If you own a block big enough for two homes, the questions come in a predictable order. What is the difference between a dual occupancy, a duplex and a townhouse? What does it cost to build? Do I have to subdivide? How long does it take? Here is how it works in Melbourne in 2026, from a builder who has taken a three-residence development from permit to completion.
The short answer. Dual occupancy means two dwellings on one lot, and a planning permit is required in Victoria's main residential zones. The cost is the construction of both homes plus demolition, site costs, design and permits, subdivision and holding costs. Crowncon builds these as a fixed-price, staged programme, so each home can be finished and sold or held on its own timeline. Construction is priced per square metre, so a 150 m² dwelling runs from about $330,000 to $780,000 depending on finish.
Dual occupancy, duplex or townhouse: what is the difference?
The words overlap, and councils, agents and builders use them loosely. In practical terms:
- Dual occupancy is the everyday term for two dwellings on one lot. They can be attached or detached. The planning scheme itself talks about "two or more dwellings on a lot".
- A duplex is the attached version: two homes sharing a common wall, side by side or one behind the other.
- A townhouse is a dwelling in a row of attached homes, usually multi-storey. Townhouse developments often have three or more dwellings, which brings the Townhouse and Low-Rise Code into play.
The distinction matters because the number of dwellings, whether they are attached and whether you subdivide change the permit pathway, the design and the cost. A rule of thumb: if you are building two, think dual occupancy or duplex; three or more, think townhouses.
How much does it cost to build a duplex in Melbourne?
There is no single number, because a two-dwelling project is several costs stacked together. The table shows the components, using Crowncon's published 2026 figures where they apply to any project on a block with an existing house, and marking the items that depend on your design.
| Cost component | 2026 Melbourne range | What drives it |
|---|---|---|
| Demolition | $15,000–$40,000 | Single or double storey, brick or weatherboard, site access |
| Asbestos removal (pre-1990 homes) | $2,500–$15,000+ | Amount of asbestos, licensed removal and disposal |
| Site costs | $15,000–$80,000+ | Slope, soil type, service connections, access. Two dwellings need two sets of connections |
| Design, permits and reports | $15,000–$40,000 for one home; $30,000–$50,000 for two | Drafting, engineering, soil report, energy rating, planning permit and council fees |
| Planning permit application fee | $1,804.70 (development cost up to $1 million) or $3,980.70 ($1–5 million) | Total estimated cost of the development. Set by the state, so it is the same in every council (2026–27 schedule) |
| Construction, per dwelling | $2,200–$5,500+ per m² | Floor area, design complexity, level of finish, attached or detached |
| Council asset protection permit and bond | $350 permit; refundable bond of $5,000 (works $100,000–$1 million) or $7,500 ($1–5 million) | Kingston’s published figures. Other councils differ. The bond is returned if council assets are left undamaged |
| Subdivision and new titles | About $10,000–$28,000 for a two-lot subdivision: surveyor $5,000–$15,000, town planner $3,000–$8,000, council fees $2,000–$5,000 | Surveyor, council certification, statement of compliance |
| Holding costs while you build | Interest of roughly $5,000–$6,700 a month for every $1 million borrowed (at 6–8 per cent), plus council rates and land tax | Interest, rates and land tax over the programme |
Construction is the biggest line, and it scales with floor area. Using our published 2026 rates of $2,200–$3,400 per m² for a practical, well-built home and $3,400–$5,200 per m² for a quality custom build, one dwelling works out as follows. The floor areas are illustrative, not a statement of what we typically build.
| Dwelling size | Practical ($2,200–$3,400/m²) | Quality custom ($3,400–$5,200/m²) |
|---|---|---|
| 120 m² | $264,000–$408,000 | $408,000–$624,000 |
| 150 m² | $330,000–$510,000 | $510,000–$780,000 |
| 180 m² | $396,000–$612,000 | $612,000–$936,000 |
For a single home, the extras outside the construction contract (site costs, permits, design fees, landscaping, connections and a contingency) usually add $80,000 to $180,000. Budget for the whole project, not just the contract price.
The demolition, asbestos and site figures are the same ones in our knockdown rebuild cost breakdown, because the starting point is the same: a block with a house on it that has to come down. Where a development differs is the multiplier. You pay for demolition and site preparation once, but you pay for two sets of service connections, two sets of finishes and, if you subdivide, the titles.
Want a ballpark on your own block? Our free feasibility check runs your address against Victoria's official planning data and flags the zoning and overlays that will shape the cost.
