Finance question
Can I get a loan to build a duplex as a first-time developer?
Yes, often. If you will live in one side or keep both, many banks write a duplex as a residential construction loan with a 10 to 20% deposit on the land plus the building contract, and land equity can count as that deposit. Selling on completion is a different and harder loan for a first project, subject to lender assessment.
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The short answer
Keep it and you borrow like a homeowner. Sell it and you borrow like a developer.
The first thing a lender asks is what happens on completion. If you will live in one side or keep both, most major banks write a duplex as a residential construction loan. In our duplex cost guide that means a 10 to 20% deposit on the land plus the fixed price building contract, land equity counting as deposit, a valuation of the finished pair, and progress draws at slab, frame, lock-up, fixing and completion. Rent from the second dwelling counts at 70 to 80% when the bank tests your serviceability (duplex development cost guide). It is the same process as building a home, which is why it suits a first project.
Sell on completion, or borrow through a company or trust, and it becomes a development facility. Major banks rarely look below about $10 million of cost, so a duplex goes to non-bank and private lenders at 70 to 80% of cost or 65 to 75% of value. Until the titles register the valuer prices the pair as one property at a 10 to 20% discount, and the facility is capped near 65% of that with no presales, or 70 to 75% with one side presold. A gap can be filled by a second mortgage or by cross-securing the family home. On this path lenders weigh your experience and your builder's record far more heavily, so a first-timer often does better by planning to hold.
The profit decides whether either path is worth it. On the guide's knock-down-rebuild, a 700 m2 Brisbane lot bought for $1,000,000 and built at $2,500 per square metre, total cost is about $2.51 million and selling both sides returns only 1.3% on cost. Land at $800,000 and a build at $2,300 per square metre lifts that to 14.6%, and a Melbourne builder's rule quoted in the guide is that end value must clear total cost by at least 15% before a dual occupancy is worth starting. Ventas is a broker across 40+ lenders, and there is no upfront fee to you; the lender pays us on settlement.
Do you qualify?
What a lender looks at on a first duplex.
Land or equity
The block you own, or equity in a home, counts toward the deposit.
A fixed price contract
A licensed builder's quote, plans and your DA or CDC status.
A feasibility
Costs, end values and a margin that survives a price drop.
A clear intention
Live in one side, keep both or sell: each is a different loan.
Why the keep path suits a first project
A home-style loan
Progress draws on a residential construction loan, not a development facility.
Land counts
Equity in the block can cover the deposit.
Rent helps
The second dwelling's rent counts at 70 to 80% for serviceability.
A worked example
A couple buys a 700 m2 Brisbane lot for $1,000,000 and signs a $900,000 fixed price contract for two sides, to keep. At a 10 to 20% deposit on land plus contract ($1.9 million) they need $190,000 to $380,000, which equity in their current home can cover. Sold instead, the same job costs about $2.51 million and a non-bank lender would fund around $1.75 million. Illustrative only.
Common questions
Frequently asked questions
Do I need development experience to get a duplex loan?
Often not on the keep path, where most banks assess you as a home builder on income, deposit and a fixed price contract. On the sell path lenders weigh your experience and your builder's track record far more heavily.
Can I use the equity in my home as the deposit?
Commonly, yes. Land equity counts as deposit on the keep path, and on the sell path a funding gap can be covered by a second mortgage or by cross-securing the family home, subject to lender assessment.
Will a lender fund the build if I plan to sell both sides?
Yes, but usually not a major bank. Banks rarely look below about $10 million of cost, so a sell-on-completion duplex normally goes to non-bank or private lenders at roughly 70 to 80% of cost, with the pair valued at a discount until the titles register.
How much does it cost to build a duplex?
The guide puts 2026 build rates at about $2,300 to $3,500 per square metre excluding GST, so $415,000 to $630,000 per 180 square metre side before land, demolition and subdivision.