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.

Roof pitch multiplier.

Determine how many square feet of roof area a building has by measuring from the ground. Based on the pitch you can use the multiplier to determine the amount of material needed for a roofing project. This makes measuring easier knowing that you are able to get the exact measurement of roofs by merely standing on the ground. The roof pitch multiplier is the length of the hypotenuse divided by the run.

Repeat the run not the length of a common rafter. 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. 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. After safely measuring your roof to discover the pitch you can use the graph below to calculate your roof pitch in degrees and multiplier.

Now divide the rise by the multiplier to get the pitch eg. This roof pitch chart will give you your multiplier. Roof pitch multiplier c over b. A flat roof has a pitch of 1 meaning the material needed is 1 times the size of the roof.

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 pitch of this roof is 4 8 12. The calculator above can handle much of this math. Determine how many square feet of roof area a building has by measuring blueprints or plans.

48 10 4 8. The maths behind this number is that it is the square root of rise run 2 1. 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.

The chart gives a number of roof pitch multipliers for different roof slopes. The roof pitch multiplier is responsible for giving an accurate pitch measurement of the roof.