Another method to find the roof pitch is to go into the attic and measure the rise.
Roof multiplier for pitch.
Measure from the roof.
A roof pitch multiplier also known as a roof pitch factor is a number that when multiplied by the area covered by a sloped roof gives the actual area of the roof.
Roof is 6 12 pitch and measures at 2 400 square feet so 2400 x 1 12 2 688 2 88 sqs added for pitch.
Now you re ready to price out the materials.
If the home measures 20 x 40 and has a 7 12 roof then to calculate the slope of the roof follow these steps.
Step by step example using the roof pitch multiplier table measure the area covered by the roof.
Take the area of the roof s footprint say it s 5 000 square feet and multiply 5 000 by 1 118.
So the actual roof surface if it were laid down flat on the ground would be 1 118 times larger than the footprint of the roof.
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.
Step 2 find the value of 7 12 from the roof slope multiplier table which is 1 16.
That gives you 5 590 square feet which is the actual area of the surface of the roof.
And for a roof with a slope of 6 12 that number 1 118 is your roof slope multiplier.
The maths behind this number is that it is the square root of rise run 2 1.
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.
Let s assume the pitch is 8 12.
Get your roof size by using this roof pitch calculator.
Step 1 multiply 20 and 40 which equals 800.
You might like to use this roof slope calculator.
One method to find the pitch is to climb on the roof and measure the rise for a 12.
Calculate the slope of the roof.
2280 1900 380 feet added for pitch.
For this example let s assume your roof covers an area that is 20 feet wide and.
Enter your numbers into this go to roof pitch calculator.