Fixing requirements update
Fixing at 600 mm centres maximum of top plates that support roofing members to studs, jack studs, and lintels.
Where rafters land on a top plate above a lintel, there are commonly short jack studs between the top of the lintel and the underside of the top plate. NZS 3604:2011 Timber-framed buildings has specific fixing requirements to the lintel and to the top plate for these jack studs to resist uplift depending on the:
- wind zone
- loaded dimension of the wall
- roof weight.
NZS 3604:2011 Table 8.18 requires:
- for light roofs in medium or higher wind zones, 2/90 x 3.15 mm end nails and 2 wire dogs, except where loaded dimension of wall is 2 metres or less, then nails only can be used in medium wind zones
- for light roofs in the low wind zone, 2 wire dogs are required where the loaded dimension is 5 metres or greater
- for heavy roofs in high and above wind zones, 2/90 x 3.15 mm end nails and 2 wire dogs, except where loaded dimension of wall is 2 metres or less, then nails only can be used in medium and high wind zones.
A 4.7 kN rated fixing system can be used instead of 2/90 x 3.15 mm end nails and 2 wire dogs and a 0.7 kN rated fixing instead of 2/90 x 3.15 mm end nails.
More detail on the fixings of rafters and top plates is given in the Build 131, To strap or not to strap?(external link)
Summarised from BRANZ Guideline, February 2014.