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