Roof Purlin Bracing

Structural design example four span metal building z purlin line supporting a standing seam roof.

Roof purlin bracing.

If you see braces which rest on ceiling joists look for a sag in the ceiling. Purlins 24 oc are typical along with the bottom bracing shown. Roof purlin needs no introduction to anyone in the construction industry. Like other frame members they are available with a galvanized finish and factory paint.

To strengthen the roof system truss clustering cross bracing and wind bracing is recommended at both end of the buildings and every 20 for longer span buildings. Cold formed steel bracing design using combinations of discrete and sheathing bracing and rp20 5. Roof decking is often also used as a diaphragm to transfer wind or seismic loads to the lateral bracing system below. Purlin plates in wooden construction.

Washington dc the american iron and steel institute aisi has published two new cold formed steel research reports. In their design life purlins are subjected to dead load e g self weight of sheeting materials and accessories live load e g. Wind and snow load. The decking is sized to resist the bending caused by these loads.

Purlin plates are beams which support the mid span of rafters and are supported by posts. The term plate means a major horizontal supporting timber. Larger joist framing materials for instance 2x10 or 2x12 s can be doubled or tripled up with plywood in between and glued to create a flush. Bracing must be installed off of walls or beams.

During maintenance services and repairs and environmental loads e g. Purlins brace the roof panels while girts brace the wall panels. Braces that rest on ceiling joists or which somehow pass the roof load to the ceiling below are defective installations. Corrugated metal deck and siding is used for roofs and walls respectively to span between purlins for roof loads or between girts for wind loads.

By supporting the rafters they allow longer spans than the rafters alone. Flange braces can also be very useful as an erection aid to align the purlins and eave struts. Truss clusters for maximum strength this image shows a cluster of three trusses tied together. Purlin bracing is an angle that connects the bottom flange of adjoining purlins to prevent purlin roll.

Zee purlin a roof structural is a horizontal structural member that supports the roof panels. Bracing purlin braces or any other roof braces ridge braces hip rafter bracing along with valley bracing must not be supported off the ceiling joists.