If you love your block, your street and your neighbours, but the house on it no longer works for how you live, a knockdown rebuild lets you keep the address and start again. The question most people ask first is straightforward: what does a knockdown rebuild actually cost in Sydney?
The honest answer is that it depends on the size and condition of your existing house, your block, and the design and inclusions you choose. Here’s what actually drives that cost before you start planning.
What affects your knockdown rebuild cost
A few things move the number more than any other:
- The existing house. Older homes built before 1990 often need licensed asbestos removal as part of demolition, which adds to the cost.
- Site access and slope. A tight block or a sloping site takes more machinery time and site prep than a flat, easy-access block.
- Council requirements. Every block sits under different setback, height and floor space ratio rules, and some need extra reports such as bushfire assessments.
- Your design and inclusions. BuildTec’s Classic, Prestige and Platinum inclusion ranges sit at different price points, so the design and finish level you choose has a direct effect on the total.
We manage demolition, approvals and construction ourselves, and we talk you through what’s driving your cost before you commit to anything, so you understand where your budget is going.
Knock down rebuild vs renovation: which is right for your block?
This is the comparison most people weigh up before they commit to either path.
A renovation keeps your existing structure and can work well for cosmetic updates or smaller changes. But once a renovation starts touching load-bearing walls, wiring or plumbing, older homes often reveal problems that weren’t visible at quoting stage, and costs can climb from there.
A knockdown rebuild removes that uncertainty. You’re building from a clean slate, on land you already know, with a layout designed around how your family actually lives now rather than how a house was laid out decades ago. For older homes needing significant structural change, a rebuild is often the more predictable option, both on cost and on what you end up with.
There’s no single right answer. It comes down to how much of your existing home would need to change, and how much certainty you want over the outcome.
The knockdown and rebuild process, step by step
Here’s what the process generally looks like from decision to handover:
- Choose your design and inclusions. Select a BuildTec design or discuss a custom layout, and choose from our Classic, Prestige or Platinum inclusion ranges.
- Approvals and site reports. Your project needs either a Development Application or a Complying Development Certificate, along with a contour survey, borehole report and BASIX assessment to confirm your block is ready to build on and meets NSW energy and water efficiency requirements. We prepare and lodge this documentation as part of our standard preconstruction process.
- Contracts. This stage includes the HIA Preliminary Agreement and HIA Contract, which set out the scope and terms of your build.
- Demolition and site preparation. Once approvals are through, demolition and any required site works happen before construction starts.
- Construction. Your build follows the same process as any new BuildTec home, with the same trusted trades and joint site inspections at key stages.
- Handover and warranty. After handover, you get a detailed warranty inspection three months in, backed by our 7-year structural warranty.
How long does a knockdown rebuild take?
Once your approvals and demolition are complete, your knockdown rebuild follows the same build timeline as any new BuildTec home. Preconstruction, which covers approvals and finalising your design, typically takes 3 to 6 months. Construction then depends on your design: around 4 months for a single storey home, 7 months for a double storey home, and 5 months for an acreage-style home. Very large luxury designs can run 10 to 18 months. The exact building period for your home is set out in your HIA contract, with an estimated timeframe provided before you sign anything.
Todd des-Baux, Director of BuildTec Homes, has over 20 years of building experience and holds NSW builder’s licence 316011C. He’s involved in every BuildTec project from pre-construction through to handover.
Questions, answered
Straight answers to the questions we hear most before a build begins.
How much does a knockdown rebuild cost in Sydney?
It depends on your block, existing house and chosen design. A site visit gives you an accurate figure for your project.
Is a knockdown rebuild cheaper than renovating?
Not always upfront, but for homes needing significant structural change, a rebuild often avoids the unpredictable costs that renovations can uncover once walls come down.
Do I need council approval to knock down and rebuild?
Yes. Most projects need either a Development Application or a Complying Development Certificate, along with supporting reports like a contour survey and BASIX assessment.
How long does the knockdown and rebuild process take?
It depends on your design. Preconstruction, covering approvals and design finalisation, typically takes 3 to 6 months. Construction then runs around 4 months for a single storey home, 7 months for a double storey home, or 5 months for an acreage design, with very large luxury homes taking 10 to 18 months. Your HIA contract sets out the exact building period before you sign.
Can I choose my own design for a knockdown rebuild?
Yes. You can choose from BuildTec’s home designs, bring your own plans, or work through a fully custom design with our team.
