Report on the Review of the Building Code: 4 The New Zealand Building Code

4.1 Building codes - an overview

Building codes are used in most developed countries to limit the likelihood of undesirable or unacceptable outcomes for people in buildings. They cannot eliminate risk, but provide a means of limiting risk.

Some undesirable events are natural and cannot be controlled - for example, natural hazards like earthquakes and storms. Codes provide rules to make sure buildings can cope with such hazards, and to limit damage so that people in them are safe in all but the most severe event. Codes are also intended to prevent some undesirable events happening in the first place - for example, the spread of diseases or illness because of poor sanitation.

Building codes have traditionally been important for the safety and health of people in buildings. In some countries they are also a means to address other issues such as energy efficiency, environmental protection, economic growth and social outcomes. This is true in New Zealand, where the purpose of the Act requires the Building Code to address wellbeing and sustainable development, as well as the safety and health of people.

4.2 New Zealand Building Code

The New Zealand Building Code was first written in 1991 as part of the implementation of the now-repealed Building Act 1991. That Act was enacted in response to a 1990 report by the Building Industry Commission. The Commission was set up in 1986 by government to 'determine within a suitable framework … the most appropriate legal and regulatory provisions for buildings and building construction and maintenance consistent with the public interest (including health, safety and amenity aspects)'.

The establishment of the Building Industry Commission arose from widespread dissatisfaction with New Zealand's lack of a coherent regime of building controls. There was a view that local building control regimes administered by individual councils should be replaced by a more unified, nationally applicable set of standards.

These standards, including the Building Code, were embodied in the Building Act 1991, which has since been replaced by the Building Act 2004. The 2004 Act led to the Department of Building and Housing taking over the functions of the Building Industry Authority, which was disestablished.

4.3 How the Building Code works

The New Zealand Building Code defines the functional requirements and performance criteria for buildings to provide basic protection for the people who use them, and to achieve national or social goals such as energy efficiency and access for people with disabilities.

The Building Code applies to the construction of all new buildings and to alterations or renovations to existing buildings.

'Buildings' include housing, community facilities, commercial and industrial structures, outbuildings, and structures such as bridges, platforms and dams.

The standards set out in the Building Code balance quality, cost, affordability and accessibility.

To allow flexibility and to encourage innovation, the Building Code is performance-based rather than prescriptive - that is, it specifies the requirements for building work through functional requirements (describing the required outcomes) and performance requirements (the level to which those outcomes are to be achieved). It does not prescribe how buildings are to be constructed.

The Building Code is fundamental to the operation of a building sector that:

• delivers buildings and homes that perform well in the New Zealand environment and contribute to sustainability
• delivers homes and buildings that meet the changing needs of New Zealanders and contribute to strong, effective communities
• is strong and well-performing with skilled building and housing professionals
• ensures building and home owners, tenants and users are confident and value well-designed, well-built, warm, safe and healthy homes and buildings.

Other key elements in the building system include:

• a well-functioning building industry, including skilled building professionals such as designers, architects, builders, tradespeople and manufacturers, and informed consumers
• a sound legal framework for conducting business so all parties can be held accountable for their actions
• reliable standards, testing and design guides for materials and processes used in construction
• warranties and insurance to provide reassurance to building owners
• education and training to provide knowledge and skills to those involved in the building process.

Diagram1: Documents that supportthe Building Code

Diagram 1 shows how the Building Code fits into the building system. The Building Code is supported by Compliance Documents, which may be:

• Verification Methods (tests and calculation methods by which a design may be evaluated for compliance with the Building Code), and/or
• Acceptable Solutions (a prescriptive, low 'transaction' cost means of complying with the Building Code).

Buildings built using the method described in a Compliance Document are automatically deemed to comply with the Code. They are sometimes referred to as 'cookbook' solutions, because they prescribe a 'recipe' for ensuring compliance.

Alternative ways of building, known as alternative solutions, may be used if it can be shown that they meet the performance requirements set out in the Building Code.

New Zealand or Australian Standards and other publications may be cited in the Acceptable Solutions and Verification Methods, and may also be cited as part of an alternative solution.

Compliance Documents are an integral part of the building system and must be aligned with the Building Code for the system to be effective. They are widely used by the sector for a large proportion of the building work designed and undertaken.

The Building Code sets a stake in the ground for the wider building controls system. It directly provides the framework for the sector's intellectual knowledge contained in Compliance Documents, Standards and other guidance information. It also sets up the innovation framework for research and product development to efficiently deliver cost-effective solutions to building users.