Purlin Spacing For Steel Roofing

Fyi we run purlins on 3 5 feet on center depending on size of purlin.

Purlin spacing for steel roofing.

Dead load will be the actual weight of the roof steel and the roof purlins. For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap. Purlin spacing for metal roofing. We do recommend it however.

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. Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry. The typical spacing standards for residential and commercial buildings are about 1 to 2 foot. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.

For heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet. This will depend upon the type of panel that is used and the thickness of the steel. Screw line spacing for metal roofing over metal purlins. If the space between posts is greater than 8 feet then brace is needed to avoid buckling.

Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load. The heavier the expected load is the shorter the distance between the purlins. For 2x6s purlins the posts are spaced in 6 feet distance. 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.

For 2x4s purlins the posts are spaced in 4 feet distance. An engineer will use a load chart in order to determine the spacing between metal purlins. The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. 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.

Once the purlin spacing is determined then the metal roofing panels are typically attached to every line of purlins. Do all roofing projects require purlins. Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig.