Roof Pitch Multiplier

This roof pitch chart will give you your multiplier.

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

The chart gives a number of roof pitch multipliers for different roof slopes. The calculator above can handle much of this math. Roof pitch multiplier c over b. The maths behind this number is that it is the square root of rise run 2 1.

Now divide the rise by the multiplier to get the pitch eg. If you know the pitch of a roof you can use the numbers in the following pitch table to do the following. This makes measuring easier knowing that you are able to get the exact measurement of roofs by merely standing on the ground. Determine how many square feet of roof area a building has by measuring from the ground.

The roof pitch multiplier is the length of the hypotenuse divided by the run. 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. Repeat the run not the length of a common rafter. 48 10 4 8.

Determine how many square feet of roof area a building has by measuring blueprints or plans. Based on the pitch you can use the multiplier to determine the amount of material needed for a roofing project. 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. And for a roof with a slope of 6 12 that number 1 118 is your roof slope multiplier.

The roof pitch multiplier is responsible for giving an accurate pitch measurement of the roof. A flat roof has a pitch of 1 meaning the material needed is 1 times the size of the roof.