Divide the rise by the run the run is 12.
Multiplier for 3 12 roof.
The calculator above can handle much of this math.
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 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.
Take the area of the roof s footprint say it s 5 000 square feet and multiply 5 000 by 1 118.
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.
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.
Outside of the u s a degree angle is typically used.
Roof pitch degree table.
We excluded roof multipliers for pitch below 3 and above 12 for the following reasons.
Roof pitch is a determining factor for cost of the roof as well as the roof area and the type of materials used.
The pitch of this roof is 4 8 12.
48 10 4 8.
Roof pitch area multipliers.
The pitch of the roof is the rise over a 12 inch run.
The value arrived at 928 reflects the square feet of the roof.
100 1 054 105 4ft 2.
Multiply step 1 and step 2 i e.
This will give you the rise over run or pitch.
Now divide the rise by the multiplier to get the pitch eg.
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.
Find the value of 7 12 from the roof slope multiplier table which is 1 16.
800 multiplied by 1 16.
And for a roof with a slope of 6 12 that number 1 118 is your roof slope multiplier.
We included a roof pitch chart below the 7 12 example image and the calculator below that.
It affects walkability as well as drainage and roofs in areas of high rain.
Multiply 20 and 40 which equals 800.
For example if you measure 4 inches the pitch of your roof is 4 12.
With pitch under 3 you can easily walk on the roof to get the exact measurements as that is usually a flat roof.
Image 1 12 to 12 12 roof pitch 7 12 pitch.
Use our roof pitch calculator to find the pitch of your roof.
If the home measures 20 x 40 and has a 7 12 roof then to calculate the slope of the roof follow these steps.
If this isn t practical then perform the same measurement on the underside of the roof.
Also the multiplier is so close to one that it does not really change the total size unless your roof is something like a 100 100.
Next multiply the footprint of the roof by the multiplier below for your roof pitch to find the overall roof area.
Get your roof size by using this roof pitch calculator.
