The slab is the first stage of your build you can actually stand on, and the first one that disappears. Once the concrete is poured, everything underneath it (the plumbing, the steel, the vapour barrier) is out of sight for the life of the house. That makes the days around the pour one of the best times for a site visit, even though there's not much "house" to look at yet.
This guide covers what an owner can usefully check at slab stage, what should be left to professionals, and the photos worth taking while you still can.
Who checks what at slab stage
It helps to be clear about roles, because an owner's walk-around isn't a structural inspection.
- Your building surveyor or certifier (or someone acting for them) typically carries out any mandatory inspection required at this stage in your state, checking compliance with the approved plans and the building code. What's required, and when, varies by state and territory. In NSW, for example, the principal certifier's critical stage inspections include the piers and footings and the slab before it is poured.
- The engineer's design sets out the steel reinforcement, footings and slab thickness. Whether the steel is correctly sized, placed and supported is a technical question for the engineer, surveyor or an independent inspector.
- An independent building inspector, if you engage one, can do a pre-pour inspection for workmanship and defects on your behalf. Pre-pour notice can be short, so if you want one, arrange it with your builder early.
- You, the owner, are best placed to check that it's the right house, in the right place, with the things you asked for.
Before the pour: what an owner can check
If you can get on site after the plumbing and steel are in but before the pour, bring your site plan, your floor plan and any variations. Always follow your builder's site safety rules and arrange visits with them first.
Right house, right place
- The house is oriented on the block the way the site plan shows, with the garage and front entry on the correct side
- The overall footprint looks consistent with your floor plan: garage, alfresco and any bump-outs where you expect them
- Nothing looks obviously off about the position on the block compared to the site plan. You're not measuring setbacks, just noticing anything that clearly doesn't match
Plumbing that's about to disappear
- Pipe positions roughly match where the plans show the kitchen, bathrooms, ensuite, laundry and toilets
- Anything you paid extra for is there: a kitchen island sink, an extra outdoor tap, a relocated toilet, a gas point, a floor waste
- Any changes from signed variations have been picked up. A variation moving the ensuite vanity is easy to miss at this stage and very expensive to fix after the pour
Photos to take
- A wide shot of the whole slab area from each corner
- Every plumbing penetration, with something in the frame showing where it is (a wall line, a corner, a tape measure)
- Any service conduits and where they enter the slab
These photos are useful for years. If you ever need to know where a pipe runs under the floor, for a renovation, a new floor waste or a leak, you'll have a dated record of it.
After the pour: what to look for
- Water pooling around the slab edges or across the site, and how the site drains after rain
- Visible cracking. Some fine shrinkage cracking can occur in concrete, but if you notice cracks, photograph them with something for scale and ask your builder about them in writing. Whether a crack matters is a question for the builder, engineer or an inspector, not something to judge by eye
- Damage to neighbours' fences, footpaths or kerbs. Photograph existing conditions early so any later damage has a clear record
- Rubbish, offcuts or excess concrete left on site
If something doesn't look right
Email your builder or site supervisor the same day. Describe exactly what you saw and where, attach your photos, and reference the plan or variation it relates to. Ask for a written response. Before the pour, it's worth asking for an answer before the concrete goes in, because many problems become much harder to fix afterwards.
Slab stage questions
Can I visit my site at slab stage?
Usually. In Victoria you have a right to reasonable access to your site during construction, even if the contract says otherwise; elsewhere, check what your contract says about owner visits. Wherever you build, construction sites are dangerous, so arrange visits with your builder and follow their site safety rules.
Do I need an independent inspection at slab stage?
It's not always required, but many owners get one, because slab stage is one of the few chances to see work that will be hidden permanently. If you want one, book it early, since pre-pour notice can be short.
What stage comes after slab?
Usually frame stage, when the wall and roof frames go up. It's the next good time for a site visit and another point where things are about to be covered up.
Official sources
Rules differ between states and territories. These official pages explain the parts of this guide that depend on the law in each state; check the equivalent body where you build.
- NSW Planning Portal: the build phase and critical stage inspections: critical stage inspections, including piers and footings and the slab (NSW)
- Consumer Affairs Victoria: building progress: owner site access and written inspection outcomes (Victoria)
