Construction Purlin Flat Roof

They give added support to the roof and also provide a nailing surface for the end panels and drip edge.

Construction purlin flat roof.

The term plate means a major horizontal supporting timber. 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. These structural supports run perpendicular across the rafter beams.

Roof live load roof dead load x spacing x span of purlin 2. 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 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. Also known as sheeting rails purlins create the roofing members of the secondary framing of a steel building. By supporting the rafters they allow longer spans than the rafters alone. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top.

The purpose of purlins. 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 higher the snow load the closer the purlin spacing required. Purlin plates in wooden construction.