Access one of the rafters then take.
Slope of a roof pitch.
How do you calculate the slope of a roof.
The most precise way to find the roof s slope is by measuring it from the underside.
This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement.
A roof that rises 4 inches for every 1 foot or 12 inches of run is said to have a 4 in 12 slope.
Use a level against the underside of the rafter you re measuring to get the most accurate value.
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 ratio is always expressed as inches per foot.
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.
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.
Locate the level s 12 inch mark.