot of run. Thus pitch is typically greater in areas of high rain or snowfall. Metal roof panels should be installed on roof slopes according to particular seams 2015 irc r905 10 2.

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. If a roof rises 1 in a length of 12 this is 1 12 roof pitch. Then you ll be able to measure slope from an unfinished attic space under the roof. The exact roof slope in degrees is given by the arctangent.

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. 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. If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks. Roof slopes are most commonly defined by the rise over run ratio.

This means for every 12 horizontal units the roof must rise a minimum of two and one half vertical units.