Chapter 8 Assessment methods
Part A5 of the NCC explains the evidence that is needed to show that the NCC requirements have been met and that the solution is ‘fit for purpose’. There are four means by which an approval authority can assess whether a compliance solution complies with the BCA:
- evidence of suitability;
- expert judgment; and
An approval authority may use any combination of them to assess compliance. These are referred to as ‘assessment methods’.
If a performance solution is chosen, any of the above assessment methods may be used to assess compliance, but the building proponent must ensure that the assessment method(s) chosen satisfactorily indicates that the performance solution will meet the performance requirements in the BCA. The nature of the assessment methods will vary depending on the complexity of the performance solution.
If a deemed-to-satisfy solution is chosen, only the evidence of suitability and expert judgment methods may be used.
Key features of each of the assessment methods are:
Evidence of suitability
While each volume has slightly different requirements, evidence of suitability (which may be subject to conditions) can generally be submitted in support of a proposal that a material, product, form of construction or design meets a performance requirement or deemed-to-satisfy provision and can consist of one, or a combination, of the following:
- a current CodeMark Australia or CodeMark Certificate of Conformity;
- a current Certificate of Accreditation;
- a current certificate issued by a product certification body that has been accredited by the Joint Accreditation System of Australia and New Zealand (JAS-ANZ);
- a report from an Accredited Testing Laboratory;
- a certificate from a professional engineer or other appropriately qualified person; and
- any other form of documentary evidence that adequately demonstrates suitability.
Verification methods prescribe alternative ways in which a solution complies with performance requirements and can include the following:
- Calculations: using analytical methods or mathematical models (including computer modelling or hand calculations);
- Tests: using a technical operation either on site or in a laboratory to directly measure one or more performance criteria of a given solution; and/or;
- Inspections: to confirm that a product or system is constructed and installed to ensure a level of performance is achieved.
Examples of NCC verification methods include:
- BV1 in NCC Volume One for structural reliability;
- DV1 in NCC Volume One for wire barriers; and
- 2.1 in NCC Volume Two for weatherproofing.
In keeping with the flexibility provided in the performance-based BCA, designers are not restricted to using a listed verification method. Other methods may be used if the relevant approval authority is satisfied that it establishes compliance with the BCA. However, in making a decision, an approval authority may have regard to the relevant deemed-to-satisfy provisions or verification methods provided for in the BCA.
Where physical criteria are unable to be tested or modelled by calculation, the opinion of a technical expert may be accepted. This is referred to as the use of expert judgment. This judgment is based on the experience of an expert using reference material and documents to support a conclusion and is usually applied where the performance requirements are difficult to quantify.
This method involves comparing deemed-to-satisfy provisions and the proposed performance solution. If it can be demonstrated to an approval authority that the performance solution complies in an equivalent or superior way to a deemed-to-satisfy provision, then it will be deemed to meet the relevant performance requirement. In carrying out this comparison, the applicable deemed-to-satisfy provision and performance solution both need to be subject to the same level on analysis using the same methodology.
Under this hierarchy an applicant can use any materials, components, design factors or construction methods which comply with the relevant performance requirement. For Australia, this is a significant move away from sole reliance on prescriptive requirements and is designed to encourage innovation and the use of new technology.
However, the BCA still caters for those who prefer specific guidance, or wish to continue to use traditional building methods. The deemed-to-satisfy provisions of the BCA continue to provide detailed prescriptive methods for establishing compliance with the performance requirements.