People who ask us whether to knock down or renovate have usually half-decided already. Some love the street but not the house. Others have priced an extension and wondered whether, for that money, they could start again. The knock down rebuild vs renovation question has a right answer for each house, but rarely the same answer twice. The facts that decide it can mostly be checked before you pay for any design, and this guide goes through them in order.
Knock down rebuild vs renovation: what decides it?
Six things settle most cases. The table gives the short version, and the sections below explain each one.
| Factor | Points towards renovating | Points towards knocking down and rebuilding |
|---|---|---|
| Structure and condition | Sound footings, frame and roof, with local problems you can fix | Failing footings, widespread rot, termite or damp damage, a frame and roof that would all need replacing |
| How much of the house works | The front rooms, the street presence or the main living spaces already work | Very little works: poor orientation, low ceilings, a plan you would gut anyway |
| Heritage | A heritage item, or a house that contributes to a heritage conservation area | No heritage listing or conservation area |
| Today's planning controls | The existing house is closer to the boundaries, or bigger, than a new one could be | Current controls allow a better house than the one that's there |
| How much would change | The work is concentrated in one part of the house | The renovation would touch nearly every room |
| Living arrangements | You need to stay nearby or can stage the work | You can move out for the whole build and carry the rent |
Is the structure worth keeping?
Start here, because it can end the conversation. A renovation only saves money if the bones it keeps are sound.
Before you design anything, have the house properly inspected, and bring in a structural engineer if there is cracking, movement, sagging floors, or a plan to add weight such as a second storey. Footings, floor framing and roofs are where old Sydney houses tend to hide trouble. Sydney homeowners have reported small jobs growing several times over once walls and floors were opened up, through water damage, failed piers and rotten framing.
A poor report doesn't automatically mean a rebuild. Restumping, new bearers and a new roof are routine renovation work. It means the renovation budget has to carry them, and that is the figure to compare against a rebuild.
How much of the house already works?
Walk through the house and mark each room: keep as it is, keep and refresh, or change completely. If most rooms land in the last column, and the changes mean moving the stair, lifting the roof or rearranging the kitchen and bathrooms, you are close to paying for a new house inside old walls, without the freedom a new design would give you.
The opposite pattern is just as common in older Sydney houses: front rooms with good proportions, high ceilings and a street presence nobody wants to lose, and a dark, cramped back half. That usually favours keeping the front and replacing or extending the rear.
Is the house in a heritage conservation area?
If it is, the choice may already be made for you.
A full knockdown can't use the faster CDC route there. In a heritage conservation area, complying development only covers limited demolition, such as detached structures and internal walls. Taking down the house itself needs a development application to council.
Councils also set a high bar for that application. Inner West Council's controls, for example, only allow a house that contributes to the area to be demolished where it can't reasonably be kept. To make that case, expect to provide a structural engineer's assessment, a cost comparison from a quantity surveyor, the options for keeping the house and the effect on the streetscape. If the house is itself a listed heritage item, demolition is harder still.
So in a conservation area, the realistic choice is usually between renovation options, not between renovating and rebuilding. Our guide to renovating in an Inner West heritage conservation area covers what you can change.
What could a new house be under today's planning controls?
This is the factor people most often miss. An older house was built under the rules of its day. It may sit right on a side boundary, cover more of the block or have more floor area than a new house would be allowed now. When you renovate, the parts you keep generally stay where they are, even if they sit closer to a boundary than new work would be allowed. When you rebuild, the new house is assessed against current controls: setbacks, height, floor space ratio, landscaped area and, in a conservation area, how it fits the street. On a narrow terrace or semi block, a rebuild can give you less than the house you knocked down.
The reverse happens too. On a larger suburban block, current controls may allow a two-storey house with far more usable space than the original cottage. That is often where a rebuild earns its cost.
Before deciding, find out which controls apply: your council's local environmental plan and development control plan, and whether the land is excluded from complying development, which the Section 10.7 planning certificate tells you. Our guide to CDC or DA explains what to look for.
Knockdown rebuild cost in Sydney: how does it compare with renovating?
Compare the two on the same terms, all in, or the comparison means nothing.
For new houses, the 2026 Riders Digest from quantity surveyors Rider Levett Bucknall puts custom-built single and double storey houses in Sydney at $2,500 to $7,600 per square metre of floor area, or $750,000 to $2.5 million for a 325 m² house, at fourth-quarter 2025 rates excluding GST. Its Sydney rates for demolishing a single or double storey brick house with a tiled roof are $175 to $280 per square metre, so about $35,000 to $56,000 for a 200 m² brick house before anything unusual turns up.
Renovation usually costs more per square metre than new work of the same standard, because of demolition, propping and matching old to new. Sydney homeowners have reported renovation and extension quotes of roughly $4,000 to $6,500 per square metre. But a renovation only builds the parts you change.
| Cost | Renovating | Knocking down and rebuilding |
|---|---|---|
| Building work | Only the parts you change, at a higher rate per m² | The whole house, at new-build rates |
| Demolition | Partial | The whole house. About $175 to $280 per m² for a brick house in Sydney, excluding GST |
| Asbestos | Possible in older houses, in the parts you remove | If the house was built before 1987, it must be handled and removed by a licensed contractor |
| Services, landscaping, driveway | Usually only where the work touches them | Usually all new |
| Rent and storage | Sometimes avoidable by staging the work | Almost always, for the whole build |
| Contingency | Higher, for what the old house is hiding | Lower for the new structure, but site surprises still happen |
| Fees and levies | Scale with the cost of the work. The long service levy, for example, is 0.25% of building work worth $250,000 or more | The same rules, on a larger cost |
Sydney homeowners who have rebuilt have reported that the advertised build price was only the start, once demolition, site costs, landscaping and variations were added.
