Roof Pitch Multiplier

The chart gives a number of roof pitch multipliers for different roof slopes.

Roof pitch multiplier. 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. Based on the pitch you can use the multiplier to determine the amount of material needed for a roofing project. The roof pitch multiplier is responsible for giving an accurate pitch measurement of the roof. Now divide the rise by the multiplier to get the pitch eg.

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. The calculator above can handle much of this math. 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. This makes measuring easier knowing that you are able to get the exact measurement of roofs by merely standing on the ground.

The maths behind this number is that it is the square root of rise run 2 1. Repeat the run not the length of a common rafter. Also see the roof pitch multiplier table the hip and valley factor is a number that is multiplied by the actual run horizontal distance of a common rafter to determine the length of a hip or valley rafter. Determine how many square feet of roof area a building has by measuring blueprints or plans.

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. A flat roof has a pitch of 1 meaning the material needed is 1 times the size of the roof. 48 10 4 8. The pitch of this roof is 4 8 12.

After safely measuring your roof to discover the pitch you can use the graph below to calculate your roof pitch in degrees and multiplier. The roof pitch multiplier is the length of the hypotenuse divided by the run. Roof pitch multiplier c over b. And for a roof with a slope of 6 12 that number 1 118 is your roof slope multiplier.

Take the area of the roof s footprint say it s 5 000 square feet and multiply 5 000 by 1 118. 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.