(6) The lengths that are given in the rafter table are line lengths. The overhang must be
(7) When the roof has an overhang, the rafter is usually cut square to save time. If the roof
does not have an overhang, the rafter is cut plumb, but no notch is cut in the rafter seat.
(8) A level cut is made on the rafter long enough to extend across the plate and the wall
sheathing. This type of rafter allows very little protection to the sidewalls.
3-12. Template Use. Rafter framing without the use
of ridgeboards may
be done rapidly
truss assembly jig or template. The template is laid out t form a pattern conforming to the exact
exterior dimensions of the truss. Lay out a template as follows (see Figure 3-31).
Figure 3-31. Laying out a template
a. Lay Out. Lay out a template as shown in Figure 3-31 and as follows:
(1) Measure and mark a straight line on a selected surface. Have the exact length of the
joists that will form the truss chord. This is baseline A (see Figure 3-31).
(2) From the center of the baseline and at right angles to it lay out the centerline (C) to form
the leg of a right triangle, the base of which is at half the length of baseline A, and the hypotenuse of
which (B) is the length of the rafter measured as indicated (see Figure 3-31).
(3) Nail 2- by 4- by 8-inch blocks flush with the ends of baseline A and centerline C as
shown in Figure 3-31. Mark the centerline on the center jig blocks.
b. Assembly. Assemble with a template as shown in Figure 3-31 and as follows: