Rise Over Run Roof Pitch

Roof slopes are most commonly defined by the rise over run ratio.

Rise over run roof pitch.

Roof pitch is simply the slopecreated by the rafter. Visit this page using a phone or tablet to directly measure pitch and angles. 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. Enter the rise and run for the pitch length and angle of the rafter.

Roof pitch or slope is a measure of vertical rise to horizontal run expressed in inches per foot. Roof pitch is often expressed as a ratio between rise and run in the form of x 12. 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. Here is an online rise and run calculator which helps to calculate pitch slope and angle with the help of rise and run values.

Roofers express roof slope as rise or pitch measured in inches of vertical rise per foot of horizontal distance or run. 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. Pitch is the incline of the roof represented as the ratio of rise to the span twice the run. I e 4 inches of rise per 12 inches one foot of run.

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. It just means the top of the roof has to end out at a specific place. For example a roof that rises 4 inches for every 12 inches of run has a 4 12 pitch. The triangle diagram will be re drawn to scale with all dimensions marked.

A a roof with a 6 rise for every 12 run has a 6 per foot or 6 in 12 pitch. It can be assessed in two ways either as the angle the rafter makes with the horizontal or the proportion between the rise and the run of the roof. 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. The same pitch is also sometimes written as 4 12 4 in 12 or 4 over 12.

Enter run the flat level length then click pitch angle or rise to select then enter other known dimension angle or pitch. The run is the distance from the outside of the wall to the inside of the ridge. 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. 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.

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