1 12 Roof Slopes

Then you ll be able to measure slope from an unfinished attic space under the roof.

1 12 roof slopes.

Definitions vary on when a roof is considered pitched. See low slope roofing. Using a tape measure make a pencil mark 12 inches from the end of a carpenter s level. Thus pitch is typically greater in areas of high rain or snowfall.

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. 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. Metal roof panels should be installed on roof slopes according to particular seams 2015 irc r905 10 2.

This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks. 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. Arctan 3 12 14 0 the primary purpose of pitching a roof is to redirect water and snow.

Slopes greater than 18 12 are found on a frame roofs and some mansard style. I e 4 inches of rise per 12 inches one foot of run. Low slope roofs are from 0 to 3 12 in pitch. If a roof rises 1 in a length of 12 this is 1 12 roof pitch.

Clay and concrete roof tiles can only be installed on roof slopes of 2 1 2 12 or greater. This means for every 12 horizontal units the roof must rise a minimum of two and one half vertical units. 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. What exactly is roof slope.

The exact roof slope in degrees is given by the arctangent. In degrees 10 2 in 12 or 1 in 6 is considered a minimum. 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. Most roof s have a pitch in the 4 12 to 9 12 range.

The table below shows common roof pitches and the equivalent grade degrees and radians for each.