Steel Roof Purlin Spacing

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.

Steel roof purlin spacing.

Dead load will be the actual weight of the roof steel and the roof purlins. Metal building roof purlins provide three structural functions. Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load. Engineered purlin metal mart offers a complete line of engineered purlin material.

Once the purlin spacing is determined then the metal roofing panels are typically attached to every line of purlins. Available in cee or zee shape red oxide primed or galvanized 16 14 or 12 gauge sizes from 4 up to 12 flange widths of 1 1 2 up to 4 cut to your specified lengths hole punching available load tables available for all material. The wider the roofing panels the greater spacing distance you should put. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.

Purlins are non pressure treated 1 x 4 x 12 lumber that is installed on to the roof in a specific layout pattern and screw pattern. Secondly purlins tie the rafters together stabilizing and strengthening the structure s rigid framing. Also known as sheeting rails purlins create the roofing members of the secondary framing of a steel building. Do all roofing projects require purlins.

Purlin spacing for metal roofing the country inspector upon approving the plans seems to have written in per manufacturers specs regarding 2x4 purlins on 16 centers. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. First the purlins support the roof. There is a chance of damaging roofing sheets if you are failed to do so.

The metal roof purlins spacing must be done correctly within narrow tolerances. 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. We do recommend it however. They give added support to the roof and also provide a nailing surface for the end panels and drip edge.

The width of metal panels will determine the rafter spacing. The building was built 24 on center. Purlins are 2 by 4 feet and are installed much like metal roofing. Metal roof purlins are installed horizontally under metal roofs.

Screw line spacing for metal roofing over metal purlins. An engineer will use a load chart in order to determine the spacing between metal purlins. This will depend upon the type of panel that is used and the thickness of the steel.