Parts of a Rafter

Parts of a Rafter

"This figure shows the cuts for a common rafter and the sections formed. The ridge cut allows the upper end to fit tightly against the ridge. The bird's-mouth is formed by a seat cut and plumb (vertical) cut when the rafter extends beyond the plate. When there is no overhang, the bottom of the rafter is terminated by a seat cut and a plumb cut that extends upwards."

from Modern Carpentry by Willis H. Wagner; 1976