Roof Area Multiplier

This roof pitch chart will give you your multiplier.

Roof area multiplier.

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. Determine how many square feet of roof area a building has by measuring from the ground. Use our roof pitch calculator to find the pitch of your roof. The maths behind this number is that it is the square root of rise run 2 1.

Thus a moderate 6 in 12 roof pitch means that the roof rises 6 inches vertically for every 12 horizontal inches it runs. Take the area of the roof s footprint say it s 5 000 square feet and multiply 5 000 by 1 118. Take your area result and multiply it by the pitch multiplier or slope correction factor found in the table above to arrive at the roof s surface area. 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 s pitch is determined by how much it rises vertically for every foot it runs horizontally. And that s the number you were looking for. The roof pitch multiplier is responsible for giving an accurate pitch measurement of the roof. This is useful since the area of the roof itself is often difficult to measure by hand.

Next multiply the footprint of the roof by the multiplier below for your roof pitch to find the overall roof area. Determine how many square feet of roof area a building has by measuring blueprints or plans. Depending whether the roof area is measured horizontally possibly from a drawing or photograph a correction factor is necessary to determine the actual area of the roof. And for a roof with a slope of 6 12 that number 1 118 is your roof slope multiplier.

For example a 4 12 pitch roof that is 100 square feet. The pitch of the roof is the rise over a 12 inch run. Given pitch and a horizontal area measurement multiply the horizontal area by a correction factor corresponding to pitch provided in the table below to determine the actual area of the roof to be used in the roofing material calculator. That gives you 5 590 square feet which is the actual area of the surface of the roof.

To accurately calculate the area of your roof you must first determine its slope or pitch. Now you re ready to price out the materials. Simply multiply this number by the area covered by a sloped roof to obtain the total surface area of the roof itself. This makes measuring easier knowing that you are able to get the exact measurement of roofs by merely standing on the ground.