Attic Truss Purlins

Rafter boards are fastened to the ridge board at the peak and the top plate where they join the wall.

Attic truss purlins.

By supporting the rafters they allow longer spans than the rafters alone. A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin. Purlin plates are beams which support the mid span of rafters and are supported by posts. The roof truss structure and design is integral to roof structural integrity and shape.

We provide angle iron steel trusses in gable lean to and header styles. 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. Purlin plates in wooden construction. There are many types of roof trusses as wall as many types of roofs more types than there are parts.

In finished space insulation is placed between the rafter boards and drywall or other material is fastened to the face. 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. 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.

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. 2 on center trusses with 8 on center posts are even stronger designs. Truss clusters for maximum strength this image shows a cluster of three trusses tied together. The economic spacing of trusses means the spacing at which the overall cost of trusses purlins roof cover columns etc.

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. Purlins 24 oc are typical along with the bottom bracing shown. Pre welded purlin cups predrilled bolt holes and included mounting hardware for fast easy installation. Steel trusses offer increased strength faster installation and a longer life compared to wood frame pole barn trusses.

For small spacing of trusses while the purlins become light and less costly the trusses will work out to be costly. Rafters have a tendency to flatten under gravity thrusting outwards on the walls.