Construction loans are specialist home finance products designed to fund the building of a new home or a major renovation, releasing funds in stages as construction progresses rather than as a single lump sum. Understanding how they work, what triggers each payment, and how interest is calculated during the build can save borrowers thousands of dollars and prevent costly delays on site.

Whether you are an owner-builder, buying a house-and-land package, or undertaking a significant knock-down-rebuild, the mechanics of a construction loan differ meaningfully from a standard home loan. This guide walks through every key stage, from the initial approval right through to converting the facility into a standard mortgage once the certificate of occupancy is issued.

What Are Progress Payments and How Do They Work in a Construction Loan?

The defining feature of a construction loan is the progress payment structure, sometimes called a drawdown schedule. Instead of receiving the full approved loan amount on settlement day, you draw funds in instalments that align with specific milestones reached on site. Most lenders use a standard five-stage schedule, though some break it into six or seven stages for larger or more complex builds.

Typical five-stage drawdown schedule

• Stage 1 — Base / Slab: Covers site preparation, footings and the concrete slab. Typically around 10–15% of the total loan.
• Stage 2 — Frame: Covers the structural timber or steel frame, and usually represents 15–20% of the loan.
• Stage 3 — Lock-up: Walls, roof, windows and external doors are in place. Roughly 20–25% of the loan is released here.
• Stage 4 — Fixing / Fit-out: Internal plasterwork, plumbing rough-in, electrical, cabinetry and internal doors. Often the largest single drawdown at 25–30%.
• Stage 5 — Practical completion: Final inspection passed, certificate of occupancy issued, and the remaining balance (typically 10–15%) is released.

Before each drawdown is released, the lender will typically require an inspection by a valuer or quantity surveyor to confirm that work has been completed to the claimed stage. This protects both the borrower and the lender from overpaying a builder for incomplete work. According to Herron Todd White’s March 2026 national review, construction cost inflation has moderated compared with the 2022 peak, but material and labour costs remain elevated in most capital cities, making accurate stage valuations more important than ever.

For a deeper look at how drawdown structures differ between residential and commercial projects, Construction Loans for Development: Financing Your Project from Start to Completion covers the additional complexity involved when scale increases.

How Does the Interest-Only Phase Work During the Build?

One of the most misunderstood aspects of construction finance is how interest is charged during the build period. Unlike a standard loan where interest accrues on the full approved amount from day one, a construction loan charges interest only on the funds that have actually been drawn down at any given point in time. This can produce significant savings over a six-to-twelve month build.

For example, if your total loan is $700,000 but only $105,000 has been drawn after Stage 1, you pay interest on $105,000, not on $700,000. As each stage is completed and a further drawdown is made, the interest-bearing balance increases incrementally. Most lenders require interest-only repayments during the entire construction period, with the loan converting to principal-and-interest repayments once practical completion is reached and the final drawdown has been made.

What interest rate applies during construction?

Rates on construction loans are typically variable during the build phase. As of mid-2026, the Reserve Bank of Australia’s cash rate sits at a level that has seen variable home loan rates ease from their 2023 highs, but construction loan rates still carry a small premium over standard variable rates to reflect the additional administration involved in managing a drawdown facility. Once the build is complete, many borrowers refinance onto a standard variable or fixed product. If you are weighing up how to structure the post-construction facility, the guide to Split Loans Explained: Fixed and Variable Rate Strategy is worth reading before you make that decision.

What Valuations Are Required, and Why Do They Matter So Much?

Valuations sit at the heart of the construction loan process. Lenders require at minimum two formal valuations: an as-if-complete valuation before loan approval, and individual stage inspections throughout the build. The as-if-complete valuation is the figure the lender uses to calculate your loan-to-value ratio (LVR) and determine how much they will lend.

If the as-if-complete valuation comes in lower than the total of your land purchase price plus your fixed-price building contract, you may face a funding shortfall that requires additional cash or a reduction in the scope of works. Herron Todd White’s March 2026 review noted that in Sydney, median house values in growth corridors like North-West Sydney have been supported by strong infrastructure investment, including the Western Sydney Airport, Sydney Metro West and the Western Harbour Tunnel, which helps maintain robust as-if-complete valuations in those precincts. In contrast, fringe markets with less infrastructure backing can see a wider gap between construction cost and completed value.

