Answer first: On flood-affected NSW land, confirm flood notations on a Section 10.7 planning certificate, obtain council flood levels, then design habitable floors to the local flood planning level (FPL). Complying development on flood control lots needs hydraulic certification that the building envelope is outside floodways, flood storage, flow paths, high hazard and high risk areas — otherwise use a Development Application under clause 5.21.
Author: Franz Phan, Senior Planning Consultant, giantA Pty Ltd · Updated 10 September 2026
Why do flood planning levels matter before you sketch a floor plan?
Flood planning levels sit at the intersection of risk, structure and approval pathway. If you fix a ground-level living room before you know the FPL, you can end up raising the whole house late, rebuilding wet-area setouts, or abandoning a CDC pathway after documentation is half complete.
giantA treats flood due diligence as part of early site assessment — alongside survey, services and overlays — not as a late “planning condition” surprise.
Related giantA reading: Section 10.7 planning certificates, Exempt vs CDC vs DA NSW 2026, NCC DA & CDC compliance checklist.
What does a Section 10.7 certificate tell you about flooding?
Under the Environmental Planning and Assessment Regulation 2021, Schedule 2 requires councils to state on a planning certificate whether the land (or part of it) is within the flood planning area and subject to flood-related development controls, and whether the land (or part of it) is between the flood planning area and the probable maximum flood (PMF) and subject to flood-related development controls.
Those notations are awareness tools — they do not replace a Flood Information Certificate, flood study extract, or engineer advice for design levels. If either box is marked, assume flood controls may affect floor levels, materials, cut/fill and pathway choice until you prove otherwise.
What is a flood planning level (FPL) in NSW?
In plain practice, an FPL is the design water level used for planning and building controls on flood-prone land — commonly tied to a defined flood event plus a freeboard adopted through the council’s flood risk management (FRM) process.
The compulsory Standard Instrument LEP clause 5.21 Flood planning defines flood planning area by reference to the Flood Risk Management Manual (NSW Government, June 2023, ISBN 978-1-923076-17-4) and points readers to the Considering Flooding in Land Use Planning Guideline (14 July 2021).
Councils remain primarily responsible for managing flood risk in their LGAs through flood studies and floodplain risk management plans. That means your FPL is local. Do not copy a neighbour’s floor level from another LGA, and do not treat a generic “500 mm freeboard” as a statewide rule — many Sydney councils use figures in that order of magnitude for mainstream flooding, but overland flow precincts and special flood considerations can differ. Confirm the Section 10.7 flood notations, council flood mapping or Flood Information Certificate, DCP flood clauses, and advice from a suitably qualified hydraulic engineer where the site is constrained.
Sources: clause 5.21 Standard Instrument LEP; NSW Flood Risk Management Manual 2023; NSW Planning flooding policy pages.
What does clause 5.21 require on a Development Application?
Clause 5.21 is compulsory in Standard Instrument LEPs. Consent must not be granted for development the consent authority considers within the flood planning area unless it is satisfied the development is compatible with the flood function and behaviour on the land; will not adversely affect flood behaviour so as to detrimentally increase flood affectation of other development or properties; will not adversely affect safe occupation and efficient evacuation, or exceed evacuation route capacity; incorporates appropriate measures to manage risk to life in a flood; and will not adversely affect the environment (including avoidable erosion, siltation, riparian damage or bank instability).
When deciding, the consent authority must also consider climate-change impacts on flood behaviour, the intended design and scale of buildings, evacuation measures, and the potential to modify, relocate or remove buildings if the area is later impacted by flooding or coastal erosion. That is a merit test — which is why flood-affected homes often land on the DA pathway even when the architectural envelope looks “CDC-shaped”.
Can you still use a CDC on a flood control lot?
Sometimes — with tight constraints. Certain SEPPs (including the Codes SEPP for many residential complying development types, plus related Housing and Infrastructure SEPPs for other uses) treat flood control lots specially.
In broad terms, complying development on a flood control lot generally cannot proceed unless the council or a professional engineer specialising in hydraulic engineering certifies that the part of the lot proposed for development is not a flood storage area, floodway area, flow path, high hazard area, or high risk area. Additional SEPP standards can also require minimum finished floor levels and flood-compatible materials. If you cannot get that certification, or the design needs variation from numeric CDC standards, plan for a DA assessed under clause 5.21 and the local DCP.
Always read the current Codes SEPP clauses and your certifier’s pathway advice against the live legislation — SEPP wording is amended periodically.
Related: Exempt development vs CDC vs DA.
