Knockdown rebuild or renovate

Both paths keep the thing you actually bought, which is the location. What they differ on is how much of the existing building constrains what you end up with, and how predictable the cost is.

Question one: can you demolish?

This is a planning question, not a budget one, and it is the one to answer first. A heritage control, a conservation area, a character overlay or a significant tree can make demolition difficult or impossible. Being inside a conservation area can reach a house that is not itself listed. Our area pages report the heritage and overlay mapping for the suburb so you know whether the question applies before you commission anything.

Question two: what are you actually keeping?

A renovation keeps the structure, and with it the floor level, the footing system, the wall framing and whatever is inside the walls. If the existing house is sound and the layout suits, that is a genuine saving. If the structure is poor or the level is wrong, you can spend rebuild money to get a compromised result.

Question three: how much do you want to change?

Renovations are most efficient when they work with the existing structure and least efficient when they fight it. Moving wet areas, changing the roof line and removing structural walls each erode the saving. Past a certain point a rebuild is both cheaper and better.

Predictability

This is the difference people underestimate. A new build on a cleared site is a known quantity: the design is drawn, the site is classified, the scope is visible. A renovation involves opening up an existing building, and what is behind the wall is not fully known until it is open. Renovation budgets carry more variation risk, and the contingency should reflect that.

Timeline

Demolition adds time at the front — service disconnections, asbestos assessment where the era suggests it, the demolition approval itself. Renovation often adds time in the middle, when something is uncovered. Neither is reliably faster.

What we would ask a builder

Have you done both on this kind of house, in this council area? What did you find behind the walls last time? And for a renovation specifically: what is your process when the scope changes mid-job? See questions to ask a builder and how a knockdown rebuild runs.