Rise Over Run Roof

A 3 in 12 roof rises 3 for every 12 of run.

Rise over run roof.

3 of rise per 12 of run is the same as 1 of rise per 4 of run or 1 4 25. That s the same as a 14 degree slope or a 25 slope. This will give you the rise over run or pitch. The same pitch is also sometimes written as 4 12 4 in 12 or 4 over 12.

The run is the distance from the outside of the wall to the inside of the ridge. For example a roof that rises 4 inches for every 12 inches of run has a 4 12 pitch. Last updated july 10 2020 the following table shows the roof pitch rise in run equivalents for all roof slopes in degrees from 1 to 72. In roof pitch calculator pitch value can be obtained by dividing n by 12 and divide s by the answer.

Why is the roof slope 25. Other than the 45 roof slope which is 12 in 12 none of the standard roof pitches 5 in 12 6 in 12 etc are equal to a whole degree. The horizontal change in distance or the horizontal distance covered by an un supported rafter or truss. Here is an online rise and run calculator which helps to calculate pitch slope and angle with the help of rise and run values.

On a 38 degree sloping roof angle t each individual vertical rise of 9 4 y 1 would have a horizontal run x 1 of 12 inches. 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. Pitch is written assuming a run of a foot or 12 inches so the ratio describes how much the roof rises for every foot of its run.