Metal Roofing Purlin Spacing Nz

Purlins up to 1200mm spacing must be fixed with a 1 10g 80mm long purlin screw minimum or a pryda purlin strap bs 70.

Metal roofing purlin spacing nz.

They are a breather type material consisting of bitumen saturated heavyweight kraft paper or fire retardant solvent free laminated two layers reinforced heavyweight kraft paper coated with a water based water repellent. 1 2 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. For heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet. 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.

This result should be referenced to the wind load span design graphs. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. 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. Where the end purlin spacing is less than 800mm an adjustable end brace with a bolted end cleat is available as twisting of the end cleat is not practical.

For a fuller explanation of this refer to the nz metal roof and wall cladding code of practice. 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. Ridge boards were 25 mm 1 wide with a depth dependent on the rafter size. 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.

Do all roofing projects require purlins. For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap. The purlin spacings should be limited to the lower of the trafficable limitations and design wind load with the capacity of the structure. Purlin batten purlin batten fixing type d 3 45kn 2 blue screws or 2 skew nails plus 2 wire dogs for purlin on edge fixing type c 2 4kn purlin batten 1 blue screw 2 nails fixing type b 0 8kn purlin batten fixing type a 0 55kn 1 nail purlin batten note.

Self supporting roofing underlays designed to span between purlins where the purlin spacing is not more than 1200 mm. We do recommend it however. 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.

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