New Build Construction Loan Calculator (NZ)
Calculate exactly how much you need to budget for your new build, week by week. Unlike buying an existing house, a construction loan is paid out in stages (progress payments) as the builder hits specific milestones. This means your mortgage interest snowballs over time. Use our calculator below to separate your land loan from your build loan and forecast exactly what your floating, interest-only payments will be at every stage of construction.
Construction Cashflow Forecaster
Please rotate your phone sideways (landscape mode) to view the week-by-week cashflow forecaster.
| Build Stage | Invoice Amount | Your Cash Used | Bank Funds Drawn | Total Loan Balance | Weekly Budget required |
|---|
How to Use This Forecaster
To get the most accurate cashflow projection for your new build, follow these steps:
Enter Your Costs: Input your land purchase price (if applicable) and your fixed-price building contract amount.
Input Your Deposit: Enter your total cash deposit. Note: Banks generally require a minimum 20% deposit against the land portion before releasing funds.
Set Your Rates: Enter current market rates. Land is typically set to a standard Fixed Principal & Interest rate, while construction funds are drawn on a Floating Interest-Only rate.
View Your Budget: Scroll through the table to see how your required weekly budget increases as the bank releases more funds to the builder.
How is interest calculated on a construction loan in NZ?
Interest on a construction loan is calculated daily, but you only pay interest on the exact amount of money the bank has released so far, not the total loan limit. Construction funds are typically placed on a floating, interest-only rate until the Code Compliance Certificate (CCC) is issued. Once the build is fully complete, the loan can be converted to a standard fixed interest rate.
How do I manage paying rent and a mortgage at the same time?
The biggest cash flow challenge when building a house is the "rent and mortgage overlap." Because the bank releases funds to your builder in stages (progress payments), your mortgage payment will start small and gradually increase at each milestone. By the time the house is nearly finished, you will be paying your standard rent plus a nearly full mortgage. You must budget carefully for this overlap during the 4 to 12 months it takes to build.
What is a progress payment?
A progress payment is a staged release of funds from the bank to your builder. Instead of handing over the entire loan amount upfront, the bank pays the builder in installments (usually 5 to 6 stages) as specific milestones are reached, such as laying the foundation, standing the framing, and reaching the lock-up stage.
How much should an initial builder's deposit be?
In New Zealand, an initial builder's deposit should typically be negotiated to between $10,000 and $20,000. While some builders may request 10% of the total build cost upfront, keeping the initial deposit lower reduces your financial risk and makes it significantly easier to manage the bank's lending criteria.
Do I need to pay for variations out of pocket?
Yes, variations must usually be paid for out of pocket. A bank approves a construction loan based strictly on the original Fixed-Price Building Contract. If you choose to upgrade materials mid-build, or if Provisional Sums (PC Sums) like earthworks end up costing more than estimated, the bank will not automatically increase your loan. You must cover these extra costs with your own cash.
Ready to structure your construction finance?
Building a home is highly rewarding, but one wrong move with your progress payments or fixed-price contract can cause massive cash flow stress. We specialize in structuring new build finance so you can focus on the design, not the debt.