Our view on whether to renovate or rebuild: if the renovation would touch nearly every room, a rebuild is often closer in cost than people expect once rent and site costs are counted honestly. If the work is concentrated at the back of the house, renovating usually wins. Either way, the answer comes from pricing both.
What about capital gains tax on your home?
This is the point to talk to a tax adviser. It helps to know the question exists before you decide.
The ATO lets you, in some cases, treat the land as your main residence for up to four years while you build a new home on it, including one that replaces a demolished house. The conditions include moving in as soon as practicable after it is finished and living there as your main residence for at least three months.
How those rules apply depends on what else you own and where you live during the build. Read the ATO's page on building or renovating your home and speak to a registered tax agent before you sign a building contract.
What approvals does a knockdown-rebuild need, and how long do they take?
Two things need approval: taking the old house down and building the new one. They are often dealt with together.
- A complying development certificate (CDC) is possible where the land isn't excluded and the design meets the codes. Both the demolition and the new house can be approved by your council or a registered certifier as complying development. Approval can take as little as 20 days, plus neighbour notification where required. You also need to notify your neighbours before demolition begins.
- A development application (DA) is needed where a CDC isn't available, for example most demolitions in a heritage conservation area, or where the design doesn't meet the code. In September 2026, Inner West Council averaged 96 days to assess a DA, the City of Sydney 53 and Lane Cove 68. Once the DA is approved, you still need a construction certificate before work can start.
Add the time for design and reports before lodging, and the builder's construction program after. Our page on DA and CDC approvals explains how we manage both routes.
Where will you live while it's built?
A knockdown-rebuild means moving out from before demolition until the new house is finished, so budget for rent, storage and two moves across the whole period. Ask your builder for a realistic construction program and add a buffer, because rent is due every month whether the job is on time or not. Some Sydney homeowners have reported budgeting a year or more of rent for a rebuild.
A renovation sometimes lets you stay, or move out for only part of the job, if the work can be staged. It isn't always realistic. A second storey or a full rear rebuild usually means moving out as well. Raise it early, because staging changes both the design and the builder's price.
Two of our projects, and one that went the other way
The Symphony was bought to knock down and rebuild as one home for several generations, with 480 m² of internal space on a 963 m² block. It was designed as a long-term home and completed in 2023.
Aurum in Lilyfield is a knockdown-rebuild now under construction. The decision there was to rebuild so the new house could make the most of the site's position.
Meridian in Leichhardt went the other way. A feasibility check showed that extending the federation house, keeping most of its structure and adding a second storey, was a better option than knocking it down. It is now completed.
If you're weighing the two for your own house, our feasibility study looks at the planning controls for your lot, CDC or DA, heritage and what your budget buys, and gives you a written summary. It costs $1,200 + GST and is credited against our design fee if you go ahead. It's the step we'd take before paying for any design. Our page on new homes and knockdown-rebuilds shows how a rebuild runs with us.
What this means for you
- Have the house inspected, and bring in an engineer if there is any sign of movement.
- Get the Section 10.7 planning certificate and check for a heritage listing or conservation area.
- Find out what today's controls allow on your block, for a new house and for an extension.
- Price both routes on the same terms: building work, demolition, site costs, fees and levies, rent and contingency.
- Ask a tax adviser about the main residence rules before you sign anything.
- Make the decision first, then pay for design. Detailed designs of both options are rarely money well spent.
Questions people ask
Is knock down rebuild worth it?
It can be, when the existing house has poor structure, little of its plan works, and current planning controls allow a better house on the block. It is rarely worth it in a heritage conservation area, where demolition needs a DA and councils expect the house to be kept if it contributes to the area. It is also hard to justify when only one part of the house needs work. Price both options on the same terms, including rent and site costs, before you decide.
Is it cheaper to knock down and rebuild than to renovate?
Sometimes, but not as often as people hope. Renovation costs more per square metre, yet you only build what you change. A rebuild adds whole-house demolition, new services and landscaping, and rent for the full build. When a renovation would touch almost every room, the totals can come close; when the work is limited to the back, renovating is usually cheaper.
Can I knock down a house in a heritage conservation area?
Not through a CDC. The state's Demolition Code only allows limited demolition in a heritage conservation area, such as detached structures and internal walls, so demolishing the house needs a development application. Councils generally want houses that contribute to the area kept. Inner West Council, for instance, asks for structural, financial and conservation evidence before it will consider demolishing a contributory house. Expect a long process with an uncertain outcome.
How long do approvals take for a knockdown-rebuild in Sydney?
Complying development can be approved in as little as 20 days, plus neighbour notification where required, if the land and design qualify. A DA takes longer: in September 2026, Inner West Council averaged 96 assessment days and the City of Sydney 53. Add design time before lodging, usually about 4 to 6 weeks plus the consultants' reports, and a construction certificate after a DA.
Do I pay capital gains tax if I knock down my home and rebuild?
It depends on your circumstances, so get advice from a registered tax agent. The ATO's guidance allows you, in some cases, to treat the land as your main residence for up to four years while you build a new home to replace one that was demolished, provided you move in as soon as practicable and live there for at least three months. Other properties you own can affect how that applies.
Sources
- Demolition, NSW Planning Portal
- Complying development, NSW Department of Planning, Housing and Infrastructure
- Approvals, NSW Government
- Council league table, NSW Department of Planning, Housing and Infrastructure
- Inner West DCP Part 2: Heritage, Inner West Council
- About the long service levy for the building and construction industry, NSW Government
- Building or renovating your home, Australian Taxation Office
- Riders Digest 2026, Sydney (PDF), Rider Levett Bucknall
