Construction Purlin Flat Roof

Roof live load roof dead load x spacing x span of purlin 2.

Construction purlin flat roof.

Metal roof purlins are installed horizontally under metal roofs. They give added support to the roof and also provide a nailing surface for the end panels and drip edge. The higher the snow load the closer the purlin spacing required. 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.

The term plate means a major horizontal supporting timber. Purlin plates are beams which support the mid span of rafters and are supported by posts. Purlins are 2 by 4 feet and are installed much like metal roofing. The purpose of purlins.

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. Purlin plates in wooden construction. A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin. Or less x 1 1 cfu the flat use factor for applying the load to the wide face of a member.

These structural supports run perpendicular across the rafter beams. 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 common 4 on center design is suitable for snow loads up to 60 for most applications.