Roof Pitch Factor Table

Two most common methods 4 12 or 4 12 are used for marking the pitch of a roof.

Roof pitch factor table.

This will give you the rise over run or pitch. This means if a roof rises 4 in the length of 12 your roof pitch would be 4 12 or 18 43 degrees. For example if the pitch of the roof is 6 then it is written as 6 12. Roof pitch refers to the slope which the rafter creates.

A roof pitch multiplier also called a roof pitch factor is a number that is multiplied by the area covered by a sloped roof to produce the area of the actual surface of the roof. Some sources consider low slope to include 3 12 pitch roofs. 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. For example if you measure 4 inches the pitch of your roof is 4 12.

The whole table of roof pitch and slope gives a conversion factor so as to obtain a numerical figure of the slope. Often you express roof pitch as the ratio between the rise and the run in the form of x 12. Therefore it s important to understand the roof pitch chart process completely. The hip and valley factor varies according to the slope of the roof as shown in the table below.

Notes to the table above 1. 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. 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. 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.

The combination of two numbers are used to display or show the roof pitch. Divide the rise by the run the run is 12. 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. One medium to describe the roof pitch is in 12 runs.