Roof Slope Ratios

Often you express roof pitch as the ratio between the rise and the run in the form of x 12.

Roof slope ratios.

If the rise is 6 inches for every 12 inches of run then the roof slope is 6 in 12 the slope can be expressed numerically as a ratio. The ridge height is 1 9 to 1 7th the span an angle of 12 5 to 16. This will give you the rise over run or pitch. The following table shows how the same common roof slopes can be expressed using rise in run ratios degrees and percentages.

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. Commonly used roof pitches were given names such as greek. Roof slope expressed as rise in run degrees and percentage. Last updated july 10 2020.

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. Slope ratio a roof that rises 4 inches for every 1 foot or 12 inches of run is said to have a 4 in 12 slope. 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 you measure 4 inches the pitch of your roof is 4 12.

Roof pitch refers to the slope which the rafter creates.