Roof Framing Purlin

Hip roofs have hip rafters which are oriented diagonally to the ridge and outside walls.

Roof framing purlin.

Purlins support the loads from the roof deck or sheathing and are supported by the principal rafters and or the building walls steel beams etc. The purpose of purlins. Purlins are not required or needed unless rafters are overspanned and then the purlins serve as support to prevent roof sag deflection due to the overspanned and or undersized rafters. In architecture structural engineering or building a purlin or historically purline purloyne purling perling is any longitudinal horizontal structural member in a roof except a type of framing with what is called a crown plate.

Welded together they can be used as columns braces and ties. These structural supports run perpendicular across the rafter beams. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. Purlins are 2 by 4 feet and are installed much like metal roofing.

Hips rest on an outside corner at the bottom and connect to. 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. The cos of the purlin spacing is because the load on the purlins is vertical and the purlin spacing is with the run of the roof.

Stabilization typically involves installation of a purlin system. For sake of discussion we will assume a minimal roof snow load of 20 psf pounds per square foot and a 4 12 roof slope. They give added support to the roof and also provide a nailing surface for the end panels and drip edge. Cee purlins are secondary steel framing members most commonly used as roof purlins wall girts and header jamb and sill for windows and doors on metal buildings.

Hip rafters are simply called hips and are shown here as brown. The shape of cee purlins does not allow end lapping they are butted together. Purlins are installed horizontally under metal roofs. Dead load will be the actual weight of the roof steel and the roof purlins.

A common arrangement is a rafter and purlin system which combines purlins and rafters.