Roof Area Multiplier

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.

Roof area multiplier.

To accurately calculate the area of your roof you must first determine its slope or pitch. The roof pitch multiplier is responsible for giving an accurate pitch measurement of the roof. And for a roof with a slope of 6 12 that number 1 118 is your roof slope multiplier. Now you re ready to price out the materials.

A roof s pitch is determined by how much it rises vertically for every foot it runs horizontally. Next multiply the footprint of the roof by the multiplier below for your roof pitch to find the overall roof area. 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 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.

Determine how many square feet of roof area a building has by measuring blueprints or plans. Determine how many square feet of roof area a building has by measuring from the ground. This is useful since the area of the roof itself is often difficult to measure by hand. For example a 4 12 pitch roof that is 100 square feet.

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. This makes measuring easier knowing that you are able to get the exact measurement of roofs by merely standing on the ground. This roof pitch chart will give you your multiplier. Or just enter your numbers into this roof pitch degrees.

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. That gives you 5 590 square feet which is the actual area of the surface of the 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.

Simply multiply this number by the area covered by a sloped roof to obtain the total surface area of the roof itself. The pitch of the roof is the rise over a 12 inch run. The roof pitch multiplier is a number that allows you to find the total surface area of your roof. And that s the number you were looking for.