Roof Pitch Ratio

Roof pitch is often expressed as a ratio between rise and run in the form of x 12.

Roof pitch ratio.

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. A a roof with a 6 rise for every 12 run has a 6 per foot or 6 in 12 pitch. A ratio of the ridge height to the width of the building span and as a ratio of the rafter length to the width of the building. 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.

They do not mean the same thing. A 12 to 24 pitch is expressed as 1 2. Roof pitch or slope is a measure of vertical rise to horizontal run expressed in inches per foot. 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.

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. Roof pitch is simply the slope created by the rafter. You can assess this in two ways either as the roof pitch angles which the rafters make with the horizontal or the proportion between the run and the rise of the roof. Roof pitch refers to the slope which the rafter creates.

A ratio of 1 1 62 is known as the golden ratio and therefore the vast majority of roof pitch in degrees charts you see will be working to this ratio at the very least. The ridge height is 1 9 to 1 7th the span an angle of 12 5 to 16. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. The term pitch and slope are often used interchangeably which is incorrect.

So the pitch of a roof is determined by how many inches the slope rises for every 12 inches it runs horizontally. For example given a roof with a rise of 4 feet and a span of 24 feet the pitch is 1 to 6 pitch which can be expressed as the fraction of 1 6. Historically roof pitch was designated in two other ways. Pitch is the incline of the roof represented as the ratio of rise to the span twice the run.

For example a pitch 1 12 means that per every twelve yards of building length the rise will be equal to one yard. Commonly used roof pitches were given names such as greek.