Building in Wollongong and the wider Illawarra means dealing with three things at once: the escarpment, bushfire prone land and slope. Most residential DAs from Helensburgh down to Dapto are assessed under Wollongong LEP 2009 and Wollongong DCP 2009, and the reports that decide the outcome are usually the geotechnical assessment, the bushfire assessment and the stormwater design, not the architecture. If you understand which of those three constraints touches your block before you design, the DA is far more predictable.
Key takeaways
- Wollongong LEP 2009 and Wollongong DCP 2009 are the controls for most of the city, with Shellharbour LEP 2013 and Shoalhaven LEP 2014 applying further south.
- Land along the Illawarra Escarpment is largely mapped as bushfire prone, so a Bushfire Assessment Report under Planning for Bush Fire Protection 2019 is usually needed.
- Steep sites in suburbs like Thirroul, Austinmer, Mount Keira and Figtree commonly need a geotechnical report addressing landslip risk before council will assess the DA.
- Driveway gradients, cut and fill, retaining walls and overland flow paths are where steep-site designs most often fail the DCP.
- From 1 July 2024 dual occupancies are permissible in R2 zones across NSW, but the site constraints in the Illawarra still decide whether a duplex actually fits.
The three constraints that shape almost every Illawarra DA
The Illawarra is a narrow coastal strip. The escarpment rises steeply to the west, the ocean sits to the east, and most of the housing is on the slopes and creek flats in between. That geography drives three constraints.
- Escarpment and environmental zoning. The foothills above suburbs like Bulli, Woonona, Balgownie, Mount Pleasant, Mount Keira, Mount Kembla and Farmborough Heights carry conservation zones and escarpment controls under Wollongong LEP 2009.
- Bushfire prone land. The vegetated escarpment means that a large share of blocks backing onto bushland, and many that do not, are mapped as bushfire prone on council’s map. That triggers Planning for Bush Fire Protection 2019.
- Slope and landslip. A lot of the northern suburbs and the Mount Keira and Figtree foothills sit on steep colluvial slopes. Council treats these as landslip risk areas and asks for a geotechnical assessment prepared in line with the geotechnical chapter of Wollongong DCP 2009.
Flatter, better-serviced land sits closer to the rail corridor (Thirroul, Bulli, Corrimal, Towradgi, Fairy Meadow, North Wollongong, Coniston, Unanderra and Dapto stations on the South Coast Line) and out on the Dapto and Horsley flats and the West Dapto release area.
Bushfire: what Planning for Bush Fire Protection 2019 asks of a house or duplex
If any part of the lot is on the Bush Fire Prone Land Map, the DA must show compliance with Planning for Bush Fire Protection 2019. For a new dwelling, alterations and additions or a dual occupancy this normally means:
- A Bushfire Assessment Report that identifies the vegetation type, the slope under that vegetation and the distance from the building to it.
- A Bushfire Attack Level (BAL) for each elevation, from BAL-LOW through BAL-12.5, 19, 29, 40 and BAL-FZ (Flame Zone).
- Construction to AS 3959:2018 for the assessed BAL.
- An Asset Protection Zone (APZ) around the building, maintained as managed land.
On an infill lot in Thirroul or Austinmer the BAL is often driven by escarpment forest 40 to 100 metres away, and the APZ then competes with the private open space and landscaped area the DCP wants. We usually push the BAL down with distance before leaning on construction upgrades, because BAL-40 and Flame Zone construction costs are significant.
Subdivision on bushfire prone land is a different matter. A new residential lot is integrated development under s4.46 of the Environmental Planning and Assessment Act 1979 and needs a Bush Fire Safety Authority from the NSW Rural Fire Service. Their building on bush fire prone land page sets out what the RFS looks at.
Steep sites: the geotechnical report comes first
Wollongong is one of the few NSW councils with long-standing landslip mapping and a geotechnical DCP chapter. On a mapped site the council will not assess the DA properly until it has a geotechnical assessment that:
- Confirms the landslip risk category for the site and the proposed works.
- Sets out foundation, excavation and retaining wall recommendations.
- Deals with groundwater and subsoil drainage, which is often the real cause of instability on the escarpment slopes.
