Most cost surprises on a build are not surprises at all — they are line items nobody priced at the start. Here is how a typical residential budget actually splits, and where it tends to move.
Structure is not where the money goes
Foundation, frame and slab usually land around 35–40% of a build. It feels like the big number because it happens first and it happens fast, but it is the most predictable part of the job. Steel and cement prices are public, quantities come straight off the drawings, and there is very little room for interpretation.
Finishes are where budgets move
The same floor plan can vary by 40% on finishes alone. Tile, joinery, sanitaryware, hardware and paint are all specified late, chosen emotionally, and quoted per unit — which is exactly the combination that lets a budget drift.
- Lock your tile and sanitaryware selections before the slab is poured
- Ask for a per-room finish schedule, not a lump sum
- Price the second-choice option for every major selection
The line items people forget
Roughly 12% of a build sits in items that never appear on the first estimate.
Site clearing, soil testing, temporary power and water, statutory approvals, waste removal, and the final deep clean. None of them are optional and all of them are easy to leave out of an early quote.
What to ask for
Ask any contractor for a stage-wise payment schedule tied to *completed work*, not to dates. If the schedule is honest, the numbers behind it usually are too.
