Purlin Spacing For Metal Roof Nz

Do all roofing projects require purlins.

Purlin spacing for metal roof nz. For 2x4s purlins the posts are spaced in 4 feet distance. For a fuller explanation of this refer to the nz metal roof and wall cladding code of practice. If the space between posts is greater than 8 feet then brace is needed to avoid buckling. 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.

By the standard the most used placement of purlin span for metal roof is five foot intervals. Two nails maybe preferred to prevent batten rolling over with high roof pitches. Rafters were birdsmouthed over the top plate and extended beyond the wall framing to create the eaves. Purlins typically 75 x 50 mm and fixed across the rafters were spaced at 760 900 mm centres depending on the roof cladding.

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. The purlin spacings should be limited to the lower of the trafficable limitations and design wind load with the capacity of the structure. For heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet. 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 2x6s purlins the posts are spaced in 6 feet distance. For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap. Purlins up to 1200mm spacing must be fixed with a 1 10g 80mm long purlin screw minimum or a pryda purlin strap bs 70. The typical spacing standards for residential and commercial buildings are about 1 to 2 foot.

This result should be referenced to the wind load span design graphs. We do recommend it however. 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. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.

Fastener patterns on nzs 3604 buildings should be consistent throughout the roof excluding top and bottom rows.