Rise Over Run Roof Pitch

Enter the rise and run for the pitch length and angle of the rafter.

Rise over run roof pitch.

A roof pitch that is based on a fixed rise and run and does not end up with a whole number is known as a bastard pitch. The same pitch is also sometimes written as 4 12 4 in 12 or 4 over 12. Roof pitch is often expressed as a ratio between rise and run in the form of x 12. Roofers express roof slope as rise or pitch measured in inches of vertical rise per foot of horizontal distance or run.

Roof pitch is simply the slopecreated by the rafter. I e 4 inches of rise per 12 inches one foot of run. Pitch is the incline of the roof represented as the ratio of rise to the span twice the run. Drag sliders to animate the results and diagram.

This is rarely is a whole number it is not a rare event and it is not a nightmare. Enter run the flat level length then click pitch angle or rise to select then enter other known dimension angle or pitch. Roof slopes are most commonly defined by the rise over run ratio. Roof pitch or slope is a measure of vertical rise to horizontal run expressed in inches per foot.

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. 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. It just means the top of the roof has to end out at a specific place. For example if the roof rises 4 feet and the span is 16 feet twice the run then the pitch is 4 16 or 1 4.

Pitch is thus the ratio of the rise in inches to a 12 inch run and is often expressed using a semicolon for example 6 12. So a 3 inch rise roof also described as a 3 in 12 roof means that for every 12 or foot of horizontal distance the height of the roof increases by 3. A a roof with a 6 rise for every 12 run has a 6 per foot or 6 in 12 pitch. Here is an online rise and run calculator which helps to calculate pitch slope and angle with the help of rise and run values.

The triangle diagram will be re drawn to scale with all dimensions marked. For example a roof that rises 4 inches for every 12 inches of run has a 4 12 pitch. The following table shows the roof pitch rise in run equivalents for all roof slopes in degrees from 1 to 72. Visit this page using a phone or tablet to directly measure pitch and angles.

Roof pitch calculator the rise is the distance from the top of the roof to the bottom.