Brisbane Flood Overlays: What They Mean for Your Design
Which Brisbane City Council flood tools to use for development and building certification — City Plan Online, the FloodWise Property Report and the Flood Awareness Map — and when overland flow requires a hydraulic assessment.
This guide is general information current at the time of writing. Planning rules and requirements change and every property is different — we confirm what applies to your specific site as part of our service.
Flood information: use the right tool for the question
Brisbane City Council provides several flood information tools, but they serve different purposes. For development assessment and building certification, the key starting point is Brisbane City Plan Online and its interactive mapping. The FloodWise Property Report provides supporting technical flood information, while the Flood Awareness Map provides supplementary information to help understand broader flood risk.
Brisbane City Plan Online — the assessment mapping for development and certification
Brisbane City Plan Online is the primary tool for identifying the planning scheme mapping and requirements that apply to a property. For development applications and building certification, the interactive mapping should be used to check whether the site is affected by the Flood overlay, including Brisbane River, creek/waterway and overland flow flood planning areas.
The Flood overlay mapping determines which City Plan flood provisions may apply to the proposed work. It should be considered together with the Flood overlay code, the relevant tables of assessment, the proposed development and any other applicable overlays or site-specific requirements.
The Flood Awareness Map should not be used in place of City Plan Online when determining development or certification requirements.
Official reference: Brisbane City Council — City Plan Online — Interactive Mapping / Flood Overlay.
Overland flow — hydraulic assessment is required
Where City Plan Online identifies a property as affected by an overland flow flood planning area, particular care is required.
Council does not generally provide an accurate minimum habitable floor level for an overland flow path through the FloodWise Property Report. An appropriately qualified Registered Professional Engineer of Queensland (RPEQ) with flood or hydraulic expertise is required to undertake the necessary hydraulic assessment and derive the applicable flood level and minimum habitable floor level for the proposed development.
The hydraulic assessment may also need to demonstrate that the development maintains the conveyance of overland flow and does not adversely increase or redirect flooding onto neighbouring properties.
Overland flow can also trigger development assessment under City Plan. The requirement for development approval must be determined from the City Plan Online mapping and the applicable tables of assessment for the particular proposal, rather than from the Flood Awareness Map or the absence of a floor level in a FloodWise Property Report.
A missing minimum habitable floor level is therefore not an indication that no flood requirements apply.
FloodWise Property Report — supporting technical flood information
The FloodWise Property Report provides property-specific technical flood information based on the adopted flood planning information in City Plan. Depending on the property, it can include flood levels, flood planning areas, development flags, ground-level information and minimum habitable floor level requirements.
It is a useful technical resource for designers, engineers, surveyors, builders and certifiers, but it should be used in conjunction with City Plan Online rather than as a substitute for checking the applicable City Plan mapping and assessment requirements.
For properties affected by overland flow, the report may identify an overland flow development flag but may not provide a minimum habitable floor level. In these circumstances, a hydraulic assessment by an appropriately qualified RPEQ is required to establish the applicable flood and habitable floor levels.
A FloodWise Property Report may also omit a minimum habitable floor level for other circumstances, such as a large allotment. Further professional assessment may therefore be required.
Official reference: Brisbane City Council — FloodWise Property Report.
Brisbane Flood Awareness Map — supplementary flood-risk information
The Flood Awareness Map is a supplementary tool intended to help property owners and residents understand their general flood risk. It provides information about the likelihood and extent of different types of flooding, including river, creek, overland flow and storm tide flooding, as well as historical, rare and very rare flood events.
It can be useful for understanding a property’s broader flood exposure and considering flood preparedness and resilience.
However, the Flood Awareness Map is not the mapping used to determine City Plan development assessment or building certification requirements. For those purposes, the relevant City Plan mapping and planning provisions should be checked through City Plan Online.
Official reference: Brisbane City Council — Flood Awareness Map.
Designing with flood requirements
Flood information often shapes the design itself, not just the paperwork. On some flood-affected properties, raising and building under can lift existing living areas to manage flood impacts, subject to the property’s flood levels and the applicable planning and building requirements. For a new home, floor levels and the use of lower-level spaces can be planned around the flood requirements from the outset. Our guide Renovate or Knockdown Rebuild in Brisbane? compares the options in more detail.
Unsure how a flood overlay affects your property? Get in touch and we’ll review the flood information as part of your design.