Unlock the secrets to funding your extension project

Construction loans aren't just for building from scratch.

If you're buying a property with plans to extend it immediately, you need finance that covers both the purchase and the build. A standard home loan won't cut it because you're not buying a finished product. You're buying a base with work to do, and the funding needs to match that timeline.

The structure that works is a construction-to-permanent loan that rolls the purchase price and extension costs into one facility. You draw down the purchase amount at settlement, then access the construction portion in stages as the extension progresses. The lender only charges interest on what's been drawn, which keeps your repayments lower during the build.

How the Purchase and Extension Structure Works

You'll need a loan that covers the property purchase price plus the full cost of the extension. The lender assesses your application based on the end value of the property after the extension is complete, not just what you're paying upfront. That means you'll need council-approved plans, a fixed-price building contract with a registered builder, and a detailed cost breakdown before the lender will approve the full amount.

At settlement, you draw down the funds to buy the property. The extension portion sits in reserve and gets released according to a progressive drawdown schedule tied to construction milestones. Lenders typically release funds in five or six stages: base stage, frame stage, lock-up, fixing, practical completion, and final inspection. Each stage requires a progress inspection by the lender's valuer before the next payment is released.

Consider a builder who purchases a three-bedroom house in a growth corridor, planning a two-storey extension to add a fourth bedroom, ensuite, and expanded living area. The contract price for the extension is fixed at the time of purchase. The lender approves the loan based on the projected value of the extended property, not the purchase price alone. The builder draws down the purchase funds at settlement, then accesses the construction funds progressively as each stage is signed off.

What Lenders Look for in a Purchase and Extension Application

Lenders want certainty that the extension will be completed and that the finished property will be worth more than the total loan amount. That means you need council approval locked in before you apply, not just a development application in progress. If the plans are still subject to conditions or awaiting final sign-off, most lenders won't proceed.

You'll also need a fixed-price contract with a registered builder. Cost-plus contracts or owner-builder arrangements are harder to finance on a purchase and extension deal because the lender can't assess the final loan-to-value ratio with confidence. If you're doing the extension work yourself, owner builder finance is available through specialist lenders, but the approval process is stricter and you'll need to demonstrate your qualifications and experience.

The lender will order a valuation that includes both the current property value and the estimated value after the extension is complete. If the valuation comes in lower than expected, the loan amount may be reduced or you'll need to increase your deposit to cover the gap.

Interest Charges and Repayment Options During the Build

During construction, you're only charged interest on the amount that's been drawn down. If you've drawn $400,000 for the purchase and $80,000 for the first two construction stages, you're paying interest on $480,000, not the full loan amount. That keeps your repayments manageable while the extension is underway.

Most lenders offer interest-only repayment options during the construction phase, which means you're only covering the interest charges each month without paying down the principal. Once the extension is complete and the loan converts to a standard home loan, you switch to principal and interest repayments based on the full loan amount.

Some lenders charge a progressive drawing fee each time funds are released, typically between $150 and $400 per drawdown. That's on top of the standard interest charges, so factor those fees into your budget when you're working out the total cost of the extension.

Timeline Requirements and Settlement Considerations

Most construction loans require you to commence building within a set period from the loan approval, usually 90 to 180 days. If you're buying a property with the intention to extend, that timeline starts from settlement, not from the date the loan is approved. You'll need your council plans finalised, your builder locked in, and your contract signed before you settle on the purchase.

If there's a delay between settlement and the start of construction, you're paying interest on the purchase amount without the extension work progressing. That's why the timing needs to be tight. Line up your builder, get your plans approved, and make sure the contract is ready to sign as soon as you've settled on the property.

In scenarios where the existing dwelling requires demolition or significant remediation before the extension can start, the lender will want a clear timeline for that work and confirmation that it's included in the building contract. If the demolition is being handled separately, you'll need to fund that work upfront or include it as a separate line item in the construction budget.

How the Loan Converts After Practical Completion

Once the extension reaches practical completion and the final inspection is signed off, the loan converts from a construction facility to a standard home loan. At that point, your interest-only period ends and you begin making principal and interest repayments based on the full loan amount.

The conversion happens automatically, but you'll need to provide the lender with proof of practical completion, usually in the form of a certificate from the builder and a final valuation confirming the property is worth at least the total loan amount. If the final valuation comes in below the loan amount, some lenders may require you to pay down the difference or adjust the loan terms.

You'll also need to arrange insurance for the completed property at this stage. During construction, the builder's insurance typically covers the works, but once the extension is finished, you're responsible for insuring the full property as an owner-occupier or investor.

If you're planning an extension on a property you're about to purchase, the structure needs to be right from the start. Call one of our team or book an appointment at a time that works for you.

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