Construction Purlin Flat Roof

These structural supports run perpendicular across the rafter beams.

Construction purlin flat roof.

The term plate means a major horizontal supporting timber. The common 4 on center design is suitable for snow loads up to 60 for most applications. 8 x section modulus of a 4 2 of 1 3125 x fb fiberstress in bending x 1 15 duration of load x 1 15 cr repetitive member factor as the purlins are spaced 24 o c. Or less x 1 1 cfu the flat use factor for applying the load to the wide face of a member.

Metal building roof purlins provide three structural functions. Roof live load roof dead load x spacing x span of purlin 2. Purlin plates in wooden construction. Metal roof purlins are installed horizontally under metal roofs.

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. Purlins are 2 by 4 feet and are installed much like metal roofing. Also known as sheeting rails purlins create the roofing members of the secondary framing of a steel building.

Purlin plates are beams which support the mid span of rafters and are supported by posts. They give added support to the roof and also provide a nailing surface for the end panels and drip edge. The purpose of purlins. The higher the snow load the closer the purlin spacing required.