A knock down rebuild lets you stay in the suburb you love while getting a new home designed around how you live. It can also be one of the biggest financial decisions you make, and the build price is only part of the total. This guide covers what to budget for so there are fewer surprises.
1. Pre-construction costs
- Design: architect or building designer fees.
- Reports: survey, geotechnical report, and often arborist, BASIX, bushfire or flood reports depending on the site.
- Engineering: structural and stormwater design.
- Approval fees: development application or complying development certificate fees, and certifier costs.
2. Demolition
Demolishing the existing house, including a hazardous materials survey, licensed asbestos removal and clearance, service disconnections, and removal of slabs, footings, pools, driveways and trees as required.
3. Site costs
Often the most underestimated part. Site costs include excavation and site cut, retaining walls on sloping blocks, rock removal, piers where soil requires them, stormwater and sewer connections, and any upgraded electrical or water services. Sloping, rocky or reactive clay sites can add significantly to the budget.
4. The build
The new home itself: structure, roof, windows, internal fit-out, kitchens, bathrooms and finishes. Single storey versus double storey, the size of the home, the level of finish and the complexity of the design are the biggest variables.
5. External works
Driveways, paths, fencing, landscaping, retaining walls and the council vehicle crossing are often excluded from build contracts. Check what is included.
6. Living costs during the build
Rent or temporary accommodation, removalists and storage for the duration of approvals, demolition and construction.
Knock down rebuild or renovate?
If the existing home has structural problems, a poor layout, or would need major work to services, a rebuild is often better value than extensive renovation. If the home is structurally sound and you mainly need more space, an extension or first floor addition may cost less. A builder's site visit can help you compare both options honestly.
How to avoid budget blowouts
- Get the site costs assessed early, not after the contract.
- Read exclusions and provisional sums carefully.
- Budget a contingency for the unexpected.
- Use one builder for demolition, site works and the build where you can, to avoid gaps between contractors.
Talk to a builder who handles the whole job
We handle demolition (Licence AD214430), site works and the build under one contract. See our knock down rebuild service or book a free site assessment.
Frequently asked questions
How long does a knock down rebuild take in Sydney?
It varies widely. Design and approvals can take months, demolition usually takes a few weeks including asbestos removal, and construction of a new home commonly takes many months depending on size and complexity.
Do I need a DA for a knock down rebuild?
Some knock down rebuilds can be approved as complying development, which is faster, while others need a development application, for example on heritage, flood or bushfire affected land.
What are site costs in a knock down rebuild?
Site costs cover preparing the land for the new home: excavation, retaining, rock removal, piers, and service connections. They depend heavily on slope, soil and access.