Knock down and build two: how a development differs from a knockdown rebuild
A knockdown rebuild replaces one home with one new home. A dual occupancy replaces one home with two, which changes three things:
- It needs a planning permit. A single replacement home on a lot that already has a house often doesn't. Two dwellings do, in the residential zones.
- The design is constrained by the block. Garden area, site coverage, setbacks and trees decide how much you can build. Our guide to the minimum land size for dual occupancy in Victoria covers those rules.
- The decision is partly financial. You are weighing one larger home against two smaller ones that can be sold or rented separately.
Can I build a duplex on my land?
Often yes, but it depends on the zone, the lot, overlays, easements, any covenant on the title and the trees. A block that suits a duplex is usually wide enough to fit two dwellings and their driveways within the garden area and coverage limits, and free of a covenant that allows only one dwelling. The land-size guide above walks through each of these, so we won't repeat them here. Start with the title and the zone, not the square metres.
The process, step by step
- Feasibility. Check the zone, overlays, title, easements and trees before you spend on design.
- Design and consultants. A designer or architect, a surveyor, a soil report and an energy assessment.
- Planning permit. Council assesses the application against the Victorian standards. The statutory decision period is 60 days, but multi-dwelling applications that need further information, notice or referral commonly run three to six months. Designs that meet the Townhouse and Low-Rise Code are deemed to comply, and the state government says that can cut assessment times by at least 60 per cent.
- Building permit and fixed-price contract. One price for the programme, agreed before work starts.
- Demolition and site preparation. Old house out, services and drainage for two dwellings in.
- Staged build. Each dwelling is programmed to reach practical completion in turn, so one can be sold or let while the next is finished.
- Subdivision and titles. If you are selling separately, council certification and new titles for each lot.
- Sell or hold. Hand over the keys, or keep both.
Subdivide and sell, or hold and rent?
Two dwellings on one lot and two dwellings on two titles are different projects. If you want to sell one home, you need to subdivide, which needs its own permit and certification, and each new lot has to meet the standards on its own. If you plan to keep both, you can build on one title and decide later. Some owners build both, move into one and let the other. Talk to a conveyancer or accountant about how each path is treated for tax and finance, because the answer depends on your circumstances and we aren't the right people to give it.
A worked example: Lorraine, Langwarrin
Lorraine is our three-residence coastal development in Langwarrin, Frankston. The brief was a staged build in which each residence could be subdivided and sold as it reached practical completion. That meant programming the trades so that one home finished while the next was still under way, rather than holding all three until the last was done.
- Site: Langwarrin, Frankston, three residences
- Approach: staged build, subdivision-ready, sold on completion
See the full Lorraine case study, or read how we approach dual occupancy and multi-dwelling builds in Melbourne.
Planning a development? Let's talk about what's possible on your land. Book a free, no-obligation chat with Tim, or run your address through the free feasibility check first.
Common questions
What is dual occupancy?
Dual occupancy is the everyday term for two dwellings on one lot. They can be attached, like a duplex, or detached. In Victoria a planning permit is required to construct two or more dwellings on a lot in the General Residential, Neighbourhood Residential and Residential Growth zones.
How much does it cost to build a duplex in Melbourne?
The total is the construction cost of both dwellings plus demolition, site costs, design and permits, subdivision and holding costs. Crowncon's published 2026 figures for the shared items are demolition $15,000 to $40,000, site costs $15,000 to $80,000+ and design, permits and reports $15,000 to $40,000. Construction is priced per square metre, from $2,200 to $5,200 for practical to quality custom builds, so a 150 square metre dwelling runs from about $330,000 to $780,000.
Do I need a planning permit to build a dual occupancy in Victoria?
Yes. In the General Residential, Neighbourhood Residential and Residential Growth zones a permit is required to construct or extend two or more dwellings on a lot. Overlays can add further requirements.
What is the difference between a duplex, a dual occupancy and a townhouse?
Dual occupancy means two dwellings on one lot. A duplex is the attached version of that. A townhouse is a dwelling in a row of attached homes, usually multi-storey, and townhouse developments often have three or more dwellings.
Can the two dwellings be sold separately?
Only if the lot is subdivided. Subdividing needs its own permit and certification, and each new lot has to meet the planning standards on its own.
General guidance current at October 2026, drawn from the Victorian planning scheme. Costs are indicative, vary by site and design, and are not a quote. Zone schedules and overlays vary by council and by site, and the rules have been changing. This is not legal, planning, tax or financial advice. Check your specific block with council or a town planner before you commit.
