What happens if drain positions are wrong at the slab stage of a Melbourne new build?

If drain pipe positions are incorrect before the concrete slab is poured and the error is not caught during the pre-pour inspection, correcting them after the slab is poured requires jackhammering the concrete, repositioning the pipes, and repouring. This is expensive and causes significant build delays. Pre-pour plumbing inspection by a certified plumbing inspector is mandatory in Victoria precisely to catch these errors.

How many times does a plumber visit during a Melbourne new home build?

There are typically three distinct plumbing phases: slab plumbing (before concrete pour), rough-in (during frame stage, including all wall pipe runs and external drainage), and fit-off (after tiling and painting, installing all tapware, fixtures, and appliances). Some projects require additional visits for inspections or if trades are separated. A licensed plumber must certify each stage.

What is a Certificate of Compliance for plumbing in a new Melbourne home?

A Certificate of Compliance (CoC) is issued by a licensed plumber after completing regulated plumbing work, certifying that the work meets Victorian plumbing standards. For new builds, a CoC is required at each plumbing stage. The CoC is an important legal document — keep it with your property records. It is required when selling the property and for insurance purposes.

Plumbing for New Builds in Melbourne: What to Expect at Each Stage

New home construction in Melbourne involves plumbing work at multiple stages. Understanding what happens at each stage helps you manage your build schedule, ask the right questions, and avoid costly delays.

Stage 1: Slab Plumbing (Before the Concrete Pour)

This is the most critical stage. Before the concrete slab is poured, the plumber installs all drain pipes, waste pipes, and sewer connections beneath the slab. Every drain outlet — toilets, showers, baths, basins, kitchen sink, laundry — must be positioned exactly according to the architectural plan. Once concrete is poured, changing anything requires jackhammering and significant cost. The plumber also installs the conduit for the water supply pipes where they penetrate the slab. This stage requires an inspection by a plumbing inspector before the concrete is poured.

Stage 2: Rough-In (During Frame Stage)

After the frame is erected, the plumber runs all the water supply pipework through the walls and ceiling — hot and cold to every fixture position. This includes the internal hot water system connection, all bathroom and kitchen supply lines, laundry connections, and outdoor tap points. The gas rough-in also occurs at this stage for all gas appliances. External drainage connections to the sewer and stormwater are completed. Another plumbing inspection occurs at the end of this stage before walls are lined.

Stage 3: Fit-Off (After Painting and Tiling)

After all wall lining, painting, and tiling is complete, the plumber returns for fit-off. This involves installing all tapware, mixers, showerheads, toilets, basins, baths, kitchen sink, dishwasher connection, laundry trough, the hot water system, and any gas appliances. The plumber tests all connections, checks water pressure and flow at every outlet, lights pilot lights, and completes final certification. A Certificate of Compliance is issued for all plumbing work.

Common Delays in New Build Plumbing

The most frequent causes of plumbing-related delays in Melbourne new builds are: late or incomplete architectural plans at slab stage, changes to fixture positions after slab is poured (costly rectification), tapware or fixtures not on-site when the plumber arrives for fit-off, and disputes over the boundary between plumber and electrician on hot water system installation. Good coordination between your builder, plumber, and other trades prevents most of these.

Sedcon Plumbing — New Build Plumbing Across Melbourne

We work with builders and owner-builders across Melbourne on new residential construction. Call 0468 013 012 to discuss your new build plumbing needs.