Construction Loans

Knockdown rebuild finance in NSW: what lenders need before they approve

Published 24 July 2026 · Updated 24 July 2026 · 6 min read · By Shane Heness, mortgage broker

A knockdown rebuild is financed as a construction loan secured against the land. The lender values the property on an as-if-complete basis, using the stamped plans and a fixed price building contract, while the old house is still standing. Approval needs council or private certifier approval, a fixed price contract, home warranty insurance and a full specification. In NSW, a complying development certificate is usually the faster approval path where the design fits the standard controls.

Knockdown rebuilds are more common in Western Sydney than anywhere else in the state, because the land is worth keeping and the houses on it often are not. The finance is straightforward once you understand what the lender is actually valuing.

How the valuation works

This is the part that confuses people. You are asking a lender to lend against a house that does not exist yet, on land currently occupied by a house you are about to destroy.

The valuer is instructed on an as-if-complete basis. They take the stamped plans, the specification and the fixed price contract, and they assess what the finished property will be worth on that land at completion. The existing dwelling is essentially ignored, other than as a cost to remove.

Knockdown rebuild funding, worked example
Item	Amount	Notes
Land value (existing property)	$850,000	Current value with the old dwelling
Existing mortgage	$300,000	Refinanced into the construction facility
Demolition	$35,000	Often funded outside the construction contract
Fixed price build contract	$720,000	Drawn in stages
As-if-complete valuation	$1,650,000	Land plus completed dwelling
Total borrowing required	$1,055,000	Existing debt plus demolition plus build
Resulting LVR on completion	64%	Comfortably inside standard policy

Illustrative only. Your own land value, contract price and valuation will differ. This is not a quote or an indication of approval.

Note what makes this work: the as-if-complete valuation is well above the total borrowing, so the LVR at completion is modest even though the borrower is funding almost the whole build. That is the normal shape of a well-planned rebuild, and it is why lenders are comfortable with them.

CDC or DA: the approval path

NSW gives you two routes to approval, and the choice affects your timeline more than your finance.

Approval pathways for a NSW knockdown rebuild
	Complying development certificate (CDC)	Development application (DA)
Issued by	A private certifier or council	Council
Typical timeframe	2 to 6 weeks	3 to 9 months, sometimes longer
Requires	Design fits within the standard codes: setbacks, height, floor space ratio, landscaping, lot size	Anything outside the codes, or a lot with constraints
Neighbour notification	Notification only, no objection process	Public exhibition and objections
Lender treatment	Accepted as approval	Accepted as approval
Common blockers	Heritage, flood, bushfire, acid sulfate soils, foreshore, narrow or battleaxe lots	Fewer hard blockers, but slower

Most standard rebuilds in Blacktown, Penrith, Parramatta and the Hills go the CDC route where the block allows it. Where the block is flood affected, heritage listed or unusually shaped, a DA is the only option and the timeline stretches accordingly. That timeline matters for finance because approvals expire, and so do loan approvals.

What lenders want to see

Approval documents. The stamped CDC or DA plans, matching the contract.
A fixed price building contract. Cost plus contracts are hard to finance and some lenders will not consider them at all.
Home warranty insurance for the contract value, in your name, issued before the first drawdown.
The full specification and inclusions schedule. The valuer values the specification, so vagueness costs you.
Builder licence details and evidence the builder is currently licensed for the work.
BASIX certificate for the new dwelling.
Demolition arrangements, including how demolition is being paid for and whether an asbestos report has been done.
Evidence of where you will live during the build, because the lender will assess rent alongside your loan repayments.

Demolition: the gap most people miss

Demolition sits awkwardly between the old loan and the new one. In Sydney, a standard single storey demolition runs roughly $25,000 to $45,000, and asbestos removal pushes it higher. Houses built before the late 1980s frequently have asbestos in the eaves, the bathroom sheeting or the fence.

Where demolition is inside the builder's fixed price contract, it is funded as part of the first drawdown and everything is simple. Where it is a separate contract, which is common, many lenders will not fund it from the construction facility. That means either cash, or an equity release against the existing property completed before the build facility starts.

Getting this sequenced right is worth doing early, because a demolition that has already happened changes the security position and can complicate the valuation.

