How To Figure Roof Rafters

Determine the pitch of the roof which is the angle that rafters rise from the outside walls to the ridge.

How to figure roof rafters.

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. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length. Typically this is shown on.

Includes result for hip valley factor slope factor and the roof slope in degrees. Roof pitch calculator. Refer to the. You might need a long tape measure to get the span then.

How to calculate rafter lengths step 1. Rafter length using pitch v r 2 sqrt 1 p 2 where v overhang r roof span p pitch. 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. 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. 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. Hook the long point with a tape measure stretch it out past the length and make. I prefer using the right hand.

Laying out a calculated rafter place the board on a set of sawhorses with the crown away from you.