figure 2-16. Where the jack rafter, hip, or valley

rafter requires side cuts, the cut is given in the table

(fig. 2-16). The other type of table (fig. 2-17) gives

the actual length of rafter for a given pitch and span.

same number of steps as there are feet in the run,

appears on the face of the blade. It is used to

which leaves 4 inches over a foot. This 4 inches is

determine the length of the common, valley, hip and

taken care of in the same manner as the full foot run;

jack rafters, and the angles at which they must be cut

that is, with the square at the last step position, make

to fit at ridge and plate. To use the table the

a mark on the rafters at the 4-inch mark on the blade,

carpenter must become familiar with it and know

then move the square along the rafter until the tongue

what each figure represents. The row of figures in

rests at the 4-inch mark (1, fig. 2-15). With the

the first line represents the length of common or main

square held for the same cut as before, make a mark

rafters per foot of run, as the title indicates at the left-

along the tongue. This is the line length of the rafter.

hand end of the blade. Each set of figures under each

The seat cut and overhang are made as described in **a**

inch division mark represents the length of rafter per

above (2, 3, 4, fig. 2-15). When laying off rafters by

foot of run with a rise corresponding to the number of

any method, be sure to recheck the work carefully.

inches over the number. For example, under the 16-

When two rafters have been cut, it is best to put them

inch mark appears the number 20.00 inches. This

in place to see if they fit. Minor adjustments may be

number equals the length of a rafter with a run of 12

made at this time without serious damage or waste of

inches and a rise or 16 inches, or, under the 13-inch

material.

mark appears the number 17.69 inches which is the

The

rafter length for a 12-inch run and a 13-inch rise.

framing square may have one or two types of rafter

The other five lines of figures in the table will not be

tables on the blade. Figures 2-16 and 2-17 are

discussed as they are seldom used in the theater of

illustrations of the two types. One type gives both

operations.

the line length of any common rafter per foot of run

and the line length of any hip or valley rafter per foot

rafters, the width of the building must be

of run. The difference in length of the jack rafter

spaced 16 to 24 inches OC (on center) is also shown

in

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