Roof Area Factor

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.

Roof area factor. Pitch of roof slope factor valley hip factor. For example suppose you have a 4 12 pitch roof and the width of the house is 28 feet. 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. You can consult the following chart to discover the slope factor and hip valley factor.

The slope factor works with metric and imperial measurements. For multi pitched roofs simply add the areas of all common pitches together by toggling layer visibility from the summed layer identified by the eye symbol at the left of the layers control. Now you re ready to price out the materials. Multiply the result by the factor and this is the length of the roof from base to ridge.

Multiply the square footage you calculated in step 1 by the pitch factor you determined in step 3. When outfitting your residential or commercial structure with products from everlast roofing it s important to know the incline or pitch of your roof. A roof s pitch is determined by how much it rises vertically for every foot it runs horizontally. 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.

If the area is 10 000 squares then roof pitch would be 12 500 10 000x1 25. To accurately calculate the area of your roof you must first determine its slope or pitch. Dividing the house width by two equals 14 feet. Download the slope chart pdf.

In our example the roof pitch was calculated as 9 12 which has a factor of 1 25 in the table. Looking at the chart the factor is 1 0541. Roof area in square metres length in metres width in metres slope factor roof area in square feet length in feet width in feet slope factor. That is if your tape reads 7 then add 1 that will give you 8 12.

Thus a moderate 6 in 12 roof pitch means that the roof rises 6 inches vertically for every 12 horizontal inches it runs. Then multiply the square footage with the roof pitch factor to get the total area of the roof. 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. The last step is to come off the ladder and simply multiply the factor determined in the step above with the number of total squares of the area.

For example the roof layer that protrudes above the roof is 1 so add 1 to your tape reading.