Divide the rise by the run the run is 12.
Roof slope multiplier table.
Step 3 multiply step 1 and step 2 i e.
Find the square root of the result.
Low slope roofs are from 0 to 3 12 in pitch.
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.
And for a roof with a slope of 6 12 that number 1 118 is your roof slope multiplier.
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.
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.
Also see our page quick reference.
The following table shows how the same common roof slopes can be expressed using rise in run ratios degrees and percentages.
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.
It s just a little math.
If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks.
This is useful since the area of the roof itself is often difficult to measure by hand.
For example if you measure 4 inches the pitch of your roof is 4 12.
If the home measures 20 x 40 and has a 7 12 roof then to calculate the slope of the roof follow these steps.
Some sources consider low slope to include 3 12 pitch roofs.
Roof pitch refers to the measurement of the slope of a roof and you express this as a ratio.
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.
Notes to the table above.
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.
Take the area of the roof s footprint say it s 5 000 square feet and multiply 5 000 by 1 118.
The roof pitch multiplier is a number that allows you to find the total surface area of your roof.
Understanding the roof pitch chart process.
Degrees to roof pitch rise in run to see a table.
That gives you 5 590 square feet which is the actual area of the surface of the roof.
Typically the steeper the roof is the higher the price will be.
Step 1 multiply 20 and 40 which equals 800.
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.
Simply multiply this number by the area covered by a sloped roof to obtain the total surface area of the roof itself.
This will give you the rise over run or pitch.
Step 2 find the value of 7 12 from the roof slope multiplier table which is 1 16.
