Flood-prone area: what it means on a build site in NSW

TL;DR

A site is flood prone when it falls within the Flood Planning Area (FPA), defined as land below the Flood Planning Level (FPL): the 1% AEP (1-in-100-year) flood level plus a freeboard of typically 0.5 m above that level. In NSW, flood status is disclosed on the Section 10.7 planning certificate: if the certificate flags a “flood control lot”, flood-related development controls apply. The controls live in the council DCP: minimum floor levels at or above the FPL, restrictions on fill and fencing in flow paths, and a Flood Management Report for any DA on Medium or High Flood Risk land. CDC (complying development) is still available on flood control lots if the SEPP Codes 2008 standards are met, but High Flood Risk land almost always tips into DA. The Flood Risk Management Manual 2023 (NSW) is the current technical reference for councils; it replaced the 2005 Floodplain Development Manual.

When you do this

Check flood status before design starts: before pricing the job, before DA or CDC lodgement, and before signing a contract with a client. Late discovery changes the floor level, adds a Flood Management Report fee to the DA, and can force a full redesign of ground-floor habitable space.

Trigger	What to check
Pre-design / site due diligence	Section 10.7(2) certificate: flood control lot flag, flood planning area, PMF zone
DA lodgement on flood control lot	Flood Management Report required for Medium or High Flood Risk Precinct
CDC application on flood control lot	Engineer’s flood certificate (SEPP Codes 2008 Housing Code clause 3.5) required
Building permit / CC	Floor level set at or above the Flood Planning Level from council’s flood study

Key definitions

Flood-prone land: any land susceptible to inundation by the Probable Maximum Flood (PMF). Development controls only apply to the Flood Planning Area (below the FPL), not the full PMF envelope.

Flood Planning Level (FPL): the 1% AEP flood level plus freeboard (typically 0.5 m for residential). Sets the minimum floor level for habitable rooms. Site-specific FPL in metres AHD is in the council’s flood study (verified 2026-05-09: NSW Flood Risk Management Manual 2023).

Flood Planning Area (FPA): all land below the FPL. Subject to flood-related development controls under LEP clause 5.21. Corresponds to the Medium Flood Risk Precinct.

Flood Risk Precincts (verified 2026-05-09: NSW DPE Flood-Prone Land Package):

Precinct	Definition	Typical control
Low	Between FPA and PMF extent	Clause 5.22 (33 councils opt-in); sensitive/hazardous uses only
Medium	Within the FPA (below the FPL)	Flood Management Report with DA; floor at or above FPL
High	Within FPA, high hydraulic hazard or evacuation difficulty	DA required; CDC rarely available; shelter-in-place refuge may apply

Steps

1. Get the Section 10.7 planning certificate

Order a Section 10.7(2) certificate via the NSW Planning Portal before design starts. Under the EP&A Regulation 2021, the certificate must state whether the land is within the flood planning area or between the FPA and the PMF, and whether flood controls apply. If either flag appears, the site is a flood control lot and DCP controls apply (verified 2026-05-09: NSW Planning Portal, Section 10.7 Service).

2. Obtain council’s flood map

Since 2021, flood maps sit in council flood studies (attached to DCPs) rather than in the LEP. Request the flood study from council to confirm the site’s FPL elevation (metres AHD), its flood risk precinct (Low / Medium / High), and any floodway or overland flow path overlay.

3. Check whether the work is CDC-eligible

Complying development (CDC) is available on flood control lots if the SEPP (Exempt and Complying Development Codes) 2008 standards are met. For a new dwelling on a flood control lot under the Housing Code, clause 3.5 requires an engineer’s flood certificate confirming the proposed floor levels comply. Sites in High Flood Risk Precincts, floodways, or where safe evacuation cannot be demonstrated almost always fail CDC eligibility and must go via DA.

(verified 2026-05-09: SEPP (Exempt and Complying Development Codes) 2008, NSW Legislation)

4. Prepare the Flood Management Report (if DA)

Medium or High Flood Risk Precinct DAs require a Flood Management Report from a hydraulic engineer. It must cover: floor levels, structural soundness, car parking and fencing, emergency evacuation, and overland flow impacts. For High Flood Risk land at Flood Life Hazard H3+, the report must show a safe evacuation route or a shelter-in-place refuge (minimum 2 m² per person above PMF level) (verified 2026-05-09: Northern Beaches Council, Guidelines for Development on Flood Prone Land).

5. Set the floor level at or above the FPL

All habitable rooms must sit at or above the site’s FPL elevation (from the flood study, in metres AHD). Non-habitable areas (garage, storage) may be permitted below the FPL under DCP conditions but must be flood-compatible construction. Some councils apply an additional height above the base FPL for climate change; check the DCP flood chapter.

6. Manage overland flow path constraints

Check the DCP and flood study for any overland flow path overlay before designing site works. DCPs typically prohibit fill or retaining walls that redirect flow paths, fencing that blocks water, and impermeable hard-stand that concentrates runoff onto neighbouring lots. Redirecting overland flow is a legal liability.

7. Note BASIX on flood-prone sites

BASIX is required for new dwellings and additions over $50,000. BASIX does not add flood-specific requirements; flood controls come from the DCP and LEP clause 5.21. Where habitable space sits close to the FPL, flood-adapted design (raised floor, sub-floor ventilation) can interact with BASIX thermal targets. Involve the designer early.

Documents needed

Document	Source	Purpose
Section 10.7(2) planning certificate	Council / NSW Planning Portal	Confirms flood control lot status and applicable controls
Council flood study / flood map	Council website or request	FPL elevation, precinct classification, floodway
Council DCP flood chapter	Council website	Site-specific floor level, fencing, fill controls
Flood Management Report	Hydraulic engineer (your appointment)	DA lodgement requirement for Medium/High precinct
Engineer’s flood certificate	Hydraulic engineer	CDC lodgement requirement for flood control lots

Common holds

Hold	Cause	Fix
Floor level non-compliant	Ground-floor slab below FPL	Raise slab, use platform floor, or redesign for non-habitable use at ground
Overland flow path blocked	Site earthworks or retaining wall in mapped flow path	Redesign earthworks, use permeable treatments, add culvert or swale
Flood Management Report missing	Overlooked at DA lodgement	Commission hydraulic engineer; budget 3 to 8 weeks for a standard residential report
CDC refused on flood grounds	High Flood Risk Precinct or floodway	Lodge DA instead; include Flood Management Report
Referral delay	Council seeking RFS or SES referral for High Flood Risk or PMF zone work	Pre-DA meeting with council to identify referral triggers early

References

NSW Flood Risk Management Manual 2023, NSW Environment and Heritage (verified 2026-05-09)
Flood-Prone Land Package, NSW DPE (verified 2026-05-09)
Local Government Act 1993 (NSW) s 733 (verified 2026-05-09)
SEPP (Exempt and Complying Development Codes) 2008, NSW Legislation (verified 2026-05-09)
Section 10.7 Planning Certificate Service, NSW Planning Portal (verified 2026-05-09)
Guidelines for Development on Flood Prone Land, Northern Beaches Council (verified 2026-05-09)