Performance-based building: lessons from implementation in New Zealand

New Zealand was an early adopter of a performance-based building code in 1992. The subsequent lessons learned from its implementation strategy are examined. Performance-based codes have decided advantages, but need careful implementation to capture these advantages. There are particular problems where the building code does not use specific numerical levels as the basis for mandatory performance requirements. A small fraction of houses built over the last decade developed ‘weathertightness' problems. The resulting media and political focus has led to a full review of the Building Act (the legislation leading to the Building Code) and new legislation will be in place by late 2004. As part of this, the Building Industry Authority will be absorbed into a government department. This will be followed by a detailed review of the New Zealand Building Code between 2005 and 2008. Although the performance requirements remain unaltered, the ‘Acceptable Solutions' that are deemed to satisfy the code have already been made more conservative and prescriptive to account for the lack of sufficient experience and understanding in some parts of the building industry. Other legislation is expected to address the asymmetry between the industry and its clients, including a builder licensing scheme and consumer protection systems. The key lesson is that implementation of performance-based building codes systems cannot simply be done by putting the documents before the industry. Successful introduction of performance-based building codes, and changes to them, must be accompanied by well-focused training programmes for all involved in the process, and especially the designers, the building control staff and the on-site workforce.