Roof Rafter Span Lengths

Input the rafter span on the flat eave overhang and pitch of the roof.

Roof rafter span lengths.

Marking out the roof rafter lengths onto the timber before cutting step 1. Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall. With the tape measure hooked onto the top end transfer your two rafter lengths onto. For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2.

Roof rise this should be calculated from the base of the roof to the highest point of the roof gable the peak. Mark the plumb cuts. Rafter length using angle v r 2cos a rafter length using pitch v r 2 sqrt 1 p 2 where v overhang r roof span p pitch. Rafter run outer wall this should be measured starting from the center of the roof span and then extending to the very edge of the exterior wall.

Ceiling joist span use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size. Before you can mark the rafter lengths and layout check the. Determine the camber along the timbers length. Area span on the flat please enter area span on the flat in foot.

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. Click the button to calculate the stock size needed for this job.