Roof Pitch Factor Table

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 factor table. Roof pitch refers to the slope which the rafter creates. For roof slopes expressed as x in 12 rise in run the roof pitch multiplier is determined by finding the square root of rise run 1. Therefore it s important to understand the roof pitch chart process completely. This means if a roof rises 4 in the length of 12 your roof pitch would be 4 12 or 18 43 degrees.

This numerical figure is significant as not everybody can understand the technical measurements. Low slope roofs are from 0 to 3 12 in pitch. 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. The horizontal measurement or roof run and the vertical measurement the roof rise are the most important factors to get right when making the roof pitch calculations that you need to make.

Notes to the table above 1. This will give you the rise over run or pitch. Two most common methods 4 12 or 4 12 are used for marking the pitch of a roof. For any roof slope expressed as x in 12 rise in run the hip and valley factor is determined by finding the square root of rise run 2.

The hip and valley factor varies according to the slope of the roof as shown in the table below. For example if the pitch of the roof is 6 then it is written as 6 12. On blue prints architects engineers usually display the pitch of a roof in the format shown on the image where number 4 represents a rise and number 12 represents a length. The whole table of roof pitch and slope gives a conversion factor so as to obtain a numerical figure of the slope.

The combination of two numbers are used to display or show the roof pitch. Some sources consider low slope to include 3 12 pitch roofs. One medium to describe the roof pitch is in 12 runs. Divide the rise by the run the run is 12.