Why Knockdown Rebuild Finance Needs Early Planning

A knockdown rebuild involves demolishing an existing dwelling and constructing a new home on the same block.

The funding structure differs substantially from a standard purchase loan because lenders release funds progressively as construction reaches specific milestones, not as a single upfront amount. You need approval for both the land component and the construction component, each assessed separately, and the timeline from settlement to completion typically spans eight to twelve months depending on builder schedules and council approval processes.

How Construction Loan Drawdowns Actually Work

Lenders release funds in stages that align with your progress payment schedule, not when you need the money for materials or labour.

Your builder submits a claim at each stage, the lender arranges an independent inspection to confirm that stage is complete, and once verified, the lender releases that portion of the loan amount directly to the builder. In Adelaide, most registered builders work to a five or six stage schedule covering base, frame, lock-up, fixing, and completion. You only pay interest on the amount drawn down at each stage, which means your repayments increase as construction progresses. Between drawdowns, you might be on interest-only repayment options while the build advances, then convert to principal and interest once construction completes and the loan transitions to a standard home loan.

Consider a buyer demolishing a cottage in Prospect to build a two-storey custom design. The land component settles at the existing property value, then the construction loan activates. At base stage, the lender releases around 15% of the build cost after inspection confirms slab and footings are complete. At frame stage, another 25% releases once the timber or steel frame is erected and roof trusses are in place. Lock-up stage triggers the next drawdown when external walls, windows, and roofing are weatherproof. The buyer pays interest only on the cumulative amount released, so after three stages representing roughly 60% of the build cost, repayments cover interest on that portion while the remainder sits undrawn. Once the final inspection clears and the builder hands over keys, the full loan amount is drawn and the loan converts to a standard variable or fixed rate product.

What Lenders Assess Before Approving Knockdown Rebuild Finance

Lenders evaluate your income and existing debts as they would for any loan, but they also assess the building contract, the builder's credentials, and whether the finished property will provide sufficient security.

You need a fixed price building contract with a registered builder before formal approval, along with council approval or at least evidence that a development application has been lodged. Lenders want to see detailed plans, a clear cost breakdown, and confirmation that you can commence building within a set period from the disclosure date, usually six months. The valuation process involves two assessments: one for the land in its current state, and one for the completed dwelling based on the approved plans. If the finished home's projected value does not cover the total loan amount, you may need a larger deposit or additional equity to bridge the gap.

In our experience working with buyers in Adelaide's inner suburbs, the valuation on completion can sometimes fall short of construction costs if the custom design includes features that do not add proportional market value. A buyer planning a knockdown rebuild in Norwood wanted extensive internal steelwork and imported fixtures that pushed the build cost well above comparable sales in the area. The lender's valuer assessed the completed home at a figure that left a shortfall, so the buyer either needed to increase their deposit or scale back the inclusions to align the build cost with the property's expected market value. This assessment happens during the application stage, not after construction starts, so engaging a broker early allows time to adjust plans or explore lenders with different valuation policies.

Why the Progress Payment Schedule Determines Your Cash Flow

Your repayments increase each time the lender releases a drawdown, so understanding the progress payment schedule before you commit helps you plan for rising costs during construction.

Most builders require a deposit of 5% to 10% of the build cost on contract signing, then claim the first progress payment once the base is complete. If your builder uses a cost plus contract instead of a fixed price building contract, the progress payment finance structure becomes more complex because the final cost is not locked in, and most mainstream lenders will not approve funding on a cost plus basis. Adelaide council approval timelines can also affect when construction actually starts, which means you might be carrying the land loan component for several months before the first drawdown occurs.

A typical five-stage schedule for a knockdown rebuild in Unley might involve a 10% deposit on signing, then 15% at base, 25% at frame, 25% at lock-up, 20% at fixing, and 5% at completion. Each drawdown triggers a progress inspection, usually costing a few hundred dollars as a Progressive Drawing Fee, and once the inspection report confirms the stage is complete, the lender transfers funds to the builder within a few business days. Between base and frame, you might wait four to six weeks, during which your repayments cover interest on the base drawdown only. Once frame completes and the next 25% releases, your interest cost increases accordingly. Planning for these incremental increases is particularly important if you are also paying rent elsewhere or managing ongoing costs on the existing land.

How the Loan Transitions After Construction Completes

Once the final inspection clears and the builder issues a certificate of completion, the construction loan converts to a standard home loan and your repayments adjust to principal and interest.

During construction, you are typically on interest-only repayment options, which means you are not reducing the principal balance, just covering the cost of borrowed funds as each stage draws down. After completion, the loan reverts to a construction to permanent loan structure, and you start repaying both principal and interest over the agreed term, usually 25 to 30 years. The interest rate during construction might differ from the ongoing rate, so confirming the post-construction rate and any rate lock options during the application stage prevents surprises once the build finishes.

Some lenders allow you to lock in a fixed rate for the construction phase, then convert to a different rate type once the loan transitions. Others offer a split structure where part of the loan is fixed and part remains variable, giving you some protection against rate movements without losing all flexibility. If you are building in an area like Glenelg or Brighton where property values have been rising, the completed valuation might come in higher than the initial assessment, which can improve your loan-to-value ratio and potentially open up better rate options or allow you to drop lender's mortgage insurance if you were initially above 80% LVR.

Why Early Approval Matters for Knockdown Rebuild Projects

Getting conditional approval before you finalise your building contract gives you certainty on borrowing capacity and highlights any issues with the builder, the plans, or the projected valuation.

Waiting until after you sign the contract to apply for construction finance can leave you locked into a build you cannot fund, or force you to renegotiate with the builder if the lender requires changes. Engaging a mortgage broker who understands construction loan applications means you can submit a complete application with all supporting documents, including council plans, builder registrations, and a detailed cost breakdown, which speeds up the approval process and reduces the risk of conditions you cannot meet.

In Adelaide, some buyers assume they can secure construction funding as easily as a standard purchase loan, but lenders require substantially more documentation and the assessment process takes longer. A buyer looking at a knockdown rebuild in Burnside approached us after signing a building contract, only to discover the lender would not approve the project because the builder was not on their approved panel and the contract included provisional sums that made the final cost uncertain. The buyer had to negotiate a new contract with a different builder, delaying the project by several months and incurring additional costs for revised plans and a new development application. Starting the finance conversation before signing anything allows you to choose a builder and contract structure that aligns with lender requirements, not the other way around.

How Owner Builder Projects Change the Approval Process

If you plan to manage the build yourself as an owner builder, your finance options narrow substantially because most mainstream lenders will not provide owner builder finance.

Lenders see owner builder projects as higher risk because there is no licensed builder to hold accountable if the project stalls or the quality falls short of the approved plans. The few lenders who will consider owner builder finance typically require a larger deposit, charge a higher interest rate, and impose stricter conditions around progress inspections and drawdown approvals. You also need to demonstrate relevant experience or qualifications, provide detailed contracts with sub-contractors including plumbers and electricians, and arrange separate insurance that covers construction risks normally carried by a registered builder.

For most buyers in Adelaide pursuing a knockdown rebuild, working with a registered builder on a fixed price building contract delivers better finance terms, lower rates, and a smoother approval process than attempting an owner builder approach. The perceived savings from managing the build yourself often disappear once you factor in the higher borrowing costs, the time required to coordinate trades, and the risk of cost overruns if the project takes longer than expected.

If you are considering a knockdown rebuild in Adelaide and want to understand how construction loan structures apply to your situation, call one of our team or book an appointment at a time that works for you.

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