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.

This numerical figure is significant as not everybody can understand the technical measurements. 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. The combination of two numbers are used to display or show the roof pitch. This will give you the rise over run or pitch.

Often you express roof pitch as the ratio between the rise and the run in the form of x 12. One medium to describe the roof pitch is in 12 runs. 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. 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.

Divide the rise by the run the run is 12. This means if a roof rises 4 in the length of 12 your roof pitch would be 4 12 or 18 43 degrees. Therefore it s important to understand the roof pitch chart process completely. 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 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. Roof pitch refers to the slope which the rafter creates. For example if the pitch of the roof is 6 then it is written as 6 12. Low slope roofs are from 0 to 3 12 in pitch.

Some sources consider low slope to include 3 12 pitch roofs. Two most common methods 4 12 or 4 12 are used for marking the pitch of a roof. 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 hip and valley factor varies according to the slope of the roof as shown in the table below.