The timeline to plan against

1Months 1 to 3
Design and approval
Draftsperson or architect, then CDC through a private certifier, or a DA lodged with council. This is the stage most likely to blow out.
2Months 2 to 4
Builder selection and fixed price contract
Tender the plans, compare inclusions rather than headline prices, and sign a fixed price contract.
3Weeks 1 to 4 of finance
Loan application and as-if-complete valuation
Submission, valuation on the plans and contract, then formal approval.
4Weeks 4 to 6
Settlement of the facility and move out
The existing loan is refinanced into the construction facility, and you move into rental accommodation.
5Weeks 6 to 10
Demolition and site preparation
Service disconnections, asbestos clearance where required, demolition, site clear.
6Months 4 to 14
Construction in progressive drawdowns
Slab, frame, lock-up, fit-out, completion. Repayments climb as each stage is drawn.
7Month 14 to 18
Practical completion and handover
Final inspection, final drawdown, occupation certificate, and the loan converts to principal and interest.

Twelve to eighteen months from first drawing to handover is realistic for a standard rebuild. The finance is usually the shortest part of it.

The cost people forget

You are paying rent and loan interest at the same time for the whole build. On the worked example above, interest through the build averages around $4,000 a month, and Western Sydney rent for a family home is $650 to $850 a week. That combined cost across fourteen months is a real number and it belongs in the budget from day one, not month six.

The site costs that blow rebuild budgets

The build contract is the number everyone focuses on. The site costs are the number that moves. On an established block, the ground under the old house has been there for sixty years and nobody has looked at it.

Common site cost surprises on Western Sydney rebuilds
Item	Indicative cost	When you find out
Asbestos removal	$5,000 to $25,000	Pre-demolition survey
Reactive clay soil, deeper footings	$10,000 to $40,000	Soil test, before contract if you order it early
Retaining walls on a sloping block	$15,000 to $60,000	Detailed survey and design
Sydney Water sewer main under the block	$8,000 to $50,000	Sewer diagram, obtain it before you buy or design
Service disconnections and reconnections	$3,000 to $12,000	Demolition stage
Tree removal and protection orders	$2,000 to $15,000	Council arborist assessment

Indicative Sydney ranges at September 2026. Costs vary by block, council and contractor.

Two documents remove most of this uncertainty and both can be obtained before you commit: a sewer diagram from Sydney Water, and a soil classification report. Together they cost a few hundred dollars and routinely change the design, the build price, or the decision to proceed at all.

From a finance perspective, the risk is that site costs emerge after the loan is approved against the original contract sum. The lender approved $720,000 of building work, the build is now $770,000, and the extra has to come from somewhere. A contingency of five to ten percent held in cash outside the contract is the simplest protection, and it is the thing most rebuild budgets leave out.

We build that figure into the servicing assessment before anything goes to a lender, because a rebuild that services on paper but not in practice is nobody's idea of a good outcome. Our construction loans page covers the drawdown process in detail, or book a free call and we will map your block against a realistic funding plan.

Frequently asked questions

Yes, and that is the standard structure. The land is the security, the existing dwelling is demolished, and the lender funds the build in progressive drawdowns. The valuation is done on an as-if-complete basis using the plans and the fixed price contract, so the valuer values the finished house on that land, not the house standing there today.

Some do and some do not. Where demolition is a separate contract rather than part of the builder's fixed price, many lenders expect it to be paid from your own funds or from an equity release completed before the construction facility starts. Budget $25,000 to $45,000 for a standard single storey demolition in Sydney, more where asbestos is present.

For finance purposes it is usually faster and cleaner. A CDC can be issued by a private certifier in weeks where a development application can take months, and lenders treat a CDC as approval just as they do a DA. The trade-off is that a CDC requires the design to fit within the standard controls, so it does not suit every block.

It continues. You keep paying on the existing loan, or on the drawn balance of the construction facility, and you also need somewhere to live. Budget for rent plus loan interest across the full build period, which for a knockdown rebuild is usually 12 to 18 months from demolition to handover.

Written by Shane Heness

Owner and mortgage broker at LoanBuddy, Parramatta NSW. Eight years as a mortgage broker and a property investor since 2015. Credit Representative #528658 under Australian Credit Licence #389328.