How are seawalls designed, approved and repaired in NSW?

Seawall cracked, leaning or losing rock? Get a quote or call 02 4326 9026, and send photos of the wall, its base and both ends.

What is a seawall?

A seawall is a structure that separates land from water, protects the land from erosion by waves and currents, and holds back the fill behind it. That is the definition used by Manly Hydraulics Laboratory (MHL), the NSW Government's specialist coastal adviser. The NSW Environmentally Friendly Seawalls guide counts both sloping rock revetments and solid vertical walls as seawalls.

The Coastal Management Act 2016 classes seawalls, revetments, groynes and beach nourishment as coastal protection works. NSW Planning's fact sheet says these works protect assets during a storm of a specified size, need ongoing maintenance, and can cause erosion or accretion elsewhere. For how erosion itself affects homes, see our guide to coastal erosion on the Central Coast.

What types of seawall are there?

Seawalls are either sloping, like rock revetments, or vertical, and composite designs combine the two. Central Coast Council's Open Coast Coastal Management Program (CMP) shows local examples: a sandstone block seawall at Terrigal Haven, a rock seawall at Patonga and a rock revetment at the Avoca Beach surf club.

MHL's 2021 concept study for Wamberal Beach compared five options; the two basic types were (levels relative to the Australian Height Datum, AHD):

Wamberal concept (MHL, 2021)	Sloping rock revetment	Vertical seawall
Construction	Two layers of basalt or sandstone armour rock on a 1V:1.5H slope	Precast concrete panels between H-columns, on piles, with a sheet pile toe
Toe level	-1 m AHD, with a berm scour apron	-3 m AHD
Width across the beach	About 23 m	About 1 m
Advantages	Lower cost; conventional, non-rigid design	Smallest footprint; low beach encroachment
Disadvantages	Wide footprint; reduced beach width; higher maintenance	Moderate to high cost; vertical drop after storms, a safety concern; more reflected wave energy in storms, limited in time and extent
Capital cost estimate	About $18,400 to $19,500 per metre	About $25,000 per metre
Maintenance estimate, whole beach	About $250,000 to $265,000 a year	About $34,000 a year

These are preliminary 2021 estimates for a structure about 1,360 m long, excluding sand nourishment. The CMP stresses the options are concepts only.

How is a seawall engineered?

A seawall is engineered to survive a chosen design storm over a set design life, with its toe below the expected scour and its crest set to limit wave overtopping. The Wamberal Beach Engineering Design Requirements, prepared by MHL and adopted by Central Coast Council in October 2022, require:

• Design life and storm: at least 50 years, with a minimum design average recurrence interval (ARI) for failure of 500 to 2,000 years.
• Waves: the concept 100-year ARI storm has an 8.7 m offshore significant wave height (3-hour storm) and an ocean water level of +1.46 m AHD, excluding wave setup and sea level rise.
• Toe and scour: a design scour level no higher than -2 m AHD unless studies support another. MHL notes that toe failure from undermining is the most common cause of failure of coastal protection works that are not properly designed.
• Crest: set by a qualified engineer for wave runup and overtopping, and confirmed by physical modelling unless adequate factors of safety are shown.
• Ground: a geotechnical investigation with at least three test pits along the alignment.
• Materials: rough, angular armour rock, individually placed with at least three points of contact. Concrete and steel follow AS 4997-2005, which Standards Australia replaced with AS 4997:2026, Maritime structures, in May 2026.
• Drainage: return flows from overtopping and rainfall. MHL notes groundwater pushes on the back of a seawall unless drainage relieves it.
• Ends: terminal end controls to protect neighbouring properties from end erosion, where storm waves get behind an exposed end of a seawall and can collapse it from the landward side.

Do you need approval to build a seawall in NSW?

Yes. Under section 2.16(1) of State Environmental Planning Policy (Resilience and Hazards) 2021 (the Resilience and Hazards SEPP), anyone other than a public authority may build coastal protection works only with development consent.

