How To Figure Roof Rafters

Roof pitch calculator.

How to figure roof rafters.

Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. Refer to the. Use a framing square to mark a plumb cut as close to the end of the board as possible. Includes result for hip valley factor slope factor and the roof slope in degrees.

Each common rafter span is calculated by subtracting the thickness of the ridge from the total span then dividing the answer by two. Rafter length using pitch v r 2 sqrt 1 p 2 where v overhang r roof span p pitch. 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.

You might need a long tape measure to get the span then. Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement. Typically this is shown on. Hook the long point with a tape measure stretch it out past the length and make.

I prefer using the right hand. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length. Total span ridge 2 individual rafter span. The other thing you ll need is the roof pitch angle.

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