Construction Purlin Flat Roof

These structural supports run perpendicular across the rafter beams.

Construction purlin flat roof.

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. The purpose of purlins. A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin.

The term plate means a major horizontal supporting timber. Also known as sheeting rails purlins create the roofing members of the secondary framing of a steel building. Roof live load roof dead load x spacing x span of purlin 2. The higher the snow load the closer the purlin spacing required.

Or less x 1 1 cfu the flat use factor for applying the load to the wide face of a member. The common 4 on center design is suitable for snow loads up to 60 for most applications. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. They give added support to the roof and also provide a nailing surface for the end panels and drip edge.

Purlins are an important component in a pre engineered steel structural kit. 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. Metal building roof purlins provide three structural functions.