Slope Of A Roof Pitch

The most precise way to find the roof s slope is by measuring it from the underside.

Slope of a roof pitch. The slope is the measurement of the rise of the roof to the run of the roof and is expressed as inches per foot in a ratio format. This ratio is always expressed as inches per foot. The table below shows common roof pitches and the equivalent grade degrees and radians for each. The run is the measurement from the outside of one wall s top plate to a point directly below the center of the ridge picture a right triangle.

This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. 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. Use a level against the underside of the rafter you re measuring to get the most accurate value. Locate the level s 12 inch mark.

Squaring building lines example 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. A roof that rises 4 inches for every 1 foot or 12 inches of run is said to have a 4 in 12 slope. Access one of the rafters then take.