A certificate of design compliance, often shortened to CDC, is a certificate signed by a registered building surveyor stating that the design of a proposed building complies with the applicable building standards for council approval. It is issued on form BA3. Without one you cannot lodge a certified building permit application, and your council will not issue a permit until either you obtain one or its own surveyors produce it.
It certifies the design, before anything is built. Not the finished work.
Who Can Issue a CDC
Only a registered building surveyor.
Not your draftsman. Not your builder. Not your engineer, though the engineer’s certification usually forms part of what the surveyor relies on.
You have two options:
Engage a private registered building surveyor. They assess your plans, issue the CDC, and you lodge it with a certified application. Faster, and the council’s prescribed fee is lower.
Let the council do it. On an uncertified application the council’s surveyors assess the plans and issue the certificate themselves as part of processing. Slower, and the council’s prescribed fee is higher.
Either way the certificate gets issued. The question is who issues it and when you find out the answer.
What the Surveyor Assesses
The full design, against the National Construction Code and the applicable standards.
For residential work that means working through your drawings on:
- structure and footings, usually relying on an engineer’s certification
- fire separation from boundaries and other buildings
- damp and weatherproofing, including the membrane under the slab
- room heights, light and ventilation
- wet areas and waterproofing
- glazing, safety glazing and fall protection
- smoke alarms
- energy performance, cross-checked against the rating report
- termite management
- bushfire construction, where the lot is bushfire prone
The certificate then references specific documents. Those referenced plans and specifications are what has been certified.
The Trap: Changing Drawings After the CDC
The most common and most expensive mistake on a certified application.
A CDC covers the documents it names. Revise a drawing afterwards and the certificate no longer describes what you are building.
We see it most often with windows. The energy report and the CDC are both issued, then somebody changes a window size or type during pricing, and nobody tells the surveyor or the energy assessor. It surfaces at inspection, and by then it is expensive.
Lock the design before certification. If something has to change after, go back to the surveyor.
What a Certificate of Design Compliance Costs
The CDC itself is a professional fee, not a prescribed government charge. It varies with the complexity of the design.
For residential work, budget roughly $400 to $650 for a straightforward certificate. More where the design carries variations, a performance solution, unusual construction, or a bushfire rating.
That is separate from your council’s prescribed application fee, which is:
| Route | Prescribed council fee |
| Certified, Class 1 or Class 10 | 0.19% of the value of the work, min $121 |
| Uncertified | 0.32% of the value of the work, min $121 |
So going certified means paying the surveyor and a lower council fee. Going uncertified means no surveyor fee and a higher council fee. On small jobs uncertified usually nets out cheaper. On larger ones the percentage gap can exceed the surveyor’s fee.
What If the Surveyor Will Not Certify?
They tell you what does not comply, and you fix it or change route.
This is the underrated value of the certified path. A surveyor declining to certify is a private conversation and a revision. A council refusing an application is a refusal on your property’s record.
Three common reasons a CDC gets held up:
A documentation gap rather than a compliance failure. No termite note, no glazing schedule, no smoke alarm locations, no waterproofing note. Nothing is wrong with the building, the drawings just do not say enough.
The energy report does not match the drawings. Orientation, window sizes and types, ceiling heights, roof colour and shading all have to be consistent between the rating certificate and the drawn set.
A departure from a deemed-to-satisfy provision. Where the design does not meet a prescribed solution, a performance solution may be available. It is prepared by a suitably qualified person, has to identify the relevant performance requirement, and has to be accepted by the surveyor issuing the certificate.
A performance solution is not a workaround. It is a different and more rigorous standard of proof, and it is the surveyor’s call whether to accept it.
Certificate of Design Compliance, Construction Compliance, or Building Compliance?
Three certificates, similar names, completely different jobs. People conflate them constantly.
| Certificate | Form | What it certifies | When |
| Design compliance | BA3 | The proposed design complies | Before you build |
| Construction compliance | BA17 | The completed work complies with the permit and is suitable for use | After you build. Needed for an occupancy permit |
| Building compliance | BA18 | An existing building complies with the applicable standards | For unauthorised work, a change of classification, or built strata |
If someone has told you that you need a certificate for a building that already exists, you are looking for a BA18, not a CDC. See retrospective building approval.
When You Need a Certificate of Compliance
- lodging a certified building permit application, always
- on an uncertified application the council produces one, so you do not obtain it yourself
For a change of use or unauthorised work you are in BA18 territory instead.
Certificate of Design Compliance Questions
What is a CDC in building?
A certificate of design compliance, issued on form BA3 by a registered building surveyor, certifying that a proposed design complies with the applicable building standards.
Who can issue a certificate of design compliance?
Only a registered building surveyor, either a private one you engage or your council’s on an uncertified application.
How much does a certificate of design compliance cost?
It is a professional fee rather than a prescribed one. Budget roughly $400 to $650 for straightforward residential work, more where there are variations, a performance solution or a bushfire rating.
How long does a CDC take?
It depends on the surveyor and the completeness of your drawings. A well documented residential set is usually days rather than weeks. An incomplete one goes back and forth.
Do I need a CDC for a patio or a shed?
If you are going the certified route, yes. On an uncertified application the council’s surveyors issue it. Either way the design has to be certified before a permit issues.
What is the difference between a CDC and an occupancy permit?
A CDC certifies the design before construction. An occupancy permit is granted after construction for Class 2 to Class 9 buildings. Class 1 and Class 10 buildings do not need occupancy permits.
My surveyor will not sign. What now?
Find out whether it is a documentation gap or a genuine compliance failure. Documentation gaps are usually a quick fix. Compliance failures need a design change or a performance solution.
