Granny Flat Site Planner — can a 30 m² or 60 m² second dwelling fit on this block?
Search any Victorian or Queensland address, or click a lot on the map above. The planner measures your actual parcel against the state rules that decide buildability — boundary setbacks, easement clearances and the width of the side access corridor a builder needs to get materials into the backyard — then places a 30 m² and a 60 m² unit on the largest compliant footprint it can find. It is free, needs no login, and it will tell you no when the answer is no.
What question this tool settles
Most people asking "can I build a granny flat" are really asking three separate questions at once: is it allowed here, does it physically fit, and can a builder actually get to the spot where it fits. The first is a planning question, the second is geometry, and the third is the one that quietly kills projects after money has been spent on drawings. This planner answers the second and third directly from mapped data, and screens the first against the current state rules.
The access corridor is the part no other free tool measures. The planner traces the clear gap between your existing house (or garage, carport or shed) and each side fence, and reports both its narrowest pinch point and its widest point — because a corridor that is 4 metres wide for most of its length and 0.8 metres at one point is a 0.8-metre corridor. Below about 1 metre nothing gets through. Between 1 and 3 metres, materials are hand-carried, which adds labour cost to every stage of the build. At 3 metres or more, machinery and prefabricated modules can reach the backyard, which is the difference between an 8-week build and a 12-week one.
A unit that only fits by sitting on an easement is never scored as a pass. It renders red-dashed and downgrades the verdict, because building over a sewer or drainage easement requires build-over consent from the water authority and is routinely refused for habitable rooms. That single rule is the most common reason a backyard that "looks big enough" is not.
The rules it applies
Victoria. Amendment VC253, gazetted 14 December 2023, introduced the Small Second Dwelling provisions. A second dwelling of 60 m² or less needs no planning permit where the lot sits in the General, Neighbourhood or Residential Growth Zone, is larger than 300 m², carries no more than one existing dwelling, and is not caught by an overlay or a restrictive covenant. A building permit is always required regardless. Boundary setbacks come from the Building Regulations 2018 siting provisions — reg 79 requires at least 1 metre from side and rear boundaries for walls up to 3.6 m high — and are assessed per lot rather than as a single flat number.
Queensland. Secondary dwellings run under the Planning Regulation 2017 as amended by the 2022 rental reform, which from 26 September 2022 allows a secondary dwelling to be rented to someone outside the household anywhere in the state. Siting comes from the Queensland Development Code MP 1.2: a single-storey dwelling with walls up to 4.5 m mean height is generally set back at least 1.5 metres from side and rear boundaries, half a metre more than Victoria. Maximum floor area is set by the local council planning scheme rather than the state — roughly 80 m² in Brisbane and 70 m² in several south-east Queensland councils — and the planner checks the cap for the lot’s own local government area.
One correction worth making plainly, because the internet repeats the error and we have repeated it ourselves: there is no 550–600 m² minimum lot size for a granny flat in Victoria. The only lot-size number in the planning scheme is 300 m². The 550–600 m² figure is PremiumRea’s own commercial filter for whether a block is worth buying for this strategy. Plenty of smaller lots are perfectly legal to build on, and a 400 m² block in the General Residential Zone does not need a planning permit on lot-size grounds.
Where the data comes from
Victorian parcels, easements, planning overlays and address points come from Vicmap, the state’s authoritative digital cadastre, served here from per-suburb caches so the map stays fast. Building footprints are read from Overture Maps first, falling back to the Vicmap building layer and then to OpenStreetMap, because no single footprint source has complete coverage — new estates and recent extensions are frequently missing from all three, which is why the tool lets you trace the house yourself when what it drew is wrong.
Queensland runs live against QSpatial, the state ArcGIS service, for cadastre (including road parcels), easements, the address database and LiDAR-derived building outlines. Council overlay hits are precomputed per lot rather than queried live, because the council ArcGIS servers are not reachable from a browser.
Satellite imagery is aligned per-lot before any geometry is drawn on it. Google serves differently-registered orthophoto batches at different zoom levels, and the offset between them can reach about two metres — enough to make a compliant setback look like a breach, or the reverse. Every overlay you see is drawn on tiles fetched at the same zoom level the measurement ran on.
What it cannot see
This is a geometric and regulatory screen, not a feasibility report, and the gap between the two is where money is lost. The planner cannot see a title covenant or a Section 173 agreement restricting a second dwelling, an unregistered easement, a sewer main whose real position differs from the mapped alignment, the bearing capacity of the ground, a tree protected under a local law, an existing structure built without a permit, or what your relevant building surveyor will require on the day. A green verdict means the block is worth investigating properly. It does not mean you can build, and nothing on this page is planning or building advice.
Frequently asked questions
How close to the fence can I build a granny flat in Victoria?
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Under Building Regulations 2018 reg 79, a small second dwelling with walls up to 3.6m high must be set back at least 1 metre from side and rear boundaries. The PremiumRea planner applies this 1m clearance to every fence line and also keeps 1m clear of any sewer or drainage easement, which water authorities require for access.
Can I build a granny flat over an easement?
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Generally no — building over a sewer or drainage easement requires build-over consent from the water authority and council, and is often refused for habitable structures. The PremiumRea planner places units clear of easements automatically; if a unit only fits on top of an easement, the tool flags it explicitly instead of approving the site.
Does my driveway matter for building a granny flat?
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Legally no, practically yes. The planner measures the side access corridor between your house and the fence from cadastre and footprint data, reporting both its narrowest and widest points. Under about 1 metre nothing can get through; 1–3 metres means hand-carried materials; 3 metres or more lets machinery and prefabricated modules reach the backyard.
How close to the boundary can I build a granny flat in Queensland?
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Under the Queensland Development Code (MP 1.2), a single-storey secondary dwelling with walls up to 4.5m mean height must generally be set back at least 1.5 metres from side and rear boundaries — half a metre more than Victoria. The PremiumRea planner applies the 1.5m clearance to every QLD fence line plus 1m clear of sewer and drainage easements (QDC MP 1.4 build-over rules).
Can I rent out a granny flat in Queensland?
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Yes. Since 26 September 2022, Queensland planning rules allow secondary dwellings to be rented to people outside the household, statewide. Maximum size still depends on the council planning scheme — for example around 80m² in Brisbane and 70m² in several SEQ councils — which the planner checks against the lot’s local government area.
Do I need a planning permit for a granny flat in Victoria?
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Usually not. Amendment VC253, gazetted 14 December 2023, created the Small Second Dwelling provisions: a second dwelling of 60m² or less needs no planning permit where the lot is in the General, Neighbourhood or Residential Growth zone, is larger than 300m², already has no more than one dwelling, and is not caught by an overlay or restrictive covenant. A building permit is always required regardless. The 300m² figure is the only lot-size number in the scheme — below it a permit is required, not prohibited.
Is there a minimum block size for a granny flat in Victoria?
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The only lot-size figure in the planning scheme is 300m². The 550–600m² minimum widely quoted online — including previously by PremiumRea — is a commercial rule of thumb about which blocks are worth buying for this strategy, not a legal requirement. Plenty of sub-550m² lots are perfectly legal to build on, and a 400m² block in the General Residential Zone does not need a planning permit on lot size grounds.
What does this planner not tell me?
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It is a geometric and regulatory screen, not a feasibility report. It cannot see a title covenant, a Section 173 agreement, an unregistered easement, a sewer main whose real position differs from the mapped one, the ground’s bearing capacity, tree protection under a local law, or what your building surveyor will require on the day. A green verdict means the lot is worth investigating; it does not mean you can build.