Formula Roof Pitch Multiplier

Measure the rise of your roof.

Formula roof pitch multiplier. Here are the equations you may use to solve for the length of the slope and the rafter. Steep roofs measure your house at ground level then add in the roof s overhang for greater accuracy. The formula for the roof pitch multiplier comes from the famous pythagorean theorem. Now you re ready to price out the materials.

Step 2 find the value of 7 12 from the roof slope multiplier table which is 1 16. 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. 48 10 4 8. Use our roof pitch calculator to find the pitch of your roof.

Now divide the rise by the multiplier to get the pitch eg. Roof pitch degree table. Calculate the roof pitch as the proportion of rise and run. 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.

Now solving for c in the equation above gives. Step 1 multiply 20 and 40 which equals 800. Next multiply the footprint of the roof by the multiplier below for your roof pitch to find the overall roof area. Where a is the rise of the roof b is the run of the roof and c is the rafter hypotenuse of the triangle with side lengths a and b.

The pitch of this roof is 4 8 12. The calculator above can handle much of this math. Pitch rise run 1 5 6 25. Let s say it is equal to 1 5 m.

800 multiplied by 1 16. Use the following formula which also describes a right triangle. 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. Image 1 12 to 12 12 roof pitch 7 12 pitch.

If your roof is flat or has no more than a 3 in 12 pitch you can calculate its total square footage by simply multiplying the length by the width. Calculate the rafter length substituting these values into the following formula. 100 1 054 105 4ft2. Rafter rise run this formula is from the pythagorean theorem.

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. If the home measures 20 x 40 and has a 7 12 roof then to calculate the slope of the roof follow these steps. Rafter rise run 1 5 6 2 25 36 38 25rafter 38 25 6 18 m.