Durability Requirements in the Building Code

There is no doubt about the importance of durability in construction, but in recent years the durability requirements of the New Zealand Building Code (the Code) appear to have caused some confusion which has the potential to lead to errors being made when assessing compliance with various requirements of the Building Act 2004 and the Code.

Building Code Requirements in Relation to Durability

Clause B2 (Durability) of the Code essentially amounts to a requirement that the building will continue to satisfy the various performance requirements of the Code throughout its life. Critically, compliance with Clause B2 is linked to performance in relation to other Code clauses. This is reflected in the Code as follows:

  • Clause B2.1 (objective): “The objective of this provision is to ensure that a building will throughout its life continue to satisfy the other objectives of this code” (emphasis added).
  • Clause B2.2 (functional requirement): “Building materials, components and construction methods shall be sufficiently durable to ensure that the building, without reconstruction or major renovation, satisfies the other functional requirements of the code throughout the life of the building(emphasis added).
  • Clause B2.3.1 (performance): “Building elements must, with only normal maintenance, continue to satisfy the performance requirements of this code for the lesser of the specified intended life of the building or…” (emphasis added).

When read together it is evident that there cannot be a breach of Clause B2 without a breach of some other code clause (for example, Clause E2 (External Moisture)). Clause B2 simply puts a timeframe on the performance expectations.

Recent observations suggest that the durability performance requirements can be a source of confusion, with people often asserting breaches of Clause B2 without a linked failure of another building code clause that shows the building element or component is not satisfying the performance requirements of the Code. For the purposes of assessing compliance with the Code, describing a building element as ‘lacking durability’ does not actually establish a breach of the Code.

As an example, damage to an area of cladding is not in itself a breach of the Code unless it lets in water resulting in undue dampness or damage to building elements (or results in non-compliance with some other code clause). Unless there is a breach of another functional requirement of the Building Code it remains an aesthetic issue only.

In the context of building related disputes, this is something which experts giving evidence should be mindful of. Any misunderstanding of the application of the Code could be tested in cross-examination or could be reflected in a judgment. Given the overlap of the legal and technical aspects of disputes in this context, this is an area where collaboration between the legal and expert teams becomes critical.

Timeframes Associated with Clause B2 (Durability)

Clause B2.3.1 sets out the relevant minimum timeframes for which various building elements should perform. Additional information regarding the expected life of various elements is set out in Table 1 of B2/AS1. For example, Table 1 sets out that wall claddings which contribute to the structural performance of a building must perform for the life of the building being not less than 50 years, while non-structural wall claddings must perform for not less than 15 years.

Clause B2 in the context of Building Consent Requirements

The importance of a correct interpretation of Clause B2 becomes apparent in the context of the requirements to obtain a Building Consent. Schedule 1 of the Building Act sets out Exempted Work for which a Building Consent is not required, and importantly states that the following work is not Exempted Building work, such that a building consent will be required:

Clause 1(3)(c): “repair or replacement (other than maintenance) of a building product or an assembly incorporated in or associated with a building that has failed to satisfy the provisions of the building code for durability, for example, through a failure to comply with the external moisture requirements of the building code…”

In the context of building failures, the question of whether a building consent is required is therefore directly linked to the performance requirements of Clause B2 (Durability). Owners, consultants and contractors undertaking repair works will need to understand the link between Clause B2 and the other code clauses when assessing whether a Building Consent is required.

The question of whether a Building Consent is required is both a legal and technical question. From a technical point of view, we are able to advise owners, consultants or contractors who have questions about whether there has been a failure to meet durability requirements or other code clauses. We are also able to recommend lawyers with expertise in this area if necessary.

If you would like to discuss any of the above, please feel free to reach out to us.

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