These rods are generally formed with a fork at the upper end, so as to embrace the web of the principal rafter, to which they are secured by a bolt.
The lower ends of the rods pass through a hole in the tie rod, and terminate in a screw carrying a nut, by screwing up which the tie rod may be raised and the truss set up.
Fig. 385. a cross thus - or of two channel irons similarl united.
Very efficient struts are formed by flat or angle irons kept apart by distance pieces, varying in length so as to form a tapering beam. Such a strut with one distance piece for a small roof is shown in Figs. 396, 397, Plate IV., a longer one with three distance pieces in Fig. 437, Plate IX.