Issue 34 – December 2011
BRANZ has had a few calls about Note 5 in Tables 4.1 and 4.3 of NZS 3604:2011. Note 5 refers you to clause 4.4.4, which states that, for fastenings in contact with timber treated to H3.2 or higher with copper preservatives, use Tables 4.1 and 4.3 for your choice. This is because the clause sets a minimum type of fixing (304 stainless steel) for H3.2 or higher when the timber is treated with copper azole (CuAz) or alkaline copper quaternary (ACQ). So the choice it is directing you to is this:
- if the H3.2 treatment is CCA (copper chrome arsenate – hazard class 01 or 02), go back and make your choice from Table 4.1 or 4.3
- if the H3.2 treatment is CuAz (hazard class 58) or ACQ (hazard class 90), the default for fixings is 304 stainless steel in exposed or sheltered areas and hot-dip galvanised in all other locations.
For more information on cladding fixings, refer to Building Code compliance document E2/AS1 Tables 20 and 24.
Summarised from BRANZ Guideline November 2011.
- NZS 3604:2011 Timber-framed buildings