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.

And for a roof with a slope of 6 12 that number 1 118 is your roof slope 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. The calculator above can handle much of this math. 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.

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. Now divide the rise by the multiplier to get the pitch eg. The roof pitch multiplier is the length of the hypotenuse divided by the run.

The roof pitch multiplier is responsible for giving an accurate pitch measurement of the roof. 48 10 4 8. Repeat the run not the length of a common rafter. Determine how many square feet of roof area a building has by measuring from the ground.

The pitch of this roof is 4 8 12. If you know the pitch of a roof you can use the numbers in the following pitch table to do the following. This roof pitch chart will give you your multiplier. 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. 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. The maths behind this number is that it is the square root of rise run 2 1.

The chart gives a number of roof pitch multipliers for different roof slopes. Based on the pitch you can use the multiplier to determine the amount of material needed for a roofing project.