There is no "triplex" category in NSW planning law. Three homes on one lot are approved as a type of multi dwelling housing, or sometimes as a manor house, and which route fits comes down to the design, the zoning and the site itself.
Work out what you are building
Start by matching the design to the planning terms:
- Terraces. At least three attached homes on one lot, each with ground level access, none above another, facing and generally aligned along a public road.
- Multi dwelling housing. Three or more homes on one lot with ground level access, which can include layouts where homes sit behind each other along a driveway.
- Manor house. Three or four homes in a building no taller than two storeys, with at least one home above another.
Terraces and most townhouse layouts are Class 1a under the building code. A manor house is Class 2, so its certifier needs a registration that covers Class 2 work. Our guide on When is a triplex still Class 1? Classification explained explains the difference.
The CDC route: terraces under the code
The state's Low Rise Housing Diversity (LRHD) Code allows terraces to be approved as complying development. The land must be zoned R1, R2, R3 or RU5, and the LEP must permit the development. If the LEP sets no minimum lot size, the code applies a default of 600 m². Homes are limited to one or two storeys. A registered architect or accredited building designer must also sign off a design verification statement.
The usual complying development exclusions apply, including heritage items, heritage conservation areas and environmentally sensitive land. If the design misses a single standard, the CDC route closes.
The DA route and the low and mid-rise housing changes
Layouts that do not front a public road, sites with constraints, and designs that miss a code standard are lodged with council as a DA. After consent, a construction certificate must be issued before building starts.
Since 28 February 2025, the state's low and mid-rise housing policy has permitted terraces and multi dwelling housing, with consent, on R2 land within mapped areas near selected town centres and stations. In those areas, the state sets non-discretionary standards that a council cannot use to refuse a compliant DA:
- multi dwelling housing: minimum lot 600 m², minimum width 12 m, floor space ratio up to 0.7:1, height up to 9.5 m
- terraces: minimum lot 500 m², minimum width 18 m, floor space ratio up to 0.7:1, height up to 9.5 m
Some hazard affected land, including bushfire prone and certain flood prone land, is excluded. The NSW Pattern Book also offers pre-designed options for these areas.
After approval
With the approval in hand, whichever route it came through, the next steps look much the same:
- Appoint a principal certifier and give notice before work starts.
- Complete the mandatory critical stage inspections for each home.
- Gather certificates for fire-resisting walls, waterproofing, structure and BASIX.
- Obtain an occupation certificate before the homes are occupied.
- Arrange any subdivision through the surveyor and subdivision certifier.
Test the design first
Lot width, frontage and the way the homes face the street often decide the route. Have the concept checked through our plan assessment service before detailed design. Learn more on our triplex page or request a quote.
Local help across NSW
CertifiBuild certifies Class 1 and Class 10 work in 39 council areas. Local rules on these council pages are a good place to start: Burwood Council, Ku-ring-gai Council, Hawkesbury City Council, Wollongong City Council, Randwick City Council, Bayside Council.
Suburb pages with local planning notes: Burwood, East Killara, Ebenezer, Enfield, Horsley, Killara, Kingsford, Kingsgrove, Lapstone, Megalong Valley. You can also browse every service area.
Sources
- Codes SEPP Part 3B, Low Rise Housing Diversity (LRHD) Code page, NSW Planning Portal
- Low and mid-rise housing policy key provisions summary, NSW Department of Planning
- February 2025 announcement on low and mid-rise housing, NSW Department of Planning