Cripple Rafters. - In finding the length of the cripple rafters of a rectangular roof, in which a hip and the valley rafters are parallel, as at p, Fig. 80, the run equals the projection in the plan of the house as at r. The rafters at s are cripples, as they have a cheek cut upon each end; all of those between h and k are the same, as they do not rest upon the plate. Their length may be ascertained by shortening either or both ends the distance of J1 starting from a rafter of known length, as described in the previous problem.

There is no seat cut to a cripple rafter, but instead a plumb, or ridge cut, or a cheek cut may be made at one or both ends. The cheek cuts may be found by the method used upon the jack and hip rafters.

In nailing the cripple rafters to their places, they should be raised until their top edges are in line with the center of the valley rafter against which they are fitted, as the sheeting should be cut to that point. In nailing the jacks and cripples, be sure that the hips and valleys are nailed perfectly straight, and not sprung sideways.