One of several long, inclined, rectangular timbers used in the construction of pitched roofs, supporting the roof-covering, e.g. laths and tiles. Types of rafter include:angle rafter: principal rafter under the hip rafter carrying the purlins
on which the common rafters rest. In the USA any rafter at the angle of a roof, whether principal or not, hence either a hip- or jack-rafter in a valley;auxiliary rafter: in a truss
, a rafter used to stiffen the principal
by doubling it;binding rafter: purlin;common rafter: of uniform dimensions, placed at regular intervals along the sloping section of a roof, sometimes as intermediate members between principals. A pair of common rafters is a couple
;compass rafter: one curved on the lower side, or wholly curved, as in a truss;compound rafter: two rafters, one set over the other, separated by cleats, distance-pieces, or spacers, the inner rafters being secondary rafters
;hip rafter: one set diagonally at the hip of a roof where two slopes at 90° join, supporting the upper ends of the common rafters;jack-rafter: 1.
One set diagonally at the valley of a roof where two slopes join, such as at a dormer-window
roof, supporting the lower ends of common rafters. 2.
Shorter common rafter between wall-plate and hip-rafter, or between a valley and the ridge;principal rafter: large rectangular inclined timber in a sloping roof supporting a purlin and also serving as a common rafter. A principal rafter not
serving as a common rafter is a principal
;valley rafter: one set diagonally where two roofslopes meet in a valley, e.g. at a dormer-window, as in jack-rafter 1
;verge rafter: common rafter set beyond a gable
to support the roof-covering beyond the naked of the wall, itself supported on the ends of projecting wall-plates and purlins.
Alcock,, Barley,, Dixon,, & and Meeson (1996);
W. McKay (1957)