Mandatory critical stage inspections in NSW

What it is

A critical stage inspection is a physical inspection of the building work at points prescribed by the Environmental Planning and Assessment (Development Certification and Fire Safety) Regulation 2021. The principal certifier appointed for the development must carry out (or arrange) each inspection before the next stage of work proceeds. The list of mandatory stages is set in Schedule 4 of that Regulation.

For Class 1 (detached houses) and Class 10 (sheds, garages, carports) buildings in NSW, the standard sequence is:

• Before pouring any in-ground reinforced concrete
• After excavation for, and prior to placement of, any footings
• Prior to pouring any reinforced concrete slab or footing
• Prior to covering of the framework (wall, floor, ceiling and roof framing)
• Prior to covering waterproofing in wet areas
• Prior to covering any stormwater drainage connections
• After the building work has been completed and prior to issue of any Occupation Certificate

Why it matters for compliance risk

NSW Fair Trading and the NSW Building Commissioner audit certifier files heavily. The pattern that triggers enforcement is consistent: a builder requests sign-off after the trade has already covered the work, the certifier issues a retrospective inspection record, and the file goes pink at audit. Under section 6.7 of the Environmental Planning and Assessment Act 1979, the principal certifier cannot issue an Occupation Certificate unless each mandatory inspection has been completed and recorded.

Frame inspection

The framing stage is the high-risk one. Wall and roof framing must be inspected before any sarking, cladding, plasterboard or insulation conceals the structure. If a builder books the frame inspection after gyprock starts, the certifier has two bad options: refuse and force removal of linings, or issue a record they cannot defend at audit.

Waterproofing inspection

Wet area waterproofing must be inspected before tiling. AS 3740 compliance and the membrane installer's statement are checked at this point. A high share of NSW residential defects claims start here, so an absent inspection record on a leaking shower is hard to rebut.

Stormwater inspection

Stormwater drainage must be inspected before backfill. This stage gets skipped on small additions because the trade is in and out in a day.

What the builder must do

The builder should give the principal certifier at least 48 hours notice of each inspection, in line with the certifier's terms of appointment. The Environmental Planning and Assessment Act 1979 makes it a contravention to carry out work in a manner that prevents inspection at a critical stage. Penalties apply to the builder, not the certifier, for proceeding past a stage without inspection.

Records

Each inspection generates an inspection record kept on the certifier's file under section 6.6 of the Act. NSW Fair Trading can require production of these records. A missing record at audit is treated as if the inspection did not occur.

Where TradeLens should flag risk

Audit triggers worth tracking:

• Stage sequence breaks: stormwater signed off after slab pour, frame signed off after lining
• Inspection records dated after the day work was covered
• Same-day sign-off of multiple stages (suggests retrospective record keeping)
• OC application submitted with one or more critical stage records missing
• Builder substitutions of certifier mid-project without a new appointment in writing under the Building and Development Certifiers Act 2018