Calculate the rafter length substituting these values into the following formula.
Roof pitch tables metric.
Calculate the length of a rafter in metres using the roof slope measured in degrees and the gable wall width in metres.
In essence a roof pitch chart is provided as a rough guide usually by a roofing company to help you see what the average roof pitches tend to be.
Drag sliders to animate the results and diagram.
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.
You can also calculate roof pitch even without using a roof slope calculator.
Roof pitch calculator results explained slope the slope of a roof is represented as x 12 where x is the number of inches in rise for every 12 inches of run.
They have a pitch ranging from 4 12 to 9 12.
High pitched roofs often need extra fasteners and their pitch can be as high as 21 12.
Rafter length from roof slope in degrees using metric measurement.
Rafter rise run 1 5 6 2 25 36 38 25rafter 38 25 6 18 m.
Measure the rise of your roof.
Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run.
We included a roof pitch chart below the 7 12 example image and the calculator below that.
On blue prints architects engineers usually display the pitch of a roof in the format shown on the image where number 4 represents a rise and number 12 represents a length.
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.
Image 1 12 to 12 12 roof pitch 7 12 pitch.
Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch.
Roof pitch and corresponding angles.
Pitch rise run 1 5 6 25.
Let s say it is equal to 1 5 m.
Enter run the flat level length then click pitch angle or rise to select then enter other known dimension angle or pitch.
If there is an overhang the rafter overhang is measured in millimetres from outside wall to inside fascia board level across.
This means if a roof rises 4 in the length of 12 your roof pitch would be 4 12 or 18 43 degrees.
If this isn t practical then perform the same measurement on the underside of the roof.
Calculate the roof pitch as the proportion of rise and run.
Usually they come in the form of a roof pitch diagram chart but other times it will be presented to you in a conversion format.
Use the following formula which also describes a right triangle.
The triangle diagram will be re drawn to scale with all dimensions marked.