Commission the geotech before the architect fixes the floor levels. A recommendation to limit cut depth or keep fill off the downslope side can change the whole design, and it is far cheaper to hear that at concept stage.
The DCP controls that bite on slopes
Wollongong DCP 2009 handles residential design in its general residential chapter, and these are the controls we see steep-site designs fail most often:
| Control | Why it matters on a steep Illawarra site |
|---|---|
| Cut and fill limits | The DCP limits the depth of cut and height of fill around a dwelling. |
| Retaining wall height and setback | Tall boundary retaining walls are a common refusal reason; stepping the walls helps. |
| Building height | Wollongong LEP 2009 measures height from existing ground, so a house that steps down a slope can exceed the standard at the low corner and need a Clause 4.6 request. |
| Driveway gradient | AS 2890.1:2004 sets maximum gradients and transition lengths. On a 1 in 4 block a compliant driveway can consume much of the frontage. |
| Overland flow and stormwater | Discharge must go to a legal point. Downslope lots often need an easement or a pump-out, both of which need to be shown in the DA. |
Where a numeric control is exceeded because of slope, a written Clause 4.6 request that shows the exceedance comes from topography rather than bulk is the right tool. There is no guarantee, and the request has to be properly reasoned.
Where dual occupancies and small subdivisions sit in the Illawarra
Dual occupancies have been popular in the flatter suburbs (Corrimal, Fairy Meadow, Gwynneville, Unanderra, Dapto, Horsley and Kanahooka) for years. From 1 July 2024 the State Government’s Low and Mid-Rise Housing changes make dual occupancies and semi-detached dwellings permissible in R2 Low Density Residential zones across NSW, which removes a permissibility barrier in parts of the city where the LEP land use table previously did not allow them. Permissibility is only the first step. Minimum lot size for a dual occupancy, whether Torrens subdivision is allowed, and the frontage, parking and landscaped area controls all still come from Wollongong LEP 2009 and Wollongong DCP 2009, so check the current figures for your lot before you buy.
Complying development under the Low Rise Housing Diversity Code is often unavailable on Illawarra sites because of bushfire, landslip or environmental mapping, so a DA with a Statement of Environmental Effects is the normal pathway. Further south, Shellharbour LEP 2013 and Shoalhaven LEP 2014 have their own dual occupancy provisions, and the Illawarra Shoalhaven Regional Plan 2041 directs most new greenfield housing to West Dapto, Calderwood and Tullimbar rather than the escarpment.
Check these before you buy an Illawarra block
Zoning and minimum lot size, the Bush Fire Prone Land Map, landslip mapping, the flood planning area on the creek flats between Dapto and Albion Park, escarpment and scenic overlays, heritage listings in older parts of Wollongong, Thirroul and Bulli, and the location of sewer and stormwater. Most of these appear on the s10.7(2) certificate or the NSW Planning Portal spatial viewer, and a development due diligence report pulls them together into a clear picture of what can realistically be built before you commit.
Frequently asked questions
Do I need a bushfire report to build a house in Wollongong?
Only if any part of your lot is on the Bush Fire Prone Land Map. A large share of lots near the escarpment are. The report assesses the Bushfire Attack Level and sets the construction standard under AS 3959:2018 and the Asset Protection Zone you must maintain.
What is a geotechnical report and when does Wollongong Council ask for one?
It is an engineer’s assessment of slope stability, foundations, excavation and drainage. Council asks for it on land mapped as a landslip risk area under Wollongong DCP 2009, and on any site where the proposed cut, fill or retaining walls could affect stability.
Can I build a duplex on a steep block in the Illawarra?
Often, yes, but the design has to step with the slope to keep cut, fill, wall heights and building height within Wollongong LEP 2009 and DCP 2009. Check the minimum lot size for a dual occupancy first, then get the geotechnical and bushfire advice before the design is fixed.
URBA prepares Statements of Environmental Effects, Clause 4.6 requests and due diligence reports for houses, duplexes and small subdivisions across the Illawarra, and we coordinate the bushfire, geotechnical and civil consultants a steep or escarpment site needs. Our Wollongong town planning page explains how we work with the council, or you can request a fee proposal for your site.