BCA and Australian Standards (Nat)

The Building Code of Australia (BCA) is a uniform set of technical provisions for the design and construction of buildings and other structures throughout Australia . It is produced in two Volumes:

• Volume 1 for building classes 2 to 9; and
• Volume 2 for building classes 1 and 10, known as the “Housing Provisions”.

Australian Standards are published by Standards Australia on an “as needs basis” and generally take several years to be written and published. There are over 200 Australian Standards referenced in the BCA and over 1000 more standards indirectly referenced in the BCA.

The relationship between the BCA and Australian Standards affects the work of builders and contractors daily and it is important to be clear on when an Australian Standard is legally binding and when it is not.

This information sheet deals with Volume 2 only although the relationship between the BCA and Australian Standards is the same for both Volumes.

Objective of the BCA

The objective of the BCA is to achieve an acceptable degree of structural adequacy in buildings and to provide safe, healthy conditions and basic amenities for building occupants, through efficient and cost effective building requirements.

Performance Requirements

A minimum level of performance for each aspect of a building which provides structural support, safety and amenity, is set out in the BCA. These controls are known as “performance requirements” and they must be met to comply with the BCA.

Meeting the performance requirements can be achieved by a building solution that either complies with a deemed-to-satisfy provision or by formulating an alternative solution.

Deemed-to-satisfy provisions are set out in the BCA; therefore if you building using these provisions, no further evidence of compliance is required. However if you decide to build using an alternative solution, the proponent must provide evidence that the alternative solution complies with the performance requirements.

Parts of the building that do not contribute to the structural stability, safety, weatherproofing or healthy conditions, such as wall and floor tiling, internal wall lining, cabinetry or painting, are considered to be “decorative finishes” and are not covered by the BCA. Requirements for these items should be specified in the plans, specifications and scope-of-works that comprise the contract documents. Electrical and plumbing items (other than stormwater drainage) have separate laws and codes, therefore they are not included in the BCA.

Deemed-to-satisfy solutions

For most of the performance requirements, the BCA describes a “building solution” that is a “deemed-to-satisfy” solution.  These deemed-to-satisfy solutions are known as Acceptable Construction Practice (ACP), for example: 

Part 3.9.1 sets out an acceptable construction practice, which specifies dimensions and conditions for stairs and balustrades that will provide safe movement and access to and within a building.

Australian Standards

The BCA also recognises, for various reasons, selected Australian Standards and other documents that provide acceptable information on specific topics. Some examples are:  

• For the manufacture of materials that will give an acceptable performance, e.g. AS/NZS 4858 – Wet area membranes, AS/NZS 2904 –Damp-proof courses and flashings.
• For test methods that will confirm an acceptable performance of a material or form of construction, e.g. AS 1530 - Methods of fire tests on building materials components and structures, AS 1289 – Methods of testing soils for engineering purposes.
• For a building solution that is deemed-to-satisfy the performance requirements, e.g. AS 1684 – Residential timber framed construction (known as the Timber Framing Code), AS 3740 - Waterproofing of wet areas within residential buildings.

Note: Standards, or other documents, referenced to provide a “building solution” are referred to as an “Acceptable Construction Manual” (ACM)

In some cases, the BCA has an ACP and an ACM for the same performance requirement. For example, AS 3700 – Masonry structures and BCA, Volume 2 Part 3.3 Masonry. Where this occurs, the BCA is quite clear that both building solutions comply with the performance requirements even though each may contain different solutions.  Compliance with either solution is deemed to be compliance with the BCA. BCA 2007 has been amended with additional information to clarify this intention.

To be selected as a BCA reference document, any Standard, or other document, must meet strict guidelines established by the Australian Building Codes Board (ABCB) which:

• Require an assessment by a comprehensive cost/benefit analysis;
• That the document be written in regulatory terms;
• Must be judged by the ABCB to meet the objectives of the BCA.

Standards that are not referenced in the BCA have no authority over any work unless they are required to be followed by the contract documents or any applicable legislation. It is not uncommon for these non-referenced standards to be used to judge building methods or workmanship, however, they are generally over-ridden by contractual requirements or manufacturer’s installation instructions.

Amendments to the BCA

A new version of the BCA is produced each year and incorporates any updated information or references, and editorial amendments. Each new version has the year of its release in the title such as “BCA 2007” and is “in force” from the 1^st of May of that year.

Where do you get a copy of the BCA?

You can purchase the BCA from the ABCB web site www.abcb.gov.au or by calling 1300 857 522 or e-mail bca@abcb.gov.au. Access is also available over the internet through a subscription with the ABCB and electronically from a CD-ROM that also contains access to the referenced Standards (depending on the purchase price). The CD-ROM and any Australian Standard can be purchased over the internet from www.saiglobal.com/shop or phone 1300 654 646.

For further information HIA members can contact HIA's Building Services staff in your region on 1300 650 620 or hia_technical@hia.com.au .

Ref No. NAT BCA 07-02

The above is intended to provide general information in summary form. The contents do not constitute specific advice and should not be relied upon as such. Formal specific advice should be sought by members with respect to particular matters before taking action. ABN 99 004631752