Report: Pathways to Building Code compliance for farm-totara timber
Sustainable Forest Solutions
New Zealand Building Code
The author wishes to acknowledge the support from the organisations and individuals that have enabled this project to be undertaken. These include; the Ministry for Primary Industries (through the Sustainable Farming Fund), Tane’s Tree Trust and the New Zealand Farm-Forestry Association, (including the Indigenous Forestry Section), the Northland Totara Working Group members Paul Quinlan and David Bergin for assistance in finalising this report, Michael Hayes & Geoff Cookson, for their time and donated sample boards of timber for testing, and saw-miller, Shane Hyde, for his time and the use of his band-saw in re-sizing some of the timber samples. The time and input from Robin Curtis, CEO of NZ Sustainable Forest Products, is also acknowledged and much appreciated.
In producing this report, reasonable care has been taken regarding the accuracy of the information presented. However, no guarantee as to the truth, accuracy or validity of any of the comments, implications, recommendations, findings or conclusions are made by the author, the Northland Totara Working Group, Tane’s Tree Trust, or any other party. Therefore, neither the authors, nor any of the supporting organisations, shall not be liable for, or accept any responsibility for, any loss, damage or liability incurred as a result of direct or indirect result of any reliance by any person upon information or opinions or recommendations expressed in this work. Users of any of this information, whether contained or inferred, in or arising from this report do so at their own risk.
The Building Code contains compulsory rules for all new building work and sets out performance criteria that building work must meet.
The Building Code does not prescribe how work should be done, but states how completed building work and its parts must perform. An advantage of a performance-based Building Code is flexibility - it contains no prescriptive requirements stipulating that certain products or designs must be used. This flexibility offers opportunities for developments and innovation in building design, technology and systems. However, demonstration of adequate performance of building materials in specific applications is required, either by providing evidence of compliance (such as durability performance), or by using Standards that offer code-compliant materials or methods.
Compliance with the Building Code can be demonstrated using various pathways. Some pathways must be accepted by the building consent authority as meeting the performance requirements of the Building Code.
Clause B1: Structure
Performance requirements around loads that buildings are subject to is set by Building Code clause B1 Structure, to ensure buildings are stable and withstand physical conditions.
Clause B2: Durability
The durability requirements for structural timber used in buildings are provided in clause 2 of the New Zealand building code.
Hazard classes relate to the level of chemical treatment required under the building code.
Douglas fir and durability
Untreated Douglas fir (including sapwood) is allowed for structural applications under the New Zealand Building Code under certain circumstances.