Hiring a building certifier: who they are and when you need one

What a certifier actually does

A certifier's job has three parts. Before work starts, they assess your plans against the Building Code and issue the building approval. During construction, they carry out mandatory inspections at key stages — footings, frame, waterproofing and so on, depending on the project. At the end, they issue the final certificate that says the building is approved for use.

What they don't do is design anything or manage your builder. If the deck fails inspection, the certifier tells you what's non-compliant; fixing it is between you and your tradie. They're also distinct from a building consultant or inspector you might hire for a pre-purchase check — a certifier's role is statutory, and projects like decks, carports, sheds, pool fences, extensions and new homes generally can't proceed legally without one.

How the fees work

Certifiers quote a fixed fee per project that scales with size and complexity. Indicatively, certifying a small structure like a deck or carport sits in the hundreds, a renovation or extension in the low thousands, and a full new-home service higher again — the calculator on this page reflects those bands. The fee normally bundles the plan assessment, the scheduled inspections and the final certificate.

What trips people up is what sits outside the fee. Council lodgement charges and government levies are usually on top, and if work fails an inspection, the re-inspection is typically billed per visit. Ask for the inclusions in writing: how many inspections, which certificates, and exactly which government charges are extra. Fees also vary noticeably between states, so a mate's number from interstate isn't a useful benchmark.

Checking registration and choosing well

Certification is regulated work everywhere in Australia — every legitimate certifier holds a state registration or licence, and they'll give you the number without hesitation. Check it against your state's public register, and confirm they're accredited for your class of building; residential work is the bread and butter, but it's a fair question.

Beyond the paperwork, the practical differences are responsiveness and clarity. A good certifier turns plan assessments around promptly, books inspections without weeks of delay, and explains non-compliance in plain English so your builder knows exactly what to fix. Engage them before work starts, not after — retrospective approval of unapproved work is slower, more expensive and not always granted.

Mistakes to avoid

The expensive certifier mistakes all happen early. Building first and seeking approval later is the classic, and it can mean pulling compliant-looking work apart so hidden stages can be inspected. The second classic is assuming your builder has certification handled — sometimes they do, but the approval is ultimately your responsibility as the owner, so confirm rather than assume.

• Starting work before the approval is issued, then paying for retrospective certification
• Assuming the builder engaged a certifier without seeing it confirmed in writing
• Not asking how many inspections the fee includes and what a re-inspection costs
• Forgetting council lodgement fees and levies sit on top of the certifier's fee
• Hiring on price alone when slow inspection turnarounds can stall your whole build
• Skipping the register check on the certifier's registration number