Construction Purlin Flat Roof

The higher the snow load the closer the purlin spacing required.

Construction purlin flat roof.

They give added support to the roof and also provide a nailing surface for the end panels and drip edge. The common 4 on center design is suitable for snow loads up to 60 for most applications. A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin. Purlin plates in wooden construction.

These structural supports run perpendicular across the rafter beams. The term plate means a major horizontal supporting timber. Or less x 1 1 cfu the flat use factor for applying the load to the wide face of a member. 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.

Purlins are an important component in a pre engineered steel structural kit. Roof live load roof dead load x spacing x span of purlin 2. Too high a snow load means the purlins fail regardless of how close together you put them because a 2 4 or 2 6 flat can only span a certain distance between trusses as snow loads increase. Metal roof purlins are installed horizontally under metal roofs.

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. Metal building roof purlins provide three structural functions. Purlins are 2 by 4 feet and are installed much like metal roofing.