Purlin Roof Framing

Purlin plate principal purlin and common purlin.

Purlin roof framing.

The roof support system is a ridgepole and either rafters which run perpendicular from the top of the walls to the ridge or purlins which run parallel to the ridge. The wider the roofing panels the greater spacing distance you should put. Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load. 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.

The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. Metal building roof purlins provide three structural functions. The purlins of a roof support the weight of the roof deck. Purlins are supported either by rafters or the walls of the building.

There is a chance of damaging roofing sheets if you are failed to do so. First the purlins support the roof. 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. Welded together they can be used as columns braces and ties.

They are most commonly used in metal buildings though they sometimes replace closely spaced rafters in wood frame structures. They are made from 16 ga 0 060 min 50 ksi structural grade g 90 galvanized steel and specifically notched to fit over the ribs of the existing metal roof panels. The purpose of purlins. The metal roof purlins spacing must be done correctly within narrow tolerances.

Secondly purlins tie the rafters together stabilizing and strengthening the structure s rigid framing. In traditional timber framing there are three basic types of purlin. You have to allow some overlap section on each side of. A common arrangement is a rafter and purlin system which combines purlins and rafters.

Roof hugger retrofit sub purlins are zee shaped structural members that are typically 10 to 12 feet in length.