Roof Slope Defined

The ratio can be indicated by a division slash separating the numbers such as 2 12 or 7 12.

Roof slope defined.

However most often a ratio of pitch also fraction is slang used for the more useful slope of rise over run of just one side half the span of a dual pitched roof. Roof slope can also be described as the angle of change in elevation expressed in one of several forms. Roof slopes are most commonly defined by the rise over run ratio. A roof that rises 4 inches for every 1 foot or 12 inches of run is said to have a 4 in 12 slope.

I e 4 inches of rise per 12 inches one foot of run. 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. In the roofing trade the go to term is pitch and it is expressed in terms of 12 inches so the pitch of a roof is determined by how many inches the slope rises for every 12 inches it runs horizontally. Definition of roof slope.

Slope is the incline of the roof expressed as a ratio of the vertical rise to the horizontal run where the run is some portion of the span. The pitch of a roof is its vertical rise over its horizontal span. Pitch angle incline slope they all can be used to refer to the steepness of a roof. Some sources consider low slope to include 3 12 pitch roofs.

Roof pitch designations are comprised of two numbers indicating a ratio. This ratio is always expressed as inches per foot. Slopes greater than 18 12 are found on a frame roofs and some mansard style roofs. 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 slope is the amount of vertical change in height as a ratio of horizontal distance traveled also expressed as inches of rise per foot of horizontal run or cm of rise per m of horizontal run. 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. See low slope roofing.