DA vs CDC on flood-affected residential lots
| Issue | Development Application (DA) | Complying Development (CDC) |
|---|---|---|
| Who decides | Council (merit under s 4.15 + cl 5.21) | Accredited certifier against SEPP standards |
| Flood planning area | Assessed against LEP cl 5.21 + DCP | Often blocked or constrained on flood control lots |
| Floor levels | Negotiated with council flood data / engineer | Must meet SEPP minima where CDC is available |
| Design flexibility | Higher — variations argued on merit | Binary — meet every standard |
| Extra reports | SEE, flood report / FIRA as required | Hydraulic certification + flood-compatible detailing |
| Typical when | Constrained flood function, evacuation issues, merit design | Clear certification that envelope avoids floodway/storage/high hazard/high risk |
How should designers set habitable floors and materials?
- Collect site flood facts early — 10.7 certificate, survey with levels to AHD, Flood Information Certificate, overland flow notes.
- Lock the FPL before locking room heights — habitable floors are commonly set at or above the FPL stated for the site; non-habitable spaces may have different rules in the DCP. Confirm with council documents, not hearsay.
- Detail below the FPL for wet exposure — flood-compatible materials, sacrificial linings where appropriate, resilient structure, and careful placement of switchboards, hot-water plant and HVAC.
- Test cut/fill and fencing — earthworks can change flood behaviour for neighbours; cl 5.21 expressly guards against detrimental off-site affectation.
- Plan evacuation and access — driveway grades, refuge spaces and route timing matter on higher-risk sites.
- Coordinate NCC wet areas and structure — raising floors changes stairs, damp-proofing, termite management and sometimes BASIX geometry. Pair this article with our NCC DA & CDC checklist.
- Watch parallel approvals — Sydney Water building-over constraints, bushfire BAL, and coastal SEPP issues often stack with flood controls (Sydney Water BOAA guide).
What documents should you prepare for lodgement?
For most flood-affected DAs: survey with spot levels and contours to AHD; architectural plans showing finished floor levels against the FPL; Statement of Environmental Effects addressing cl 5.21 matters; flood impact advice or Flood Impact and Risk Assessment (FIRA) where risk warrants it; evacuation notes for higher-risk or sensitive uses; and engineering for structure and any flood-compatible construction below FPL.
For a CDC attempt on a flood control lot: pathway screen against the current Codes SEPP (or other applicable SEPP); hydraulic engineer or council certification that the development footprint avoids flood storage, floodway, flow path, high hazard and high risk areas; plans demonstrating any mandatory floor levels and flood-compatible materials; and a clear fallback plan if certification fails — usually a DA.
giantA coordinates these packages for residential and multi-dwelling work across Greater Sydney so pathway choice and floor levels are settled before documentation freezes.
FAQ: Flood planning levels, freeboard and CDC in NSW
Is freeboard always 500 mm in NSW?
No. Freeboard is adopted through local flood studies and FRM plans. Many councils use figures around 300–500 mm for particular flood types, but you must read the FPL for your site from council flood information — not a statewide default.
Does a flood notation on a Section 10.7 certificate ban all building work?
No. It signals that flood-related development controls may apply. You still need to confirm the mapped flood function, FPL and pathway (exempt / CDC / DA) before designing.
Can I use CDC if only part of my lot floods?
Possibly, if the SEPP pathway remains available and a council or hydraulic engineer certifies that the part of the lot used for the development is not flood storage, floodway, flow path, high hazard or high risk. Partial inundation elsewhere on the title does not automatically unlock CDC.
What is the difference between the flood planning area and the PMF?
The flood planning area is the area where flood-related planning controls generally apply (tied to the FRM Manual definition). Land between the FPA and the PMF may still carry flood-related development controls for some uses — and must be disclosed on planning certificates when applicable — with optional LEP clause 5.22 Special flood considerations for sensitive or hazardous development.
Who sets the flood planning level for my house?
Your local council, through flood studies and floodplain risk management planning, applied via LEP/DCP and certificates. State manuals and guidelines frame how councils should set residential FPLs; they do not replace the local number for your lot.
Should climate change be considered in residential flood design?
Yes for DAs under clause 5.21(3)(a) — the consent authority must consider the impact of the development on projected changes to flood behaviour as a result of climate change. Ask your flood engineer how climate scenarios are treated in the current council study.
Need approvals-ready documentation for a flood-affected NSW site? Contact giantA. We prepare residential and Class 2 design packages across Greater Sydney with early pathway screening, survey coordination and council-ready drawings.
This article is general information for NSW homeowners, builders and designers. It is not legal advice or a site-specific flood assessment. Confirm the current Standard Instrument clause 5.21, Codes SEPP / related SEPPs, your council’s flood study and DCP, and advice from a suitably qualified hydraulic engineer before acting. Cited NSW Government sources researched 10 September 2026.