Directions for Using Table for the Steel Square.—Fig. 70-a.
Example.—Given a square hipped roof, that is, a roof with square corners, having a span of 25 ft. and a pitch of ½.
1. To Lay Out Miter Cut of Plate.—Take 12" on tongue of framing square and 12" on blade; scribe along blade. (Cf. small table, [Fig. 70-a].)
2. Length of Ridge.—Length of long plate diminished by length of short plate, increased by thickness of ridge piece plus diagonal thickness of hip.
3. To Lay Out Common Rafter.—
a. Plumb cut. (Cf. column 5, beginning at left, [Fig. 70-a].) Take 12" on tongue of square and 12" on blade (column 2), scribe along blade.
b. Length of common rafter. (Cf. column 11) 12½ (run of common rafter) x 16.97" (length of common rafter per foot of run) = 17' 8.12" = 17' 8⅛ (.12" = ⅛", columns 3 and 4).
c. Seat cut. (Cf. column 8) Take 12" on tongue and 12" on blade; scribe along tongue.
d. Tail for common rafter.
(1) Length determined as was that of common rafter, the horizontal projection or length of look- out becoming multiplier. 173