Deemed-to-Satisfy or Performance Solution: how the NCC decides
The National Construction Code sets Performance Requirements, which are the outcomes a building has to achieve, and offers two ways to show you achieve them. The Deemed-to-Satisfy provisions are the pre-approved recipes: build it this way and compliance is assumed. A Performance Solution is the other route, used when the design does not follow the recipe. It is not a lesser form of compliance. Clause A2G2 lists the ways a Performance Solution is demonstrated: evidence of suitability (a CodeMark certificate or test report that covers the exact use), a verification method (the NCC's own test or calculation, such as the F3V1a weatherproofing risk score), expert judgement (a qualified engineer's assessment), or a comparison showing the design performs at least as well as the Deemed-to-Satisfy provisions.
The situations that trigger one
- Cladding that is not a Deemed-to-Satisfy system. Rendered fibre cement, mineral wool ETICS, AAC panel, rainscreens and most proprietary facades have to be shown to meet F3P1, either on a CodeMark certificate that covers the building's wind pressures and height, or by expert judgement with the F3V1a risk score. Brick veneer to AS 3700 and AS 4773 is Deemed-to-Satisfy under F3D5 and needs nothing. See the facade Performance Solution page.
- A window or glazing in a shower. The wet-area provisions want a waterproof wall to 1,800 mm above the floor; a window breaks it. The solution documents the sill, the sealed reveal and the upturn so the wall still keeps water out. See the waterproofing Performance Solution page.
- A balcony or terrace door threshold below the step-down. The membrane upturn height is set by the site wind class under AS 4654.2 and can be traded against designed stormwater retention. Our wind classification calculator gives the class and the minimum upturn.
- Omitting or substituting a membrane. A slab designed to be watertight without a sheet membrane, or a different system at a movement joint, is an expert-judgement solution with its own test and inspection regime.
- A basement. Australia has no below-ground membrane standard, so basement waterproofing is designed to BS 8102 and documented as a Performance Solution. Start with the BS 8102 basement calculator.
- An F3V1a score over 20. Above 20 the NCC calls for a specific weatherproofing design. Sometimes the better answer is a design change that brings the score under; we say so when it is on. See when the score is over 20.
What a Performance Solution report has to contain
The Performance Requirement answered limb by limb, not a general assurance. The assessment method named, with why it applies. Project-specific numbers: design wind pressures for the site with local pressure factors, the risk score with the factor breakdown that produces it, and the certificate limits the system has to sit inside. And the conditions: what has to be built, inspected and documented for the solution to hold. Certifiers read the conditions first. The things that get solutions sent back are answering a different question, wind pressures that differ between the wind report, the solution and the drawings, a score without its breakdown, and certificates that have expired.
New South Wales: the DBP Act changes the timing
For Class 2 buildings, and since 2023 Class 3 and 9c, the facade and waterproofing designs are regulated designs under the Design and Building Practitioners Act. The Performance Solution is part of the declared design, prepared and declared by a registered design practitioner before the work is done. It cannot be a document produced afterwards to explain what was built. A Performance Solution can still be written for an existing building, but in that case it documents an as-built condition and the certifier decides what it is worth.
Questions we get asked
What is an NCC Performance Solution?
A Performance Solution is the National Construction Code compliance pathway used when a design does not follow the Deemed-to-Satisfy provisions but still meets the Performance Requirement. Under NCC clause A2G2 it is demonstrated by one or more assessment methods: evidence of suitability, a verification method, expert judgement, or comparison with the Deemed-to-Satisfy provisions.
Is a Performance Solution a lesser form of compliance?
No. Deemed-to-Satisfy and Performance Solutions are both compliance pathways under the NCC. A Performance Solution carries conditions that have to be built and inspected, and that is where the real risk sits, not in the pathway itself.
Do I need a Performance Solution for brick veneer?
Usually not. Masonry to AS 3700 and AS 4773 is Deemed-to-Satisfy for weatherproofing under F3D5. A Performance Solution is only needed where the wall departs from those provisions.
What does a Performance Solution cost?
Excelo's Performance Solution report for a single system is typically $2,500 to $4,500 ex GST and issues in five to ten working days once the drawings and the wind data are in. Where a wind assessment or an F3V1a risk assessment is needed first, those are quoted separately.
Who prepares a Performance Solution in NSW?
For Class 2 buildings in NSW the facade and waterproofing designs are regulated designs under the Design and Building Practitioners Act, so the Performance Solution is prepared and declared by a registered design practitioner before the work is done. Excelo holds NSW Design Practitioner registration DEP0001529.