Figure 3-10. Rafter method
The level cut or width of the seat is the width of the plate, measured perpendicular to
the plumb cut, as shown in step 4. Using the try square, square the lines down on
the sides from all level and plumb-cut lines. Now the rafter is to be cut (see step 5).
(3) Step-Off Method. The rafter length of any building may be determined by "stepping it
off" by successive steps with the square, as follows:
Step off the same number of steps as there are feet in the run. For example, if a
building is 20 feet 8 inches wide, the run of the rafter would be 4 inches over 10 feet.
Figure 3-11, page 3-8, illustrates the four steps of the step-off method.
This 4 inches is taken care of in the same manner as the full-foot run; that is, with
the square at the last step position, make a mark on the rafters at the 4-inch mark
(see Figure 3-11, step 1).
With the square held for the same cut as before, make a mark along the tongue.
This is the line length of the rafter. The seat cut and hangover are made as described
above and shown in Figure 3-11, steps 2, 3, and 4.