Johnson Level & Tool Mfg. RAS-1 - Manual (Page 20)

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and a miter allowance (using a 1 1/2" actual rafter thick-
ness) we get:
RAFTER LENGTH = 20 ' 3-7/8"
TAIL LENGTH = 2 ' 8-7/8"
BOTTOM PLUMB ALLOW. = 3-11/16"
MITER ALLOWANCE = 7/8"
LUMBER LENGTH = 23 ' 5-5/16"
NOTE: Only add miter allowances if they are used.
HIP RAFTER LAYOUT
STEP 1. TOP PLUMB CUT: The square is used in the same
manner as in Step 1 of the common rafter top plumb cut.
But now, read the Inch-Rise on the Hip-Val scale instead.
Remember that the top plumb cut is a bevel cut and that
opposite rafters will have opposite bevel cuts (see Figures
9 and 10). Therefore when placing the square on the rafter,
place it on the long side of the bevel (the bevel cut will be
explained in Step 4).
STEP 2. SEAT NOTCH: Measure the rafter length down
along the top of the rafter and make the seat plumb mark
in the same manner as you did for the common rafter (in
our example it is 20' 3-7/8"). Next, measure along the seat
plumb mark the seat depth and using the dashed line on
the square, draw a perpendicular line for the horizontal
seat mark (see Figure 10). Be sure all horizontal cuts for all
rafters are the same distance from the top edge of the raf-
ter at the wall line. For the proper fit of the hip rafter, cut
the top wall plate corner off (as shown in Figure 9). This
allows Hip seat notch to set in against a full flat corner,
rather than against an outside point.
STEP 3. TAIL OR BOTTOM PLUMB CUT: Measure down the
top of the hip rafter from the seat plumb mark and mark
the distance for the tail (in our example 2' 8-7/8"). Using
our square, make the bottom plumb mark. If a tail miter is