Take your area result and multiply it by the pitch multiplier or slope correction factor found in the table above to arrive at the roof s surface area.
Roof area conversion factors.
Download the slope chart pdf.
Pitch of roof slope factor valley hip factor.
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 headache of using pythagoras and trigonometry can be spared by making use of these charts.
When scaling a roof size from a drawing multiply roof area x slope factor total area 2 12 roof area x 1 0147 total area 3 12 roof area x 1 031 total area 4 12 roof area x 1 054 total area 5 12 roof area x 1 083 total area 6 12 roof area x 1 118 total area 7 12 roof area x 1 158 total area 8 12 roof area x 1 202 total area.
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.
Now you re ready to price out the materials.
You can consult the following chart to discover the slope factor and hip valley factor.
A 10 slope roof should not be confused with a 10 pitch roof as a 10 slope roof means that the roof rises by ten inches for every foot of run.
The roof slope factor chart also consists of conversion factors to determine the slope of the roof.