Fifteen years of performance-based design in New Zealand
The paper gives an overview of performance-based design in New Zealand with particular reference to fire, seismic, and durability design of timber structures. The performance-based code came into force 15 years ago when it superseded the previous prescriptive codes. Major changes were introduced, particularly in fire engineering, where every specific limitation, such as that on the maximum number of storeys for timber buildings, was removed. The compliance of each design with the performance requirements may be demonstrated using either of an approved verification method (specified calculations), an acceptable solution (prescriptive requirements), or an alternative solution (special oneoff design). This new regime allowed more freedom in design and the use of new construction systems, but with the simultaneous deregulation of the building industry, a reduction in quality followed, with poor details and sloppy construction leading to a number of problems such as “leaky buildings”. For this reason, more stringent regulations were recently introduced, with a much more rigorous system of quality control.