Key Takeaways
- The day demolition finishes, your loan security becomes vacant land, so lenders value the deal as land value plus your fixed-price build contract on an on-completion basis.
- Any mortgage on the existing home is usually restructured into the new construction facility before the lender will consent to demolition.
- Demolition costs typically sit outside the build contract, and lenders differ on whether they fund them or expect you to pay from savings or equity.
- You will often pay rent and loan interest together during the build, and lenders test both when they assess serviceability.
Across much of Sydney, the land under an older house is now worth far more than the house standing on it. That is why so many owners weigh up a knock-down rebuild (KDR). They keep the block in the street they already like and replace a tired dwelling with a home built for how they actually live.
Knock-down rebuild finance does not behave like a renovation loan or a standard construction loan on a vacant block. You start with a mortgaged house, deliberately destroy the thing the bank holds as security, then ask a lender to fund a build on what is now bare land.
Working out how a construction loan broker structures the deal before you sign a demolition contract can save an expensive mid-project surprise, because the numbers have to hold at every stage.
Why Demolition Changes How Lenders See Your Property
Once the bulldozer finishes, your property is vacant land, and that single moment drives everything about knock-down rebuild finance. A lender’s security is whatever it could sell if the loan went wrong, so from that day the old house counts for nothing.
Lenders do not assess a KDR against what your home is worth today. The valuer instead gives an on-completion valuation, which is what the property should be worth once the new home is finished, based on the land value plus the fixed-price building contract. The lender applies its maximum Loan to Value Ratio (LVR), the loan as a percentage of the property value, to that figure, typically using the lower of the valuation or the land-plus-contract cost.
This is also why the equity you think you have can shrink. If your home is worth $1.6 million standing but the land alone is worth $1.2 million, roughly $400,000 of value comes down with the house. Lenders manage that dip by approving the whole package, the old loan payout and the build, before demolition starts, so the figures work at every stage.
Sequencing a Knock-Down Rebuild Loan
A knock-down rebuild is one finance transaction with several moving parts, and the order they happen in decides whether it holds together. Demolishing before the new loan is approved is where projects come unstuck, because few lenders will touch a half-finished deal. The stages run in this order:
Clearing the Existing Mortgage
A current loan on the home needs your lender’s consent before demolition. In practice, the existing mortgage is refinanced or restructured into the new construction facility, one loan that pays out the old debt and funds the build. Some borrowers also draw on equity at this point to cover soft costs like design, engineering and approvals, which an equity loan broker can arrange as part of the whole package.
Valuing Land and Contract
The lender orders a valuation based on your land, the signed fixed-price building contract and the approved plans, and the valuer estimates the on-completion value. Where that figure supports the total lending at the lender’s maximum LVR, often around 80% before Lenders Mortgage Insurance (LMI) is added to protect the lender on higher-LVR loans, the deal proceeds. Some lenders go higher with LMI, though construction policies vary.
Funding Demolition and Early Costs
Demolition usually sits outside the building contract and is handled by a separate contractor, which is one of the awkward gaps in a KDR budget. Some lenders release funds for it as an early advance once the full package is approved, while others expect you to cover it from savings or pre-arranged equity. The same applies to costs that land before the first progress payment, such as service disconnections and asbestos removal on older Sydney homes.
Drawing Progress Payments
Once construction starts, the loan is drawn in progress payments, staged advances released as the builder finishes each stage from slab through to completion. You pay interest only on what has been drawn, so repayments start small and grow as the build advances. The lender usually requires evidence at each stage before releasing funds, which stops anyone paying ahead of the work.
Numbers Behind a Sydney Knock-Down Rebuild
These figures are illustrative, but they show how the maths moves. Say your home is worth around $1.6 million with a $500,000 mortgage, which looks like $1.1 million of equity. The valuer puts the land alone at $1.2 million, so once the house comes down, your equity against the security is $700,000.
You sign a fixed-price building contract for $900,000. The lender assesses the on-completion position as land plus contract, $2.1 million. Your total funding need is the $500,000 payout, the $900,000 build and roughly $60,000 for demolition and pre-construction costs, about $1.46 million. Against $2.1 million, that is an LVR of around 70%, comfortably inside most lenders’ standard limits.
Two things made this work. The old mortgage was modest against the land value, and the contract price was fixed. Had the existing loan been $900,000, total funding would push toward $1.86 million and an LVR near 89%, the territory where LMI or a budget rethink enters the conversation. Your current mortgage measured against your land value is the first number worth checking on any KDR.
