Granny flat rules in Queensland, explained

Queensland granny flat rules come from three places at once: the state's planning law, your council's planning scheme, and the building codes. Most people only hear about one of them, usually the size cap, and find the other two when the certifier rings. This is the whole picture, in the order you'll meet it.

The short answerA granny flat is a secondary dwelling: a second home on the same lot, subordinate to the main house, that can't be sold separately. Your council decides whether it needs a planning approval. It always needs a building approval from a licensed certifier and a plumbing permit from council. It's built as a Class 1a home under the NCC, with Queensland's own energy, flood and bushfire rules on top. Size, setbacks and charges vary by council.

String lines and timber set out across a backyard before the footings go in, on the Milton renovation

What a secondary dwelling is

The Planning Regulation 2017 defines a secondary dwelling as a dwelling on a lot that's used in conjunction with, but subordinate to, another dwelling on the same lot. It can be attached to the house or freestanding. A dwelling house, in planning terms, is one dwelling, or two where one is a secondary dwelling. That's why a granny flat is usually treated as part of a house, not as a second development.

The state draws the line against a dual occupancy. A secondary dwelling always comes with a main house and is generally smaller in size and scale. A dual occupancy is two dwellings that can be the same size. If your plan is two equal homes, you're in dual occupancy territory, with different approvals and charges. And since September 2022, who lives in a secondary dwelling is not a planning question: you can rent it to anyone. Our renting guide covers that.

What we'd sayLot size, overlays and crane access decide more than the design does. Check those first, then pick the home.Get a quote

Planning approval vs building approval

Planning approval is about whether the use is allowed on your land, and it comes from council under its planning scheme. In most residential zones across South East Queensland, a granny flat that meets the scheme's rules on size, distance from the house, setbacks and parking is accepted development. That means no planning application at all. Miss a rule, or sit in an overlay like Brisbane's character overlay, and it becomes assessable, which means a development application and usually a town planner.

Building approval is about whether the building is safe and compliant. It's always needed, for every new granny flat and for any existing structure converted into one.

Setbacks are in the middle of a change. The new Queensland Housing Code sets state-wide siting rules for detached houses and secondary dwellings, covering height, setbacks, privacy, parking, site cover and open space. It started on 1 September 2026, but it only applies in a council area once that council amends its planning scheme to adopt it. Councils have until 1 September 2029. Until then, the old QDC siting parts or the council's own rules apply. Check our council pages for where your council is up to.

Who the certifier is

The building certifier is the person who issues your building approval. They're licensed by the QBCC and can be private or work for council. You, or your builder, engage them. They check the plans against the NCC and the Queensland Development Code, collect the engineering and the BAL, flood and wind information, issue the approval, inspect the work at set stages, and sign off at the end.

The certifier isn't council's planning officer and doesn't decide planning questions. If your granny flat needs a development approval, that has to be in place first. Pick a certifier who works in your council area. They'll know its overlays and its quirks.

New wall frames standing on the deck of the Milton renovation, ready for the roof

The building codes: Class 1a and energy rating

Under the NCC, a freestanding granny flat is a Class 1a building, the same class as a house. If it's attached to the main house, the two are separate Class 1a dwellings and the code's fire separation rules apply to the wall between them. Queensland is still on NCC 2022. NCC 2025 starts here on 1 May 2027, a year later than the national release.

Energy is where Queensland has its own rules, in QDC MP 4.1, Sustainable buildings. The version in force from 14 August 2026 gives a home three pathways:

Home	What it must achieve
Standard Class 1a home	The NCC energy requirements, which for thermal performance means 7 stars NatHERS
Small home: detached, 50 m² floor area or less	5 stars, or 4.5 stars with a 0.5 star credit, or 4 stars with a 1 star credit
Raised floor: at least half the floor over an unenclosed space	6 stars, or 5.5 stars with a 0.5 star credit, or 5 stars with a 1 star credit

The small home and raised floor pathways still have to meet the total thermal energy load limit. They drop only the separate heating and cooling caps. For a granny flat these are a big deal. A one bedroom flat under 50 m² on stumps or piers fits both, and the lower star target is easier to hit without double glazing everywhere. Your energy assessor runs the rating, and the certifier checks it.

Bushfire: the BAL

If council has designated your block as bushfire prone, the building code's bushfire rules apply. The site gets a Bushfire Attack Level, from BAL-LOW to BAL-FZ, set by the vegetation around you, the slope and the distance between them. The BAL, not your taste, decides the windows, screens, cladding, decks and subfloor. Plenty of acreage and bush-edge blocks in SEQ carry one. Our bushfire guide goes level by level.

Flood levels

Councils designate flood hazard areas under the Building Regulation 2021 and declare the defined flood level for them. QDC MP 3.5 then sets the floor height. The flood hazard level is the defined flood level plus a freeboard, which is 300 mm unless council declares more, and habitable floors go at or above it. On a low block that can mean a raised floor, taller piers, flood-resistant materials below the line and services kept up high. Check your council's flood map before you pick a design. A raised home on piers often handles a flood level better than a slab.

Whatever the rules say, leave room for the Hills Hoist.

Wind classification

Every home is designed for a wind class from AS 4055, Wind loads for housing. The class comes from the wind region, the terrain, the shielding from nearby buildings and the topography. N classes are non-cyclonic, C classes are cyclonic. Your engineer or certifier sets it, and it drives the tie-downs, the bracing and the window ratings.

The 2021 edition of AS 4055 split Region B into B1 and B2. Under NCC 2025, B1 stays non-cyclonic and B2 is treated as cyclonic, so a B2 site moves onto C classes and cyclonic detailing such as cyclic-tested metal roofing and AS/NZS 4505 garage doors. On the NCC map, South East Queensland's coast is B1. B2 is a band further north, inland of the cyclonic Region C. If you're building from about Bundaberg north, ask your engineer which side of the line you're on before you lock in a roof.

Plumbing approval and infrastructure charges

Plumbing for a new building is permit work under Queensland's plumbing law. Your plumber or builder applies to council on Form 1 before work starts, council inspects at set stages and issues a compliance permit at the end. Council has 10 business days to decide a standard application. Using the plumbing before the final inspection is an offence.

Infrastructure charges are set by each council in a charges resolution under the Planning Act 2016, and they swing a lot. Gold Coast's resolution exempts a secondary dwelling up to 80 m². Logan charges a secondary dwelling as a dwelling. Redland only charges granny flats over its size caps. Others don't name secondary dwellings at all. Ask council in writing before you budget. Our council pages carry what we found for each one.

Want to know what applies on your block? Send us the address. We'll check the zone, the overlays, the flood and bushfire maps and the access, and tell you straight.

Sources, checked October 2026

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