How To Figure Roof Rafters

Use a framing square to mark a plumb cut as close to the end of the board as possible.

How to figure roof rafters.

Each common rafter span is calculated by subtracting the thickness of the ridge from the total span then dividing the answer by two. I prefer using the right hand. 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. Determine the pitch of the roof which is the angle that rafters rise from the outside walls to the ridge.

Rafter length using pitch v r 2 sqrt 1 p 2 where v overhang r roof span p pitch. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length. Roof pitch calculator. You might need a long tape measure to get the span then.

Determine the direction the rafters rise from opposite outside walls to the ridge. Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement. Refer to the. Total span ridge 2 individual rafter span.

Typically this is shown on. Laying out a calculated rafter place the board on a set of sawhorses with the crown away from you. 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. The other thing you ll need is the roof pitch angle.

Includes result for hip valley factor slope factor and the roof slope in degrees.