Roof Slope Multiplier Table

Notes to the table above.

Roof slope multiplier table.

Find the square root of the result. Although there s isn t any standard pitch of a roof used on all kinds of sloped roofs you can determine the range of pitches by using a roof angle calculator and by considering factors like the local climate and roofing materials. If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks. Also see our page quick reference.

This will give you the rise over run or pitch. Low slope roofs are from 0 to 3 12 in pitch. For example if you measure 4 inches the pitch of your roof is 4 12. Step 2 find the value of 7 12 from the roof slope multiplier table which is 1 16.

Some sources consider low slope to include 3 12 pitch roofs. This is useful since the area of the roof itself is often difficult to measure by hand. If the home measures 20 x 40 and has a 7 12 roof then to calculate the slope of the roof follow these steps. Roof pitch refers to the measurement of the slope of a roof and you express this as a ratio.

Simply multiply this number by the area covered by a sloped roof to obtain the total surface area of the roof itself. Degrees to roof pitch rise in run to see a table. The following table shows how the same common roof slopes can be expressed using rise in run ratios degrees and percentages. It s just a little math.

The first thing that you need to understand before picking any selections from a roof pitch multiplier chart is to ensure that it s affordable. For any roof slope expressed as x in 12 rise in run the hip and valley factor is determined by finding the square root of rise run 2. 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.

Typically the steeper the roof is the higher the price will be. 800 multiplied by 1 16. 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. Take the area of the roof s footprint say it s 5 000 square feet and multiply 5 000 by 1 118.

Divide the rise by the run the run is 12. The roof pitch multiplier is a number that allows you to find the total surface area of your roof. Step 3 multiply step 1 and step 2 i e. That gives you 5 590 square feet which is the actual area of the surface of the roof.

See below after the table for directions on how to convert any roof slope from one form to another even roof slopes not shown in the table. The hip and valley factor varies according to the slope of the roof as shown in the table below. Simply locate a roof rafter board place the end of the level against the bottom edge and measure from the 12 inch mark vertically to the bottom edge of the rafter.