On land directly next to, or under the waters of, the open ocean, an estuary entrance or the entrance of a coastal lake open to the ocean, a private seawall is regionally significant development under Schedule 6 of State Environmental Planning Policy (Planning Systems) 2021, unless the certified CMP identifies it. Since 16 January 2026, new regionally significant applications on the Central Coast are determined by the Central Coast Local Planning Panel on behalf of the Hunter and Central Coast Regional Planning Panel. Council is the consent authority for other private coastal protection works.

Section 27 of the Coastal Management Act 2016 bars consent unless the decision-maker is satisfied that, over the life of the works:

• they won't unreasonably limit public access to, or use of, a beach or headland;
• they won't pose a threat to public safety;
• consent conditions secure the works' maintenance, and restoration of the beach if the works increase erosion.

Section 2.12 of the SEPP adds a further test: the consent authority must be satisfied the development is not likely to cause increased risk of coastal hazards on that land or other land.

A public authority, such as a council, may work without consent on works identified in the certified CMP, beach nourishment, sandbags for up to 90 days, or routine maintenance and repairs. From 4 May to 1 June 2026, NSW Planning exhibited proposed changes that include extending consent-free sandbag placement by public authorities from 90 days to up to a year, and clarifying where coastal protection works are regionally significant. Confirm the current rules before you lodge.

What are the seawall rules on the Central Coast?

On the Central Coast, a private seawall needs development consent and is assessed against Council's certified Open Coast CMP and Chapter 3.2 of the Central Coast Development Control Plan 2022 (DCP).

• The CMP. Certified on 17 June 2026, it covers about 80 km of open coast from Box Head (Killcare) to Snapper Point (Budgewoi), but not The Entrance channel or Tuggerah Lakes. Owners may still lodge a development application (DA) for works on their own land, assessed on its merits. Citing the Coastal Crown Land Guidelines, it says private structural coastal protection works on the open coast should be wholly within the property they protect.
• The DCP. In the northern area (the former Wyong local government area), seawalls protecting existing private assets from coastal recession are considered on merit. In the southern area (the former Gosford local government area), structures in a coastal hazard area must not increase any coastal hazard and must be set back as far landward as practicable.
• Wamberal. The design requirements put the seawall as far landward as possible, on private property where possible, built, owned and maintained by the owners. In June 2026 the Hunter and Central Coast Regional Planning Panel refused all three DAs for a terminal protection structure there. The CMP's strategy is sand nourishment underpinned by a rock revetment or hybrid rock revetment.
• Ministerial authorisation. Under section 68 of the NSW Reconstruction Authority Act 2022, the Minister can authorise development without planning approval in a declared reconstruction area affected by a disaster, when the Reconstruction Authority's chief executive asks. At Council's request it was used for temporary coastal protection works at The Entrance North in 2025, and in July 2026 Council lodged an updated request for sand nourishment underpinned by a sloping rock revetment at Wamberal.

How is a damaged seawall repaired?

A damaged seawall is repaired by inspecting it to find what failed, then replacing displaced armour or rebuilding damaged sections to an engineered design. The Wamberal requirements and the CMP point to these steps:

1. Inspect after major storms. For the Wamberal rock revetment concept, the CMP expects visual inspections after storms, with armour topped up or replaced only if displaced.
2. Find the cause, such as undermining at the toe, erosion behind the ends or poor drainage.
3. Follow the maintenance plan. At Wamberal, a qualified coastal engineer prepares it and Council approves it.
4. Certify structural repairs, and send Council a copy of the certification.

Only public authorities may carry out routine repairs without consent. NSW Planning's fact sheet says private owners need development consent for coastal protection works, short or long term, so ask Central Coast Council before repairing a private seawall.

When to call a structural engineer

Call a structural engineer when a seawall on your land is cracked, leaning, undermined or losing rock, or when you are preparing a DA for one. Typical triggers:

• after a storm, armour rock has moved, the toe is exposed or the ends have eroded;
• concrete or steel in an older wall is cracking or corroding;
• you are buying a waterfront home protected by a seawall;
• your DA is in a southern coastal hazard area, where the DCP asks for coastal, geotechnical and structural engineering reports.

Our structural design and consultation service covers retaining wall drawings and structural remedial design, and our inspection reports include retaining wall inspections.