The head of a T-iron or L-iron strut is usually secured to the rafter by flat strips or ears of iron placed on each side of the web of the strut, and riveted through that of the rafter (see Fig. 383, and Fig. 411, Plate VI.) The end of the web of the strut may be cut off obliquely to fit the under side of tl»e rafter.

The foot of the strut is secured to the tie rod by a bolt passing through the end of the table, which is turned up, and then secured with a double nut, as in Fig. 383a. Washers, W W of a bevelled section, are required in order that the nut may communicate an even pressure to the flange of the strut.

Both the head and the foot of a strut may be very simply connected by the use of flat plates as in Figs. 419, 423, Plate VII.

Cast-iron struts of a cross-shaped section are sometimes used, their upper ends being formed with jaws to seize the web of the principal rafter.

Purlins, properly so called, for carrying common rafters, are seldom used in small iron roofs.

Small purlins, or horizontal rafters, which themselves directly support the boarding or roof covering, are however in common use.