The answer is the number of roofing squares for the roof.
How to figure square feet of a roof.
Multiply the square footage of your roof by 1 to get the 10 percent waste allowance.
The calculator cannot account for complex shapes based on a measurement of square footage alone.
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.
To conclude the example if your total roofing area is 17 300 square feet your waste allowance would be 17 300 x 1 1 730 square feet.
Because each 100 square feet of roof is one roofing square divide the total area from step 1 by 100.
Convert the area to roofing squares.
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 amount of roofing material you need is 17 300 1 730 19 030 square feet.
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.
Steep roofs measure your house at ground level then add in the roof s overhang for greater accuracy.