Sag Rod In Roof Truss

More sag rods means more support along the span of the purlin which helps greatly in slenderness and deflection.

Sag rod in roof truss.

In diameter with lines spaced approximately six to right feet apart. Usually trusses are put 24 inches apart. As each truss is put up on top of opposite walls it must be put up straight and supported while the next truss is put up. Compute the corresponding flexural moments for no sag rod layout middle sag rod layout and along thirds sag rod layout.

The purlin spacing angle of roof truss spacing length of truss yield strength f. A common collapse mechanism in a steel framed building fire is when a steel floor truss or steel beam is heated from below. Temporarily screw a 3 foot 2x4 to the bottom of the sagging truss so that the 4 inch side of the 2x4 is flat against the bottom of the truss and in the center of the sag. These are round bar threaded at their ends parallel to the roof slope and secured to the purlin webs with nuts often at their mid points or one third points of their.

To hold them up until the decking of the roof is placed on top a 12 foot 1 inch by 4 inch piece of lumber is used. Place a screw jack found at any hardware store between the 2x8 on the floor of your attic and the sagging truss where the 2x4 is attached. If sufficiently heated it will lose its stiffness and start to sag. Typical sag rods are 5 8 in.

It is given to decrease the deflection of the bottom chord member. Key in a roof hasp 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.