The decision frame
The build-under-versus-knockdown question is rarely a pure cost calculation. It's a mix of structural condition, planning constraints, sentiment value, neighbourhood character and how the project sequences against your life stage.
When build-under tends to win
- The upstairs structure is sound and worth preserving
- The property sits in a character or heritage overlay that restricts replacement
- The first floor has good ceiling heights and original features worth keeping
- You're willing to manage the structural complexity of working over a 100-year-old timber frame
When knockdown rebuild tends to win
- Termite, rot or structural damage means the upstairs needs more than half its frame replaced
- The property is not in a character overlay (rare in inner Brisbane)
- You want a contemporary plan the existing footprint can't accommodate
- You have a builder willing to fixed-price a new build and don't want owner-builder risk
Costs at a high level
A full Brisbane knockdown rebuild typically prices in the same band as a raise and build-under once you include demolition, slab, two-storey build and external works. The cost gap is often smaller than expected. The risk profiles are very different.
Our Coorparoo build-under cost $331,510 (2018-2020). See the full breakdown.
The hidden tax: time
Both options take similar elapsed time on site. Where they differ: build-under projects often have more variation risk because you're working with an existing structure, while knockdowns have more planning approval risk in heritage-sensitive Brisbane suburbs.
