Site preparation is the stage where budgets are made or broken before a single trade you’d recognise from TV has arrived. It’s also the stage with the widest quote variation in the whole build — because it’s the stage priced against what’s under your block, and nobody can see under your block. This walkthrough covers the sequence, the documents that de-risk it, and the traps that surface here.
What this stage actually contains
- The soil report and contour survey — commissioned before final engineering, not after. The soil classification (A, S, M, H, E, P) drives the slab design, the piering, and a five-figure slice of your budget.
- Demolition and clearing — existing structures, trees (check your approval’s tree protections first), rubbish. Asbestos in anything pre-1990 needs licensed removal and a clearance certificate.
- Site establishment — temporary fencing, sediment/erosion controls, site toilet, temporary power. Certifiers and councils inspect sediment controls; fines land on the owner-builder.
- Service connections — power, water, sewer, stormwater, NBN conduit. Long lead items: authority connections can run weeks, so applications go in early.
- Cut, fill and access — earthworks to design levels. Where fill is placed, it must be certified (compacted and documented), or the slab engineer treats it as uncontrolled and the design cost climbs.
- Set-out — a licensed surveyor pegs the building on the block per the approved siting. Setback errors discovered at frame are catastrophically expensive; discovered at set-out they’re a morning’s work.
The documents that protect this stage
- Soil report + contour survey — before final quotes, so every trade prices the same ground.
- Dial Before You Dig search — free, mandatory in practice; hitting a service is a bad first week.
- Demolition approvals and asbestos clearance — kept in the file; buyers and certifiers ask.
- Fill compaction certificates — if fill goes in, certification follows it in.
- The surveyor’s set-out certificate — your proof the building sits where the approval says.
Money behaviour at this stage
Siteworks is where provisional sums live, and PS items reprice at cost-plus with no ceiling. Push for fixed prices on everything the soil report makes knowable, and hold a genuine contingency for what it doesn’t — the contingency self-check pressure-tests whether yours matches your block’s risk profile.
What “ready for slab” means
The stage is done when: levels match the design, fill is certified, services are stubbed where the slab drawings show them, sediment controls are standing, and the set-out is certified. Rushing any of these hands the slab crew a reason for a variation — and slab-stage variations arrive with a concrete truck’s urgency.
Next in the sequence: the slab stage, where the certifier’s first mandatory inspection anchors everything.
Before you get here
The Pre-Start Review checks your siteworks scope, soil report and budget lines against each other before the excavator’s booked — $790, one week, and this stage stops being the wild card.