How To Figure Roof Rafters

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.

How to figure roof rafters.

Typically this is shown on. How to calculate rafter lengths step 1. Use a framing square to mark a plumb cut as close to the end of the board as possible. Rafter length using pitch v r 2 sqrt 1 p 2 where v overhang r roof span p pitch.

I prefer using the right hand. Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. Refer to the. Determine the direction the rafters rise from opposite outside walls to the ridge.

Roof pitch calculator. Determine the pitch of the roof which is the angle that rafters rise from the outside walls to the ridge. Total span ridge 2 individual rafter span. Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement.

Use our online rafter length calculator to quickly compute the length of the shed roof rafter by entering the measurements of overhead length of roof span pitch or angle. Laying out a calculated rafter place the board on a set of sawhorses with the crown away from you. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length. You might need a long tape measure to get the span then.

Each common rafter span is calculated by subtracting the thickness of the ridge from the total span then dividing the answer by two.