Step 1 multiply 20 and 40 which equals 800.
Roof square footage multiplier.
Next multiply the footprint of the roof by the multiplier below for your roof pitch to find the overall roof area.
So continuing our example if you ve got a two story house with a total square footage of 2 700 square feet with each floor having.
Multiply by the square footage of a single floor of your house.
A roof pitch of 4 in 12 4 12 has a rise of 4 and a run of 12.
Find the square root of the result.
Roof is 6 12 pitch and measures at 2 400 square feet.
And for a roof with a slope of 6 12 that number 1 118 is your roof slope multiplier.
The pitch of the roof is the rise over a 12 inch run.
Get your roof size by using this roof pitch calculator.
Take the area of the roof s footprint say it s 5 000 square feet and multiply 5 000 by 1 118.
If the home measures 20 x 40 and has a 7 12 roof then to calculate the slope of the roof follow these steps.
Use our roof pitch calculator to find the pitch of your roof.
If your roof is flat or has no more than a 3 in 12 pitch you can calculate its total square footage by simply multiplying the length by the width.
Step 2 find the value of 7 12 from the roof slope multiplier table which is 1 16.
Roof pitch area multipliers.
Divide the rise by the run the run is 12.
The slope of the roof provides the rise and the run to be plugged into the equation.
And that s the number you were looking for.
The calculator cannot account for complex shapes based on a measurement of square footage alone.
That gives you 5 590 square feet which is the actual area of the surface of the roof.
2280 1900 380 feet added for pitch.
For example a 4 12 pitch roof that is 100 square feet.
1900 x 1 2 2280.
Steep roofs measure your house at ground level then add in the roof s overhang for greater accuracy.
If its pitch is 6 in 12 a pitch multiplier of 1 12 multiplying 1 152 sq ft 107 0 m 2 by 1 12 would give you an overall square footage of 1 290 square feet 120 m 2.
If your roof measures 48 feet 15 m x 24 feet 7 3 m multiplying its length by its width would give you a square footage of 1 152 square feet 107 0 m 2.
The total run is the distance from the peak to the edge of the roof which in this case is the total width divided in half which is equal to 10 feet or 120 inches.
So 2400 x 1 12 2 688 2 88 sqs added for pitch.
In cases where a roof has a complex shape such as in the image to the right measuring the dimensions and areas of each part of the roof to calculate total area will result in a more accurate measurement of area.
