In short
Short answer: the Special Building Overlay (SBO) is a Victorian planning overlay set out in clause 44.05 of the Victoria Planning Provisions and applied to land through each council's planning scheme. In the clause's own words, its first purpose is: “To identify land in urban areas liable to inundation by overland flows from the urban drainage system as determined by, or in consultation with, the floodplain management authority”. (Department of Transport and Planning (Victoria), verified 27 Sep 2026)
An overlay sits on top of the land's zone and adds controls for one issue, whatever the zone is; a lot can carry several.
What it typically means for a buyer (Delora editorial, not legal advice): Land where urban drainage may be overwhelmed in a major storm. Building works typically need flood-safety conditions.
Check whether the Special Building Overlay applies to an address with Address Check. For a decision on a specific property, the official record is a Planning Property Report from VicPlan, and the council's schedule sets the local detail.
What the clause says
Clause 44.05 of the Victoria Planning Provisions (Special Building Overlay) states its purposes as: to identify land in urban areas liable to inundation by overland flows from the urban drainage system as determined by, or in consultation with, the floodplain management authority; to ensure that development maintains the free passage and temporary storage of floodwaters, minimises flood damage, is compatible with the flood hazard and local drainage conditions and will not cause any significant rise in flood level or flow velocity; and to protect water quality and waterways as natural resources by managing urban stormwater, protecting water supply catchment areas, and managing saline discharges to minimise the risks to the environmental quality of water and groundwater. (Department of Transport and Planning (Victoria), verified 27 Sep 2026)
Ask your conveyancer: What flood level applies, and has the property flooded before?
Shown on planning scheme maps as SBO.
What can I build? Worked examples
General examples of how state-wide rules apply, not an assessment of any property. The council's schedule and other overlays on the lot can add requirements; Address Check shows which apply to one address.
Example: extending a house on land in the Special Building Overlay
An owner plans a rear extension. Melbourne Water states that the Special Building Overlay requires a planning permit for buildings and works; councils in the Port Phillip and Westernport region refer those applications to Melbourne Water, and its consent may be needed before the council issues a permit (Melbourne Water, verified 21 Oct 2026). The permit exemption for a small second dwelling (granny flat) applies only where there is no flooding control (Department of Transport and Planning (Victoria), verified 20 Aug 2026), so a granny flat here needs a permit too.
How much of Victoria this covers
From the 2899 sample suburbs Address Check's export has processed so far — a lower bound, not a statewide total, until the export runs statewide.
98,912 land parcels and 205,137 addresses in the sample so far.
Councils with the most coverage
- Greater Geelong (11965 lots)
- Merri-bek (9511 lots)
- Port Phillip (7719 lots)
- Glen Eira (7281 lots)
- Kingston (6717 lots)
- Frankston (5846 lots)
Suburbs with the highest share
- Balaclava — 86% of addresses checked (3456)
- Whittington — 72% of addresses checked (1536)
- St Kilda West — 55% of addresses checked (1157)
- Newcomb — 50% of addresses checked (1467)
How it has changed since 2017
Vicmap Planning's published scheme history tracks where the Special Building Overlay has applied since 2017-07-30, recording when it was added to or removed from a parcel and the gazettal date where one is recorded. Address Check shows this timeline for any specific address — check below.