Purlins On A Roof

In the past the majority of roof structures were of wooden construction but over the past 15 to 20 years there has been.

Purlins on a roof.

The purpose of purlins. Purlins are non pressure treated 1 x 4 x 12 lumber that is installed on to the roof in a specific layout pattern and screw pattern. The wider the roofing panels the greater spacing distance you should put. The roof deck is the wood panel ply board or metal sheeting that creates the surface of the roof.

The roof support system is a ridgepole and either rafters which run perpendicular from the top of the walls to the ridge or purlins which run parallel to the ridge. A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. Purlins are an important component in a pre engineered steel structural kit.

In structural steel or aluminum construction p urlins usually w shapes or channels transfer roof loads to the major structural elements supporting the roof. Purlins traditionally support the roof deck cladding sheeting and are in turn supported by the principal rafters steel beams etc. The purlins of a roof support the weight of the roof deck. The term plate means a major horizontal supporting timber.

Purlins are 2 by 4 feet and are installed much like metal roofing. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Also known as sheeting rails purlins create the roofing members of the secondary framing of a steel building. Metal building roof purlins provide three structural functions.

The width of metal panels will determine the rafter spacing. They give added support to the roof and also provide a nailing surface for the end panels and drip edge. These structural supports run perpendicular across the rafter beams. Metal roof purlins are installed horizontally under metal roofs.

Purlin plates are beams which support the mid span of rafters and are supported by posts. Purlin plates in wooden construction. A traditional purlin strictly by definition is a horizontal structural member in a roof. The type and spacing of purlins is a design consideration which depends upon the incident roof loads as well as the limiting lengths of sheeting to be used.

The metal roof purlins spacing must be done correctly within narrow tolerances. By supporting the rafters they allow longer spans than the rafters alone.