Roof Purlin Bracing

Purlin plates are beams which support the mid span of rafters and are supported by posts.

Roof purlin bracing.

Roof decking is often also used as a diaphragm to transfer wind or seismic loads to the lateral bracing system below. Truss clusters for maximum strength this image shows a cluster of three trusses tied together. Purlins 24 oc are typical along with the bottom bracing shown. The term plate means a major horizontal supporting timber.

Bracing must be installed off of walls or beams. The decking is sized to resist the bending caused by these loads. Cold formed steel bracing design using combinations of discrete and sheathing bracing and rp20 5. Structural design example four span metal building z purlin line supporting a standing seam roof.

Purlin plates in wooden construction. Flange braces can also be very useful as an erection aid to align the purlins and eave struts. If you see braces which rest on ceiling joists look for a sag in the ceiling. Like other frame members they are available with a galvanized finish and factory paint.

A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin. 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. Purlins brace the roof panels while girts brace the wall panels. Roof purlin needs no introduction to anyone in the construction industry.

Wind and snow load. Purlin bracing is an angle that connects the bottom flange of adjoining purlins to prevent purlin roll. By supporting the rafters they allow longer spans than the rafters alone. In their design life purlins are subjected to dead load e g self weight of sheeting materials and accessories live load e g.

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. Zee purlin a roof structural is a horizontal structural member that supports the roof panels. Washington dc the american iron and steel institute aisi has published two new cold formed steel research reports. They provide lateral bracing to the compression flanges of the primary frame members to increase frame capacity.

During maintenance services and repairs and environmental loads e g. The bottoms of purlin braces should rest on top of a bearing wall.