Slope Of A Roof Pitch

Locate the level s 12 inch mark.

Slope of a roof pitch.

Access one of the rafters then take. Use a level against the underside of the rafter you re measuring to get the most accurate value. The table below shows common roof pitches and the equivalent grade degrees and radians for each. 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.

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. This ratio is always expressed as inches per foot. 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. 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.

Most roof s have a pitch in the 4 12 to 9 12 range. 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. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement.