Building consent authorities (BCAs) are responsible for enforcing the building code and ensuring the durability and safety of buildings. Failing to comply with the building code can result in fines, delays, or even legal liabilities.
BCAs will request evidence of compliance with the performance requirements of Section B2 of the New Zealand Building Code (NZBC) when issuing a building consent. In broad terms, meeting the building code durability requirements can be achieved either through adhering to the minimum requirements of Clause B2 / Acceptable Solution 1 (B2/AS1) or through the development and provision of an Alternative Solution.
Compliance with Functional Requirements B2.2 Building Materials and Performance, B2.3.1 Building elements can be demonstrated via B2/AS1 acceptable solutions or B2/VM1.
Acceptable Solutions in accordance with Clause B2 can be achieved by conforming with the requirements of Standard NZS 3602 Part 1 (as modified by paragraph 3.2.2 of B2 Durability), NZS 3640 (as modified by paragraph 3.2.3 of B2 Durability) or through Standard NZS 3604 with reference to NZS 3602 (and NZS 3640).
In cases where durability demonstration is outside the scope of an Acceptable Solution, it may be possible to demonstrate compliance via verification method B2/VM1. Proof of performance under B2/VM1 through consideration of the expected in-service conditions includes service history, laboratory testing and comparable performance of similar buildings. If neither of the above is applicable to the building or parts of the building, an alternative compliance can be achieved by the means of an Alternative Solution. This includes evidence such as certification from a registered treatment provider, a building physics study, product labelling, or inspection reports. It is up to the Building Consent Authority (BCA) to request a peer review or to accept the evidence provided as sufficient to demonstrate compliance. A first, pre-application meeting is, therefore, often very helpful to discuss and agree upon the durability path of compliance and expectations of the BCAs.