Figure 2-21.-Step-off method for calculating common rafter length.
Step 1. Lay out the rafter line length. Hold the
the center line of the roof. From either end
framing square with the tongue in your
right hand, the blade in the left, and the
heel away from your body. Place the
square as near the right end of the rafter
as possible with the unit of rise on the
tongue and the unit of run on the blade
along the edge of the rafter stock. Strike a
plumb mark along the tongue on the wide
part of the material. This mark represents
of this mark, measure the line length of the
rafter and mark the edge of the rafter
stock. Hold the framing square in the same
manner with the 6 on the tongue on the
mark just made and the 12 on the blade
along the edge. Strike a line along the
tongue, his mark represents the plumb
cut of the heel.
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