Thinking about adding a granny flat to your property? You're in good company. Across NSW, secondary dwellings have become one of the most popular ways for homeowners to boost rental income, support ageing parents or adult kids, and add real value to their block. But before the concrete gets poured, there's one step that makes or breaks the whole project, getting planning approval.

Get it right and you could be moving in within months. Get it wrong and you're looking at delays, redesign or worse, an unapproved structure. Here's what the rules say.

What Is a Secondary Dwelling, Officially?

In NSW planning law, a granny flat is called a "secondary dwelling" a self-contained home with its own kitchen, bathroom and living space, built on the same lot as your main house. It can be a standalone backyard build, attached to the existing house, or even above a garage. The rules sit under the State Environmental Planning Policy (Housing) 2021, known as the Housing SEPP, which is administered through the NSW Planning Portal.

Secondary dwellings are permitted in residential zones R1 to R5, and sometimes in other zones depending on your council's local environmental plan. One important catch is that you can't subdivide the lot and you can only have one principal dwelling plus one secondary dwelling on the property.

Two Pathways: Complying Development or DA

There are two ways to get approved:

Complying Development Certificate (CDC)

This is the fast track. If your design meets the standards set out in the Housing SEPP and your block is at least 450m² then a private certifier can issue a CDC for both the secondary dwelling and the main house under one approval, often within a matter of weeks rather than months.

Development Application (DA)

If your site doesn't meet the CDC standards due to heritage overlays, flood risk, bushfire-prone land or a lot under 450m² then you'll need to lodge a DA with your local council. This involves a more detailed, merit-based assessment.

Requirements Worth Knowing

A few standout rules from the Housing SEPP:

• Floor area is generally capped at 60m², including any attached carport, garage, deck, patio or verandah, unless another planning instrument allows more.

• No additional off-street parking is required under the Housing SEPP itself, though existing consent conditions may still apply.

• Once built, you'll need an occupation certificate for the granny flat and if it's a new build alongside a future main house, a final occupation certificate is required within five years.

• Regardless of pathway, the build must comply with the Building Code of Australia and National Construction Code.

Where Homeowners Can Get Tripped Up

The rules sound simple on paper but lot size calculations, setback requirements, overlapping local council provisions and floor area definitions can catch people out. A design that looks compliant on a sketch can fall outside the Code once a certifier checks the fine print and that can mean delays, redesign costs and lost time.

We Handle the Approval, So You Don't Have To

This is exactly the kind of detail we deal with every day. Whether your project is a straightforward CDC or a more complex DA, we can coordinate the entire planning approval process, from checking your site against the Housing SEPP to liaising with council or your certifier so your granny flat moves from idea to approved build smoothly.

And it doesn't stop at granny flats. If you've got extensions, renovations or any other building works on the horizon, we'd love to help you navigate the approval process for those too.

Ready to find out if your block qualifies for fast-track approval?

Get in touch with our team today.

If your home has a deck, garage conversion, granny flat or extension that hasn't been approved by a certifier or your local council then you are not alone. Unapproved building work is far more common across NSW than most owners realise and it can cause issues if it is left unresolved.

What Counts as Unapproved Building Work

In NSW most building work needs either a development consent from council or a complying development certificate from a private certifier before it begins. Work carried out without this approval, work that varies significantly from the approved plans, or a change of use that was never authorised can all be classed as unapproved under the Environmental Planning and Assessment Act 1979.

Common examples include garage conversions used as living space, sheds or pergolas that exceed exempt development limits, internal alterations that change a building's layout, and granny flats added without consent.

Why It Matters

Unapproved work is not just a paperwork issue. Local councils can issue stop work orders or orders requiring a structure to be repaired, altered or demolished. Insurers can decline cover for unapproved structures which leaves owners financially exposed if something goes wrong. When it comes time to sell, many buyers and their conveyancers ask for proof that existing structures are approved. Unapproved work can delay a sale, reduce a property's value or even cause a deal to fall through.

How Unapproved Work Gets Regularised

Once a building has already been built it is not possible to apply for a retrospective development consent or construction certificate covering its construction. Instead owners generally need to apply for a Building Information Certificate from council. A BIC does not approve the use of the building but it confirms the structure is sound, and it prevents council from ordering its demolition or repair, for matters that existed before the certificate was issued, for the following seven years.

Where the structure is also being used in a way that needs consent, such as a converted garage being lived in as a granny flat, a development application is usually required as well so that council can assess and approve the ongoing use. A BIC is the path councils most commonly expect property owners to follow when regularising older or unapproved work.

The process usually calls for site plans, architectural drawings and sometimes a structural engineer's report confirming the building meets the Building Code of Australia. Every council applies its own procedures, so the exact documentation required can vary.

Getting It Sorted Properly

Dealing with unapproved building work on your own can be slow and stressful, especially if you are also trying to sell or refinance your property. We help NSW property owners work out exactly what approval is missing, coordinate the right documentation, and facilitate the application with council from start to finish, whether that means a Building Information Certificate, a development application or both.

If you have any other building work planned down the track, we can also handle that planning approval for you so your next project starts on the right footing from day one.

Get in touch with our team today to find out what your unapproved structure actually needs.