Roof Pitch Factors

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.

Roof pitch factors. Roof pitch factor calculator. 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. Low pitch roofs are safer and easier to access when maintenance. Since a low pitch roof doesn t require as many shingles more often than not a low pitch roof will end up being more.

The pitch is defined as the slope of the roof and is commonly represented as the ratio of the rise over the run in the form x 12. Multiply the result by the factor and this is the length of the roof from base to ridge. For example suppose you have a 4 12 pitch roof and the width of the house is 28 feet. The leftover part is very simple as it simply involves mathematics.

From the roof pitch factor table note down the roof pitch conversion factor corresponding to the roof pitch calculated. Roof pitch and corresponding angles. 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. If you have already decided that you are going to have pitched roof on your house then you have made a nice decision.

This will give you the rise over run or pitch. In our example the roof pitch was calculated as 9 12 which has a factor of 1 25 in the table. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. Especially for homes in the south a low pitch roof.

For example if you measure 4 inches the pitch of your roof is 4 12. If a roof increases in height by four inches for every foot of horizontal run it is considered to have a 4 in 12 pitch or just a 4 pitch talk in terms of pitches and you will always be understood in the roofing universe. Looking at the chart the factor is 1 0541. Roof pitch factor the roof pitch is a measure of roof steepness.

Dividing the house width by two equals 14 feet. Pitched roof provide you protection again heavy rains. The lower pitch of the roof means greater walkability. So the pitch of a roof is determined by how many inches the slope rises for every 12 inches it runs horizontally.

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.