Attic Truss Purlins

This article and series of illustrated diagrams shows you all the parts of a basic roof truss king truss and queen truss.

Attic truss purlins.

A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin. By supporting the rafters they allow longer spans than the rafters alone. Rafter boards are fastened to the ridge board at the peak and the top plate where they join the wall. The roof truss structure and design is integral to roof structural integrity and shape.

Purlin plates in wooden construction. Purlins 24 oc are typical along with the bottom bracing shown. The term plate means a major horizontal supporting timber. 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.

Purlin plates are beams which support the mid span of rafters and are supported by posts. Truss clusters for maximum strength this image shows a cluster of three trusses tied together. The boards creating the slope of the roof are wider than lumber used to build trusses 2x8s 2x10s and 2x12s are most common in rafters vs. In timber construction purlins are nailed to the rafter or supporting trusses while in steel roof construction they are welded or bolted to the rafters or trusses by the means of cleats.

We provide angle iron steel trusses in gable lean to and header styles. 2 on center trusses with 8 on center posts are even stronger designs. The economic spacing of trusses means the spacing at which the overall cost of trusses purlins roof cover columns etc. For small spacing of trusses while the purlins become light and less costly the trusses will work out to be costly.

Pre welded purlin cups predrilled bolt holes and included mounting hardware for fast easy installation. With a 2 on center truss spacing 7 16 osb or plywood sheathing can be used to strengthen the structure replacing purlins provide excellent sound deadening when it rains or hails and simplifies walking around on the roof especially higher pitched roofs. For large spacing of trusses purlins will work out to be heavy and costly. Rafters have a tendency to flatten under gravity thrusting outwards on the walls.

Roof purlin are members used to directly support roof sheeting materials and could be made of timber or steel. A timber roof truss is a structural framework of timbers designed to bridge the space above a room and to provide support for a roof trusses usually occur at regular intervals linked by longitudinal timbers such as purlins the space between each truss is known as a bay.