RAFTERS are framing members that support a roof. They do for the roof what joists do for the floor and what the studs do for the wall. They are generally inclined members spaced from 16 to 48 in, apart that vary in size, depending on their length and the distance they are spaced.

The tops of the inclined rafters are fastened in one of the various common ways, which is determined by the type of roof. The bottoms of the rafters rest on the plate member, which provides a connecting link between the wall and the roof and is really a functional part of both.

The structural relationship between the rafters and the wall is the same in all types of roofs. The rafters are NOT framed into the plate, but simply nailed to it. Some are cut to fit the plate. In hasty construction, rafters are merely laid on top of the plate and nailed in place. Rafters may extend a short distance beyond the wall to form the eaves and protect the sides of the building. Figure 6-25 shows a typical roof framing plan. The following rafter terms and definitions supplement the notes in the drawing:

COMMON RAFTERSRafters that extend from the plates to the ridgeboard at right angles to both.

HIP RAFTERSRafters that extend diago-nally from the corners formed by perpendicular plates to the ridgeboard.

VALLEY RAFTERSRafters that extend from the plates to the ridgeboard along the lines where two roofs intersect.

HIP JACKSRafters whose lower ends rest on the plate and whose upper ends rest against the hip rafter.

VALLEY JACKSRafters whose lower ends rest against the valley rafters and whose upper ends rest against the ridgeboard.

CRIPPLE JACKSRafters that are nailed between hip and valley rafters.

JACK RAFTERS-Hip jacks, valley jacks, or cripple jacks.

TOP OR PLUMB CUTThe cut made at the end of the rafter to be placed against the

Figure 6-27.-Birds-mouth on a rafter with projection. 

ridgeboard or, if the ridgeboard is omitted, against the opposite rafters (fig. 6-25).