Key valuation risks to watch for

• Cost overruns: If your builder quotes variations after contract signing, the lender’s approved loan amount may not cover the additional cost.
• Market movement: A twelve-month build in a softening market could mean the final valuation is lower than the as-if-complete figure used at approval.
• Specification changes: Upgrading fixtures or finishes mid-build can push total costs beyond the lender’s approved loan limit.
• Builder insolvency: If your builder enters administration during the build, lenders will re-value the partially completed dwelling, often at a significant discount to the full contract price.

For a comprehensive overview of the valuation process and how it interacts with LVR requirements, Construction Loans Australia: How They Work and What to Watch Out For covers these risks in detail alongside practical mitigation strategies.

Who Is Eligible for a Construction Loan in 2026?

Eligibility criteria for construction loans are broadly similar to those for standard home loans, but lenders apply additional scrutiny given the complexity and risk involved. Key requirements typically include:

• A fixed-price building contract from a licensed builder. Most lenders will not approve a construction loan against a cost-plus contract because the final loan amount cannot be determined in advance.
• Council-approved plans and permits for the proposed works.
• Evidence of builder’s insurance, including home warranty insurance where required by state legislation.
• A minimum deposit, typically 5–20% of the total project cost (land plus construction), depending on the lender and whether Lenders Mortgage Insurance is acceptable.
• Demonstrated serviceability of the fully drawn loan amount, even though you will only be paying interest on drawn funds during the build.

First homebuyers should note that in New South Wales, the First Home Buyer Assistance Scheme threshold was raised to $1.5 million in Sydney in the fourth quarter of 2025, according to Herron Todd White’s March 2026 review. This change meaningfully widens the pool of new builds that can attract stamp duty concessions, particularly in middle-ring and outer suburbs where house-and-land packages regularly exceed the previous threshold.

Investor activity in New South Wales has also risen sharply. Herron Todd White’s March 2026 data shows investor lending grew from below 30% of new NSW lending in mid-2020 to 46.2% by September 2025, the highest proportion in nearly a decade. New loans to investors rose 12.3% over the twelve months to September 2025, compared with just 1.7% for owner-occupiers. This surge in investor demand has increased competition for construction finance, making pre-approval and a well-prepared application more important than ever.

How Does a Construction Loan Convert to a Standard Home Loan?

Once practical completion is reached and the final progress payment has been made, the construction facility automatically converts to a standard principal-and-interest home loan in most cases. At this point, interest accrues on the full outstanding balance and full repayments begin.

This is also an appropriate moment to review your broader mortgage strategy. Some borrowers use equity built up during construction to access home equity for landscaping, fit-out or a subsequent investment purchase. Others refinance to a more competitive long-term product. Considering the right loan term at this stage is also critical: the Home Loan Guide Australia 2026 provides a useful framework for comparing loan types and rate structures once construction is finalised.

Checklist before your construction loan converts

1. Obtain the certificate of occupancy or certificate of practical completion from your builder.
2. Confirm the final drawdown amount with your lender and ensure the builder’s final invoice matches the contract.
3. Update your home and contents insurance to reflect the completed dwelling value.
4. Notify your lender of the completion date so repayments can be recalculated accurately.
5. Review whether refinancing to a lower-rate product at this stage makes financial sense.

What Are the Biggest Mistakes Borrowers Make with Construction Loans?

Having guided many clients through the construction finance process, several common mistakes arise repeatedly. Being aware of them in advance can prevent significant financial and emotional stress.

• Underestimating contingency funds: Most experienced advisers recommend holding a cash contingency of at least 10% of the total construction contract value for variations, site surprises and cost overruns that are not covered by the loan.
• Signing a non-fixed-price contract: Cost-plus arrangements leave you exposed to unlimited cost increases and will disqualify you from most construction loan products.
• Not verifying the builder’s licence and insurance: Builder insolvency during a build is one of the most financially damaging outcomes a borrower can face. Always verify currency of licence, home warranty insurance and public liability cover before signing.
• Overlooking land loan timing: If you purchase a block before construction begins, you will likely need a separate land loan that bridges into the construction loan. The interest costs during this period can add up quickly if construction is delayed.
• Assuming drawdowns are automatic: Drawdowns require documentation and a valuer inspection. Allow at least five to ten business days for each drawdown to be processed, and factor this into your payment schedule with the builder.

Construction loans are powerful financing tools when used correctly, but they reward preparation, documentation and proactive communication with both your lender and your builder. Understanding the mechanics of progress payments, managing the interest-only build phase and commissioning accurate valuations at every stage are the three pillars of a successful construction loan experience. If you are ready to explore your options in more detail, speaking with a qualified mortgage broker who specialises in construction finance is the most effective first step.