Roof Pitch Rafter Length

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.

Roof pitch rafter length.

For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2. You can also calculate roof pitch even without using a roof slope calculator. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length. For example a roof that rises 6 inches for every 12 inches of horizontal run has a 6 12 pitch.

Select the following information by using the drop downs to enter values in feet and inches. Pitch is the incline of the roof represented as the ratio of rise to the span twice the run. Includes result for hip valley factor slope factor and the roof slope in degrees. The rafter member will be longer.

Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. For example if the roof rises 4 feet and the span is 16 feet twice the run then the pitch is 4 16 or 1 4. Our roof rafter calculator tools are handy for calculating the number of rafters needed rafter length calculator lineal feet of rafter board feed in ridge and sub facia and the total board feet in the roof. Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement.

It can be assessed in two ways either as the angle the rafter makes with the horizontal or the proportion between the rise and the run of the roof. There is no standard universal pitch of roof. They have a pitch ranging from 4 12 to 9 12. Select a roof pitch.

Use the blueprints to establish a pitch for the roof. The angle or pitch of a roof is calculated by the number of inches it rises vertically for every 12 inches it extends horizontally. The length of the rafter is given from the long point of the ridge cut at the top down along the top edge the board to the same plumb cut on the rafter s notch. Roof pitch is often expressed as a ratio between rise and run in the form of x 12.

High pitched roofs often need extra fasteners and their pitch can be as high as 21 12. Determine a thickness for the ridge and use the drop down to select it. It is the length of this portion of the rafter. Rafter length using angle v r 2cos a rafter length using pitch v r 2 sqrt 1 p 2 where v overhang r roof span p pitch.

The hip roof framing calculator returns the value of the main rafter the side rafter the length of the hip the height of the knee wall and the lengths of the jack rafters. If you plan to have overhang etc. Note that this is not the actual length of the rafter. The pitch of a roof is its vertical rise over its horizontal span.

Conventional roofs are the easiest to construct and you can walk on them safely.