Purlin Spacing For Metal Roofing Nz

When the purlin spacing is close to the maximum allowable for the profile and ease of curvature the roof cladding is more likely to be damaged by foot traffic and distortion between the purlins.

Purlin spacing for metal roofing nz.

For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Roof bracing hipped roof construction does not require additional bracing but gabled roofs require both roof plane and roof space bracing. Fastener patterns on nzs 3604 buildings should be consistent throughout the roof excluding top and bottom rows.

For heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet. Metalcraft roofing s structural division manufactures metalcraft super span shortened to mss purlins and girts for the new zealand construction market and the pre engineered garages and sheds market segment. It should be noted that timber purlins for metal roof cladding are minimum 70mm x 45mm h1 2 18 moisture content and that battens used previously for tiles must not be used. The adjustable cleat can be rotated up to 15 degrees from normal to accommodate the change in angle from vertical portal to the roof slope of the rafter.

For a fuller explanation of this refer to the nz metal roof and wall cladding code of practice. The purlin spacings should be limited to the lower of the trafficable limitations and design wind load with the capacity of the structure. New zealand metal roofing manufacturers inc. Purlins typically 75 x 50 mm and fixed across the rafters were spaced at 760 900 mm centres depending on the roof cladding.

It often depends on the wideness thickness and the types of roofing materials the climate it has to withstand and many other factors. April 2012 nz metal roof and wall cladding code of practice table of contents v 2 2 page 3 table of contents 1 1 0 table of contents 2 0p erformance 3 0 construction load 4 0 d esign 5 0f lashings 6 0p enetrations 7 0i nstallation 8 0 roof drainage 9 0 plastic roof lighting 10 0 pressed metal tiles. This result should be referenced to the wind load span design graphs. Do all roofing projects require purlins.

Mss purlins and girts are available in a variety of sizes and gauges cut to length and prepunched to suit a variety of applications. When the radius of curvature is close to the minimum the purlin spacing should be reduced to the end span distance for each gauge and profile. If a design quotes wind speed in m s ask for a roof plan showing design loads and purlin spacing apply serviceability loads for pierce fastened products ultimate loads for clip fastened profiles.