Now solving for c in the equation above gives.
Roof rafter multiplier.
The next option in table 10 1 is 3 3 m.
If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length.
Remember practice makes perfect.
The hip and valley factor is a number that is multiplied by the actual run horizontal distance of a common rafter to determine the length of a hip or valley rafter.
This exceeds the rafter span proposed without using the multiplier so is suitable.
Let s say it is equal to 1 5 m.
This indicates a 190 45 mm rafter size.
Students should use the sin cos and tan funtion rather then the multiplier table to calculate the length of the roof members.
Use the following formula which also describes a right triangle.
Rafter rise run this formula is from the pythagorean theorem.
You can also calculate roof pitch even without using a roof slope calculator.
Step 5 rafter size.
Calculate the roof pitch as the proportion of rise and run.
It takes some time to get use to these functions.
Rafter rise run 1 5 6 2 25 36 38 25rafter 38 25 6 18 m.
The formula for the roof pitch multiplier comes from the famous pythagorean theorem.
If the home measures 20 x 40 and has a 7 12 roof then to calculate the slope of the roof follow these steps.
Find the value of 7 12 from the roof slope multiplier table which is 1 16.
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.
And for a roof with a slope of 6 12 that number 1 118 is your roof slope multiplier.
800 multiplied by 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.
Includes result for hip valley factor slope factor and the roof slope in degrees.
Measure the rise of your roof.
Pitch rise run 1 5 6 25.
This table provides the hip and valley factor for common roof pitches as well as the underlying equation for the factor.
Multiply 20 and 40 which equals 800.
A roof pitch of 4 in 12 4 12 has a rise of 4 and a run of 12.
That gives you 5 590 square feet which is the actual area of the surface of the roof.
Calculate the rafter length substituting these values into the following formula.
Divide the rise by the run the run is 12.
2 5 1 1 multiplier 2 75 m does not give the required span of 3 000 m.
The slope of the roof provides the rise and the run to be plugged into the equation.
Find the square root of the result.
Here are the equations you may use to solve for the length of the slope and the rafter.
Take the area of the roof s footprint say it s 5 000 square feet and multiply 5 000 by 1 118.
Read the rafter size in the left column of table 10 1 for the 3 3 m span chosen.
Multiply step 1 and step 2 i e.
