Purlin Spacing For Metal Roof Nz

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.

Purlin spacing for metal roof nz.

Purlins typically 75 x 50 mm and fixed across the rafters were spaced at 760 900 mm centres depending on the roof cladding. Purlins up to 1200mm spacing must be fixed with a 1 10g 80mm long purlin screw minimum or a pryda purlin strap bs 70. Fastener patterns on nzs 3604 buildings should be consistent throughout the roof excluding top and bottom rows. This result should be referenced to the wind load span design graphs.

Rafters were birdsmouthed over the top plate and extended beyond the wall framing to create the eaves. For 2x4s purlins the posts are spaced in 4 feet distance. Two nails maybe preferred to prevent batten rolling over with high roof pitches. For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap.

For 2x6s purlins the posts are spaced in 6 feet distance. For a fuller explanation of this refer to the nz metal roof and wall cladding code of practice. 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 heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet.

Ridge boards were 25 mm 1 wide with a depth dependent on the rafter size. Do all roofing projects require purlins. 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. 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.

The typical spacing standards for residential and commercial buildings are about 1 to 2 foot. By the standard the most used placement of purlin span for metal roof is five foot intervals. We do recommend it however. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.

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