Sag Rod Pronunciation a rod for preventing the sagging of an open-web steel joist that is used as a purlin with its depth at right angles to a roof slope.

Sag Rods as Lateral Supports for Girts and Purlins. Z‐sections are commonly used as girts and purlins. In many installations, sag rods are used to provide alignment for these members for the attachment of the steel panels and to reduce their tendency to bend laterally and twist.

First, install the sag rods that connect the two purlins at the ridge of the building. Each rod must be attached from the' top hole of one purlin through the bottom hole of the adjacent purlin. Use two nuts at each end of the sag rods-one on each side of each purlin.