Rent and Interest While You Build
Most families cannot live on a demolition site, so a knock-down rebuild usually means renting for the 12 months or more the project runs. You then pay rent and interest on the drawn portion of the loan at the same time, and lenders count both when they test serviceability.
Banks assess your capacity against a serviceability buffer set by the Australian Prudential Regulation Authority (APRA) at 3 percentage points above the actual rate, and they weigh your rent alongside it. Some non-bank lenders apply their own buffer instead. A household that services the loan comfortably once it is living in the finished home can therefore look tighter on paper while also paying Sydney rent.
Most construction facilities allow interest-only repayments during the build, which eases the squeeze. A cash buffer for the overlap, and for the near-inevitable variations and delays, strengthens any application.
Why a Fixed-Price Contract With a Licensed Builder Is Near-Mandatory
Lenders fund KDR projects almost entirely under a fixed-price building contract with a licensed builder who carries the required home building compensation cover. The logic is simple. The lender commits today to a valuation that depends on the home being finished for a known cost.
A cost-plus contract or an owner-builder arrangement removes that certainty, and most lenders decline those structures or cut the maximum LVR sharply. A fixed-price contract does not remove every risk, since provisional sums for site works and excavation can still move, but it caps the core build cost, gives the valuer a solid basis for the on-completion figure and underpins the progress payment schedule. A builder who resists a fixed-price contract is a finance problem as much as a construction one.
Knock-Down Rebuild vs Selling and Buying in Sydney
The alternative to a KDR is selling and buying something newer elsewhere, and in Sydney that path carries heavy transaction costs. You pay agent fees on the sale, then transfer duty, commonly called stamp duty, on the purchase, which can run to a six-figure sum on a family home. A knock-down rebuild avoids that purchase duty, because you are not buying another property.
Set against that saving, a KDR brings rent during the build, demolition costs and construction risk, and it only makes sense if you want to stay where you are. Lender appetite also differs. Some are practised and comfortable with KDR lending, while others apply tighter LVR and policy settings, which is where a Sydney mortgage broker earns their keep. DIY Lending compares construction policies across more than 40 lenders to match the project to a lender that handles KDR deals well.
Finance Settled Before the House Comes Down
A knock-down rebuild stops being daunting once the funding is locked in the right order. The existing loan is restructured, the fixed-price contract is signed, the on-completion valuation supports the LVR, and the demolition and rent-plus-interest costs are planned for before anything is knocked over. Handled that way, the bulldozer arrives after the finance is settled, not before.
The projects that strike trouble are almost always the ones where demolition ran ahead of the money. If you are weighing up a knock-down rebuild on your Sydney block, the team at DIY Lending can talk you through the structure and the lenders that suit it.
Frequently Asked Questions (FAQs)
1. Can I demolish my house while it still has a mortgage?
Not without your lender’s consent. The house is the lender’s security, so pulling it down without approval breaches your mortgage terms. In practice, the existing loan is refinanced or restructured into the new construction facility first, so the lender has approved the whole project, the payout, the demolition and the build, before any work starts.
2. How do lenders value a knock-down rebuild?
They use an on-completion valuation. The valuer assesses what the finished home should be worth from the land value plus your fixed-price building contract and approved plans, and the lender applies its maximum LVR to that figure, typically using the lower of the valuation or the land-plus-contract cost.
3. Who pays for the demolition?
Demolition usually sits outside the building contract, so it is quoted and contracted separately. Some lenders release funds for it as an early advance under the approved facility, while others expect you to pay from savings or pre-arranged equity. Confirming your lender’s position before you sign the demolition contract avoids a cash-flow gap.
4. Do I pay rent and loan repayments at the same time?
Usually, yes. Most owners rent during the build while paying interest on the drawn portion of the construction loan, and lenders assess both commitments when they test serviceability. Interest-only repayments during construction are standard on most facilities and help ease the overlap.
5. Can I do a knock-down rebuild as an owner-builder?
It is difficult to finance. Most lenders want a fixed-price contract with a licensed builder carrying home building compensation cover, because that fixes the cost their valuation relies on. Owner-builder loans exist with a small number of lenders, though typically at much lower LVRs and with stricter conditions.
This article is general information only. It does not take your objectives, financial situation or needs into account, and you may wish to speak with a qualified professional before acting.