How To Figure The Length Of A Roof Rafter

1 1543 x 1 610 1 858m.

How to figure the length of a roof rafter.

This gives you a rise of 10 feet 120 inches and a run of 12 feet 144 inches. Includes result for hip valley factor slope factor and the roof slope in degrees. Rafter length 6 38 ft. Rise 6 ft.

Hook the long point with a tape measure stretch it. C b cosθ 6 cos20 6 38 ft. For example if the ridge beam is 1 5 inches thick subtract 3 4 of an inch from the overall rafter length. This is called a 10 inch pitch.

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. Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. I prefer using the right hand side of the board for this. So the rafter lengths 1 86m long easy.

Typically this is shown on the roof construction plan. Determine the direction the rafters rise from opposite outside walls to the ridge. Given length of roof 30 ft. For every 12 inches of run the roof will rise 10 inches.

B adjacent rise. Angle 20 we know sinθ opposite hypotenuse. In the above triangle a opposite run. Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement.

Place the board on a set of sawhorses with the crown away from you. This means that for every 1m the rafter travels horizontally the angled length of the roof will be 1 1543m. Use a framing square to mark a plumb cut as close to the end of the board as possible. Calculate rafter length using angle.

If you are calculating rafter length from the center of the ridge beam as shown below you will need to subtract half of the thickness of the ridge beam from the top end of the rafter. Cosθ adjacent hypotenuse b c. How to calculate rafter lengths. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length.

All we do now is use a calculator to multiply 1 610 by the measurement in the book. Laying out a calculated rafter. Determine the pitch of the roof which is the angle that rafters rise from the outside walls to the ridge. Let s assume you have a structure that is 24 feet wide and you would like to build a roof that is 10 feet high.