Few projects reach completion exactly as first drawn. A client changes a window, the builder swaps a product, or the engineer redesigns a footing. If you hold a complying development certificate (CDC), those changes may need a formal modification before they are built. Here is how it works.
Can a CDC be changed?
Yes. Section 4.30 of the Environmental Planning and Assessment Act 1979 allows a CDC to be modified. The application is made by the original applicant or another person entitled to act on the certificate.
The key limit is that the development, as modified, must still be complying development. Every numeric standard in the code that applies, such as landscaped area, setbacks, site coverage and height, still has to be met. A modification cannot be used to approve something the code does not allow.
Changes that usually fit, and ones that do not
Changes that often stay within the code include:
- moving or resizing windows where privacy standards are still met;
- internal layout changes that do not affect the external envelope;
- swapping external materials or finishes;
- small changes to the footprint that keep within setback, height and coverage limits.
Changes that often fail include extra floor area beyond the code's limits, extra height, reduced setbacks or a new element the code does not permit. When a change breaks a standard, it can't be approved by modifying the CDC. In that case you would normally need a development application to council. Our guide on CDC or DA: picking the approval your home project needs explains the difference.
A proposed CDC variation pathway went on public exhibition between May and June 2026. It would let councils approve minor departures from some standards. As of October 2026 it is a proposal only and not in force, so do not plan around it.
Changes people forget about
- BASIX. Changing windows, insulation, hot water or tank size can affect BASIX commitments. The certificate may need updating to match.
- Engineering. Revised structural or stormwater design can change what is built, so it should be reviewed before work goes ahead.
- Levels. Raising a floor level or changing cut and fill can push the building over a height limit.
- Builder substitutions. Product swaps that seem minor can affect fire, waterproofing or energy compliance.
How to apply
- Speak with your certifier ahead of building anything that differs from the approved plans.
- Have your designer prepare amended drawings with every change clearly marked against the approved set.
- Update supporting documents such as BASIX, engineering and any affected reports.
- Lodge the modification through the NSW Planning Portal with a short explanation of what changed and why.
- Ask your certifier whether the change affects any neighbour notice already given.
Do not build first and modify later. Work that departs from the stamped plans can delay your final inspection and your occupation certificate.
Keeping changes to a minimum
The cheapest modification is the one you never need. A careful check of the design before lodging, with input from the builder and engineer, catches many changes early. Our plan assessment service reviews drawings against the code before you lodge.
Once building starts, keep a simple change log. Note each request from the client or builder, whether it affects the approved plans, and what your certifier said. That record makes the final inspection far easier.
CertifiBuild issues and modifies complying development certificates for Class 1 and Class 10 work. If your approved design needs to change, request a quote and send us the approved plans with your proposed changes.
Local help across NSW
CertifiBuild certifies Class 1 and Class 10 work in 39 council areas. Local rules on these council pages are a good place to start: Waverley Council, Ku-ring-gai Council, Willoughby City Council, Hunter’s Hill Council, Penrith City Council, City of Newcastle.
Suburb pages with local planning notes: Castle Cove, Hunters Hill, Middle Cove, Penrith, St Ives, St Marys, Stockton, Tamarama, The Entrance, The Junction. You can also browse every service area.
Sources
- Complying development, NSW Planning Portal
- Summary of proposed variations and changes to complying development (PDF), NSW Planning Portal
- Complying development, NSW Department of Planning