In our December 2022 Notes, we advised that the NZS 3603:1993 Timber Structures Standard had been superseded by NZS AS 1720.1 Timber structures - Design methods. We noted however that the superseded NZS 3603 is still currently cited in:
- NZBC B1/VM1 for any particular timber building or building design subject to modifications detailed in the verification method and in conjunction with AS/NZS 1170.
- NZBC B1/VM4 which states that timber piles shall comply with NZS 3605 or NZS 3603
This month we have updated 75 sections to add additional guidance notes directly into the sections on this topic. In brief we retain reference to NZS 3603 where appropriate, but alert subscribers to NZS AS 1720.1 as a proposed alternative solution design option.
There is a significant shift in format between the two standards and content changes that designers need to be aware of if considering the use of NZS AS 1720.1, including:
- Changes to connections
- Additional mechanical properties provided for relevant New Zealand timber species
- Methods for designing timber buildings to resist earthquake loading
- Increased guidance on the design of structural timber diaphragms
- Properties and methods for designing with laminated veneer lumber (LVL)
- Potential options to reduce a projects carbon footprint.
For a more detailed commentary on the changes refer to BRANZ Build 189 article
https://www.buildmagazine.org.nz/index.php/articles/show/new-timber-design-standard