Divide the first part of the ratio by 12 to work out the pitch.
12 12 roof pitch multiplier.
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 the home measures 20 x 40 and has a 7 12 roof then to calculate the slope of the roof follow these steps.
C sqrt 5 2 12 2 sqrt 169 13 in.
If this isn t practical then perform the same measurement on the underside of the roof.
The calculator above can handle much of this math.
Image 1 12 to 12 12 roof pitch 7 12 pitch.
For example a roof with a pitch of 1 cannot use metal shingles.
Then the roof multiplier is.
800 multiplied by 1 16.
Now divide the rise by the multiplier to get the pitch eg.
The value arrived at 928 reflects the square feet of the roof.
Multiply 20 and 40 which equals 800.
Helps determine what materials are suitable for your roof.
To convert between american roofing ratios and pitch degrees follow these steps.
For example if you measure 4 inches the pitch of your roof is 4 12.
Roof pitch multiplier 13 over 12 1 08.
So in this case for every 12 inches the roof goes across horizontally b while rising 6 inches a there s actually 13 416 inches of roof c.
Roof is 6 12 pitch and measures at 2 400 square feet.
We included a roof pitch chart below the 7 12 example image and the calculator below that.
Using the pythagorean theorem we find that for every 12 inches the roof spans horizontally there are 13 inches of actual roof.
Get your roof size by using this roof pitch calculator.
Roofers typically refer to it as a pitch and can be found by factoring the rise over a 12 inch run.
Find the inverse tangent of the pitch to find the angle in degrees.
Once you know the roof slope multiplier for a particular slope you can use it to find the actual area of any size sloped roof with the same slope.
The pitch of this roof is 4 8 12.
What is the multiplier.
Find the value of 7 12 from the roof slope multiplier table which is 1 16.
Roof pitch degree table.
Since pitch is the rise over a 12 inch run divide the run by 12 to get the multiplier in this case 120 12 10.
Why figure what your roof pitch is.
A 12 12 pitch roof has a pitch angle of 45.
48 10 4 8.
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.
This will give you the rise over run or pitch.
So 2400 x 1 12 2 688 2 88 sqs added for pitch.