Before you quote a granny flat, confirm which approval path the site can use: council approval through a development application, or a complying development certificate from council or an accredited certifier. In New South Wales, a granny flat can be certified as complying development without a development application if it meets the standards in the Housing SEPP. If the site does not meet them, the job takes a different path, and the price and timeline change with it.
The rules below are New South Wales only, taken from the state planning pages. Other states have their own rules, and councils add conditions. This is a checklist for builders and is not approval advice. Check the current rules with the council or a certifier before you price.
Council approval or complying development: which path applies
The NSW Government says a granny flat can be certified as complying development, by a council or an accredited certifier, without a development application, if it meets the standards in State Environmental Planning Policy (Housing) 2021 (NSW Government, granny flats). It must be built alongside another dwelling, called the principal dwelling, on the same lot. It cannot be on a separate strata or community title lot.
The state’s page on secondary dwellings adds a few points that matter before you quote (NSW Government, secondary dwellings):
- They are permitted in residential zones R1 to R5. Other zones may allow them if the council’s local controls permit.
- For complying development, the minimum lot size is 450 square metres, unless the secondary dwelling sits entirely within an existing dwelling house. Below that, a development application to council may still be possible.
- The floor area calculation includes the principal dwelling, the secondary dwelling and any attached carport, garage, balcony, deck, patio, pergola, terrace or verandah. The limits are in Schedule 1 of the Housing SEPP, which the page links to but does not reproduce.
- Only one principal dwelling and one secondary dwelling are allowed per site, and a lot with a secondary dwelling cannot be subdivided.
The first question to ask the homeowner is the address and the lot size. Many enquiries stop there. How a complying development certificate works more generally, including the documents and timing, is in complying development certificate for builders. This is general information, not planning or legal advice: check the rules for the lot with the council, an accredited certifier or a solicitor.
Site checks that change the price
Even when the path is clear, the site decides the cost. On the first visit, look at:
- The fall of the land, and whether a retaining wall or extra footings are needed.
- Soil type and any signs of fill, rock or reactive clay.
- Existing structures to demolish or work around: sheds, pools, large trees.
- Setbacks to boundaries, and the distance to the principal dwelling.
- Whether the site is in a mapped overlay such as bushfire, flood or heritage. The state pages we opened do not give figures for these, so ask the council or certifier what applies to the lot.
Photograph the lot from each boundary, and the proposed footprint. See how to quote a job for the full site visit sequence.
Services, access and easements
Services can add a lot to a granny flat, and the homeowner often does not know where they run. Find out:
- Where the sewer, stormwater, water, power and gas connections are, and how far the new dwelling is from each.
- Whether the existing connections can carry the extra load, or whether upgrades are needed.
- Whether there are easements or services running through the footprint.
- How trucks, machines and materials get to the rear of the lot. Narrow side access can add labour, hand carrying and smaller deliveries.
The planning page says the Housing SEPP requires no additional parking, but to check existing consent conditions and speak to council if removing on-site parking. Raise it with the homeowner if the site is tight.
What the client must supply
Before you price, ask the homeowner for what exists already:
- The certificate of title, and a current survey if they have one.
- Drawings of the principal dwelling.
- Any previous approvals or consent conditions on the lot.
- Details of any covenants, body corporate rules or lender conditions that might apply.
- Who the owner is, and who signs. If more than one name is on the title, make sure all of them are on board before you start work.
If they have none of it, say so in the quote, and treat the early work as its own stage.
What to price first and what to qualify
Price what you can be sure of, and qualify the rest in writing. A sensible order:
- Early work first. Survey, design, approval documents and site investigation, as a separate stage. This is where a preliminary agreement fits. Check how your state treats early-stage fees and deposits before you write it.
- Build price second, with site-dependent items stated as assumptions or provisional allowances: excavation, retaining, service connections, and any extra the approval conditions add.
- Approval fees and certifier costs stated as in or out, and who pays.
Qualify on the phone first: is the lot big enough, who owns it, is there a main dwelling already, and what is their budget and timing? How to qualify building enquiries has the list. A granny flat enquiry from a homeowner who has not checked their lot is the kind that produces a free quote and no job.
Once the price is out, the quotes page covers how we help builders follow it up.
Where to check current rules
Approval rules change. Use the source, not a summary, including this one:
- The NSW Government’s pages linked above, and Schedule 1 of the Housing SEPP for the floor area limits.
- The council’s local controls for the area, including its local environmental instrument.
- The council, or an accredited certifier, for the particular lot.
- For other states, that state’s planning department and the local council.
Write the date you checked into your quote file. If the rules move before the job is signed, you can show what you priced against.
Common questions
Do you need council approval for a granny flat in NSW?
Not always. A granny flat that meets the Housing SEPP standards can be certified as complying development by a council or an accredited certifier, without a development application. If it does not meet them, a development application to council may be needed.
What lot size do you need for a granny flat in NSW?
For complying development, the state page gives a minimum of 450 square metres, with an exception for a secondary dwelling entirely within an existing dwelling house. Below that, a development application may still be possible.
Can a granny flat be subdivided off?
The state page says a lot on which a secondary dwelling is built cannot be subdivided.
Do the same rules apply in other states?
No. Everything here is New South Wales. Check your own state and council.