How To Figure Roof Rafters

The other thing you ll need is the roof pitch angle.

How to figure roof rafters.

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. 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.

Determine the pitch of the roof which is the angle that rafters rise from the outside walls to the ridge. Typically this is shown on. Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement. How to calculate rafter lengths step 1.

Roof pitch calculator. 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. Use a framing square to mark a plumb cut as close to the end of the board as possible. Total span ridge 2 individual rafter span.

Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length. Hook the long point with a tape measure stretch it out past the length and make. Determine the direction the rafters rise from opposite outside walls to the ridge.

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