What is the performance-based Building Code

The BCA is described as a performance-based standard.

When the BCA was first prepared the advantages of a performance-based BCA were seen as allowing cost savings in building construction by:

  • permitting the use of alternative materials, forms of construction or designs to meet the prescriptive requirements;
  • the innovative use of materials, forms of construction or designs;
  • permitting designs to be tailored to a particular building;
  • giving clear information on what the BCA is trying to achieve; and
  • allowing the designer flexibility in the use of materials, forms of construction or design, provided that the intent of the BCA is met (in other words, allow for flexibility provided the performance required by the BCA is met), while still allowing acceptable existing building practices through the deemed-to-satisfy provisions.

Hierarchy of the performance-based BCA

The performance-based BCA was drafted following consideration of numerous overseas models (including the New Zealand, British, Swedish and Dutch examples) to suit the Australian building regulatory environment. This has meant that the performance-based BCA substantially includes the technical requirements from the previous BCA90, with a ‘performance hierarchy’ built around them.

The structure and hierarchy of the operative provisions of the BCA are shown below:

The following is an explanation of the terms used and how they operate in practice.

At Level 1 are the 'objectives'. These represent the reason the community wants a matter regulated. They are primarily expressed in general terms, and usually refer to the need to safeguard people and protect adjoining buildings or other property. An example of an objective from the BCA is: ‘the objective is to safeguard the occupants from injury or loss of amenity caused by inadequate height of a room or space.’

At Level 2 are the 'functional statements'. These set out in general terms how a building could be expected to satisfy the objectives (or community expectations). An example of a functional statement from the BCA is: ‘A building is to be constructed to provide height in a room or space suitable for the intended use.’

At Level 3 are the 'performance requirements'. These outline a suitable level of performance which must be met by building materials, components, design factors, and construction methods in order for a building to meet the relevant functional statements, and in turn, the relevant objectives. The performance requirements are the core of the BCA and are the only parts of the code with which compliance is mandatory. An example of a performance requirement in the BCA is: ‘a room or space must be of a height that does not unduly interfere with its intended function.’

Level 4 are the 'building solutions'. These set out the means of achieving compliance with the performance requirements. The BCA provides for two methods that can be followed to develop a building solution.

At Level 4a are the 'deemed-to-satisfy provisions'. These include examples of materials, components, design factors, and construction methods which, if used, will result in compliance with the performance requirements of the BCA. An example of a deemed-to-satisfy provision is: 'ceiling heights must be not less than 2.4 metres in a habitable room'.

At Level 4b are the 'alternative solutions'. The key to the performance-based BCA is that there is no obligation to adopt any particular material, component, design factor or construction method. An approval authority may still issue an approval if it differs in whole or in part from the deemed-to-satisfy provision described in the BCA if it can be demonstrated that the design complies with the relevant performance requirement.

back to top | next page