Issue 36 – March 2012
Engineers who are specifying screw gauges for structural applications need to be aware of shank diameter differences that occur for a given gauge. For example, for a 10 gauge screw shank, the diameter can range from 2.74 mm to 5.12 mm. The former would only equate to a 4 gauge screw using Table 4.5 in NZS 3603:1993 Timber structures Standard, which requires a 10 gauge screw to have a minimum shank size of 4.88 mm.
BRANZ suggest that, when specifying, it would be safer to state the minimum shank diameter rather than specifying the gauge.
- NZS 3603:1993 Timber structures Standard