Metal Roof Purlin Spacing Standards

If the space between posts is greater than 8 feet then brace is needed to avoid buckling.

Metal roof purlin spacing standards.

For normal deliveries nominal lengths should not exceed 12000mm. 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. Standard gage are generally used for roofing.

Purlin spacing for metal roofing. For minimum lengths and lengths over 12000mm contact your nearest lysaght office. The typical roof structure now consists of steel i beam rafters placed approximately 10 feet this varies depending on purlin size and other variables apart with either 4 6 or 8 lightweight steel purlins installed horizontally across the rafters. Fyi we run purlins on 3 5 feet on center depending on size of purlin.

A 2ʺ nominal lumber thickness or 1ʺ nominal thickness are both acceptable purlins. When channels are used the ridge purlin is placed as close to the peak of the truss as possible in order to shorten the connection to the purlin on the opposite side of the centerline see figure 2. Lengths greater than 12000mm require special transportation and on site handling facilities. When using purlins fabral recommends a maximum spacing of 24 on center note that 5v requires solid decking.

Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig. The spacing of purlins on roofs and girts on wall is usually 4 to 6 ft. For 2x6s purlins the posts are spaced in 6 feet distance. Lysaght purlins are available custom cut in any transportable length however there are some limitations.

Pullout values decrease if the fasteners protrude completely through the purlins. Kiln dried softwood is recommended for purlins or decking pine fir hemlock and spruce. However it is important to note that expected load is a crucial factor while determining this. 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.

We do recommend it however. Although the standard spacing of roof trusses may be the same as that of rafters with 24 inch spacing being a common option the design of a truss may allow for the use of a lower grade of lumber than would be required for rafters with comparable spacing and span. Numbers 20 and 22 u s. For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap.

Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry. Metal roofs and pole buildings. The typical spacing standards for residential and commercial buildings are about 1 to 2 foot.