New build rough-in plumbing cost: what builders & owner-builders pay in 2026

Rough-in plumbing is the work that disappears behind your walls — drainage stacks, water service, gas line, hot water flow-and-return, vents and slab penetrations. Get it wrong and you're chasing leaks, low pressure and code failures for the life of the home. Get it right and the fit-off becomes the easy part.

Here's what rough-in actually costs for a Melbourne new build or major renovation in 2026, and how it compares to fit-off and final connection.

How rough-in is priced

Three pricing models are common in Victoria: per-fixture, per-outlet, and lump sum. Owner-builders are usually quoted lump sum; volume builders work on schedules of rates. The fixture model is the most transparent for renovators because you see exactly what each tap, toilet and drain costs.

Sample budgets for typical Melbourne builds

Build type	Typical fixtures	Rough-in 2026 price
Single-bathroom unit	8 fixtures	$5,800 – $7,400
Standard 3-bed, 2-bath house	16 fixtures	$11,500 – $15,500
4-bed, 3-bath with butler's pantry	22 fixtures	$16,500 – $22,000
Knock-down rebuild, 5-bed	28+ fixtures	$22,000 – $32,000
Townhouse (per dwelling, 4 in row)	14 fixtures	$9,800 – $13,500

What's included vs excluded — read carefully

Usually included: internal drainage and venting, hot & cold water rough-in, gas rough-in (one appliance), HWS bracketry, fixture tail-outs, slab set-out, hydrostatic testing.

Usually excluded: water authority tapping fee, sewer/stormwater connection to council asset, civil excavation outside the slab footprint, gas meter upgrade, additional gas appliance points, isolation valves at every fixture (we recommend, but quote separately).

Always ask: who pays for the temporary site water? It's small, but a regular argument.

How to compare two rough-in quotes fairly

Stack the line items side-by-side using these questions: How many fixtures? What pipe material — copper, PEX-A, multi-layer? Are isolation valves included at every fixture? Brass tail-outs or chrome? Pressure-tested to what kPa for how long? Is the water-efficiency rating documented? Is a VBA compliance certificate included?

### Frequently asked

Q. How long does rough-in take?

A standard 3-bed house is typically 3–5 days on site, plus return visits before slab pour and before plaster.

Q. Should I use copper or PEX?

PEX-A with brass press-fittings is the modern standard — faster, fewer joints, freeze-tolerant. Copper still wins for visible runs and external service lines.

Q. Is the gas rough-in separate?

It's usually included in the lump sum but listed separately. A standalone gas rough-in for a renovation is typically $1,200–$2,400.

CALL TO ACTION

Building or renovating? Send us your plans on email — we'll return a fixture-by-fixture rough-in quote within 3 business days, with a clear inclusions/exclusions list. Call 0411 234 567.