Not always. A granny flat, which NSW calls a secondary dwelling, can be approved as complying development: a complying development certificate (CDC) from the council or a registered certifier, with no development application. That works when it meets fixed standards. When it does not, it needs a development application (DA) to the council.
When a granny flat can be a CDC
- The lot is at least 450 square metres. On a smaller lot a granny flat cannot be complying development, attached to the house or not. The one exception is a granny flat built entirely within an existing house.
- It meets the standards in Schedule 1 of the Housing SEPP (State Environmental Planning Policy (Housing) 2021).
- The floor area fits. The limit counts the main house too, with any carport, garage, deck or verandah attached to either.
- The zone allows it. Secondary dwellings are permitted in the residential zones R1, R2, R3, R4 and R5. Other zones depend on the council’s local environmental plan.
A new house and a granny flat can be approved together, under one complying development certificate.
When it needs a DA
If the lot is under 450 square metres, or the design misses a standard, it may still be possible through a development application to the council, which judges it on its merits. That is the slower route.
In rural zones some councils’ plans also set a maximum floor area for a granny flat and a maximum distance from the main house (clause 5.5 of their local environmental plan).
Rules that apply either way
- One main house and one granny flat on the lot, no more.
- The lot cannot be subdivided to separate them.
- NSW’s housing policy asks for no extra car space for a granny flat. If building it removes existing parking, check the house’s own consent with the council first.
How long each route takes
A CDC takes a median of 4 days in NSW. A development application takes a median of 56 days. Complying development is faster because nobody is weighing the proposal: it meets the standards or it does not. A development application is assessed on its merits, can draw submissions from neighbours, and waits for the council’s view.
How long a development application takes varies by council: see DA times for every NSW council, or your council’s page.
The rules above are from NSW’s own page on secondary dwellings. Check the standards that apply to your lot with the council or a certifier before you rely on them.