The shape of cee purlins does not allow end lapping they are butted together.
Purlins shed roof.
Purlins are an important component in a pre engineered steel structural kit.
Also known as sheeting rails purlins create the roofing members of the secondary framing of a steel building.
In architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof.
Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load.
Purlins and girts are used longitudinally to support the roof sheeting which they were originally designed for.
They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top.
Welded together they can be used as columns braces and ties.
In a structural steel shed the main portal frames and roof rafters are made from strong steel sections which are welded together and later bolted together.
They give added support to the roof and also provide a nailing surface for the end panels and drip edge.
The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed.
The purpose of purlins.
Purlins are 2 by 4 feet and are installed much like metal roofing.
Metal roof purlins are installed horizontally under metal roofs.
These structural supports run perpendicular across the rafter beams.