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When comparing new-build options, the headline price tag rarely tells the full story.
You might look at a completed, turnkey townhouse priced at $900,000, and then see a vacant section nearby where a builder estimates you could build a similar home for a combined total of $850,000.
At first glance, building from scratch appears to offer an instant $50,000 saving. But is it genuinely cheaper once the front door key is in your hand?
To work that out, you have to look beyond the initial contract figure and calculate the holding costs. Both options can be secured with a 10% deposit under Reserve Bank new-build rules, so the choice does not come down to equity. It comes down to what happens to your cash flow while the house is actually being built.
Here is a breakdown of how both options work from a banking perspective, what happens to your outgoings during the build, and how to determine which path best suits your household budget.
The turnkey route: paying for certainty
With a turnkey property, you pay an initial deposit (typically 10%) when signing the contract, and you pay nothing further until the home is completely finished, the Code Compliance Certificate (CCC) is issued, and the title is transferred.
During the entire construction period, you do not pay a single cent of mortgage interest on the build. You simply continue paying your usual rent or living expenses until settlement day.
Because the developer funds the project from start to finish, they carry the financial load: the land finance, the staged construction interest, council consent fees, and the commercial risk of material or labour price increases.
Why turnkeys appear more expensive
To cover those holding costs and compensate for project risk, the developer builds a margin into the final sale price.
When you buy a turnkey, you are effectively paying a premium for cash flow certainty. You know your exact purchase price on day one, and you avoid the financial strain of servicing a growing mortgage while still paying rent elsewhere.
Construction loans: understanding the overlap
When you choose a construction loan with progress payments, you buy the land and enter into a building contract with a builder.
Because Reserve Bank LVR rules exempt new residential construction, securing a construction loan with a 10% deposit is very common across major New Zealand banks, provided you have a fixed-price contract in place.
Because you are taking on the project directly rather than buying through a developer, the initial paper cost is often lower. However, you take over all the holding costs that a developer would otherwise carry.
How progress payments work
A construction loan does not draw down all at once. It is released in stages as work is completed and verified:
- Land settlement: The loan for the section draws down first.
- Foundations/Slab: First construction drawdown once the concrete is poured.
- Framing: Second drawdown once the frame and trusses are standing.
- Lock-up: Third drawdown once cladding, roofing, and exterior joinery are completed.
- Interior linings and fit-out: Fourth drawdown for plastering, painting, kitchen, and bathrooms.
- Practical completion: Final drawdown upon issue of the Code Compliance Certificate.
The overlap cost
What the bank looks for in a 10% construction loan
While 10% deposit construction lending is standard practice, credit teams still apply sensible guardrails to manage risk:
- Fixed-price contract: The bank will require a comprehensive, fixed-price building contract backed by an accredited guarantee (such as Master Build or Certified Builders).
- Cost overrun buffer: Banks typically require a 10% to 15% contingency reserve in your overall funding budget to ensure you have breathing room if unexpected site works or variations arise.
- Servicing capacity: Under affordability rules, the bank must be satisfied that your income can comfortably service your rent alongside the peak construction interest payments.
Comparing the real costs side-by-side
To understand whether the potential equity gain of a construction loan outweighs the cash flow certainty of a turnkey, you need to model both scenarios against your weekly income and timeline.
Use the interactive tool below to enter your project numbers, see how much cash leaves your account during each build phase, and compare the estimated final cost of each option.
Control versus certainty: how to decide
Once you account for holding costs—the rental overlap, land loan interest, and progressive build payments—the total out-of-pocket cost of managing your own build often narrows the gap with a turnkey package.
Neither approach is inherently superior; they simply structure the exact same holding costs differently:
- With a turnkey, holding costs are packaged into the purchase price and funded through your long-term mortgage once you move in.
- With a construction loan, you fund those holding costs out of your everyday cash flow during the build, which keeps your final mortgage balance lower.
A construction loan may suit you if:
- You want complete design control over the floor plan, section choice, and interior specifications.
- Your current household cash flow comfortably supports paying your current rent alongside escalating mortgage interest payments.
- You are comfortable managing building milestones, progress valuation sign-offs, and council paperwork.
A turnkey package may suit you if:
- Your budget cannot comfortably absorb paying rent and a mortgage simultaneously.
- You prioritise price certainty and want a fixed, hands-off process.
- You are happy to choose from developer-curated colour palettes and floor plans in exchange for lower day-to-day financial stress.
Structuring your new-build finance
Whether you decide on a turnkey package or manage your own build contract, getting the lending structure right from the outset is essential to keeping the project on track.
At Home Loan Factory, we help buyers compare holding costs, review building contract finance clauses, and ensure the bank's drawdown schedule matches your builder's payment milestones.
Book a Free New Build Strategy Session with Home Loan Factory
Frequently asked questions
Can I get a construction loan with a 10% deposit in New Zealand?
Yes. Under Reserve Bank of New Zealand lending rules, new residential construction is exempt from standard LVR restrictions. Major trading banks routinely offer construction loans with a 10% deposit, provided you have a fixed-price building contract from an approved builder.
What is the main difference between a turnkey and a construction loan?
With a turnkey property, you pay a deposit upfront and do not make any mortgage payments until the house is fully completed with a Code Compliance Certificate. With a construction loan, you purchase the section first and make staged progress payments to the builder (and pay interest to the bank on the drawn-down balance) as construction milestones are reached.
Why does a turnkey property cost more on paper?
The developer takes on all financial risk, land holding costs, council fees, and loan interest during construction. Those overheads and project risks are factored into the final contract price, providing the buyer with complete price and cash flow certainty.
What is an overlap cost during a build?
An overlap cost refers to paying your regular rent or current mortgage outgoings while simultaneously paying interest on the land loan and progressive construction draws as your new home is being built.
