Costs, Price Drivers and 2026 Rules
Bathroom renovation cost in Australia: why small rooms cost so much per square metre
What drives bathroom renovation costs in Australia, illustrative ranges for budget and mid-range finishes, waterproofing rules, strata approvals and quote traps.
A bathroom is usually the most expensive room per square metre to renovate in an Australian home because a few square metres need demolition, plumbing, electrical, waterproofing, screeding, tiling, glazing, carpentry and painting, each a separate trade visit. The main cost drivers are whether the layout changes, the tile area and tile choice, the fixtures, the condition of the floor and walls behind the old tiles, and whether the room is in a house or a strata apartment. As illustrative planning figures, a 6 m² mid-range bathroom might fall around $27,000 to $45,000 including GST before fixed costs, and a budget refresh on the same layout around $18,000 to $27,000. These are assumptions for budgeting, not quotes.
This guide sits under the renovation cost overview.
Why bathroom costs are front-loaded
Most of a bathroom's cost is fixed by the number of trades and the sequence they must follow, not by its size. A 4 m² ensuite and an 8 m² family bathroom need the same trades; the larger room just uses more tiles. That is why per-m² rates for bathrooms are several times those for living areas.
Typical sequence:
- Strip-out and waste removal, including any asbestos-containing sheeting found in older homes (licensed removal where required).
- Plumbing rough-in: moving or replacing water and waste pipes.
- Electrical rough-in: lighting, exhaust fan, heated towel rail, power points.
- Carpentry and sheeting: fixing frames, wet-area board, niches.
- Screed and falls to the floor waste.
- Waterproofing, then a curing period, often followed by an inspection or flood test.
- Tiling and grouting.
- Fit-off: vanity, toilet, tapware, shower screen, mirror, accessories.
- Painting and final clean.
Illustrative ranges
| Option (illustrative) | Per m² band, incl. GST | 6 m² example | What changes |
|---|---|---|---|
| Budget, same layout | $3,000 to $4,500 | $18,000 to $27,000 | Standard tiles to set heights, off-the-shelf vanity, framed screen |
| Mid-range | $4,500 to $7,500 | $27,000 to $45,000 | Floor-to-ceiling tiles, wall-hung vanity, frameless screen, niche, possible minor layout change |
Premium bathrooms with freestanding baths, large-format tiles, underfloor heating or relocated toilets can go well beyond these bands. Toilets are often the most expensive item to move because the waste line has a minimum fall.
Worked example (illustrative)
A 6 m² main bathroom in a 1970s house, mid-range finish, layout unchanged:
- Area x rate: 6 x $4,500 = $27,000 to 6 x $7,500 = $45,000.
- Fixed costs: asbestos test of wall sheeting $500, and a new switchboard circuit for a heated towel rail $700. Total $1,200.
- Range: $28,200 to $46,200.
- Contingency of 15% on the high end, reflecting an older house: $6,930.
- Planning budget: up to about $53,130.
You can reproduce this with the renovation cost estimator and the contingency calculator.
Waterproofing: the line you should never trim
Failed waterproofing is one of the most common bathroom defects, and the damage often shows up only after the warranty period for minor defects. The National Construction Code sets wet-area requirements through its referenced standard for waterproofing of domestic wet areas, and states add their own licensing rules:
| State | What to check |
|---|---|
| NSW | Whether the waterproofer holds a contractor or qualified supervisor licence for waterproofing, or works under the licensed builder; check it on the Service NSW licence register |
| Victoria | Whether waterproofing must be done by a registered practitioner for your job; the Building and Plumbing Commission explains current trade registration |
| Queensland | Whether the waterproofer holds the QBCC licence class for waterproofing, which applies to work above the licence threshold |
Rules on which trades need their own licence change, so check your regulator before you accept a quote that lists an unlicensed subcontractor.
Ask for:
- the waterproofing product and the membrane system to be named in the quote;
- a written waterproofing certificate at completion;
- photos of the membrane before tiling, which help in any later dispute.
House versus apartment
In a strata apartment, bathroom renovations often need owners corporation or strata committee approval, because waterproofing and pipes can affect common property. Some by-laws require a licensed builder, specific insurance, working hours and a bond. Approval can take weeks, so budget time as well as money. In NSW, strata renovation categories (cosmetic, minor, major) are set by the Strata Schemes Management Act 2015; your by-laws and the NSW strata pages explain which applies.
Mistakes to avoid
- Accepting a lump sum with no breakdown. If anything changes, you cannot price a variation fairly.
- Low tile allowances. A provisional sum of $40 per m² for tiles you want at $90 per m² costs you the difference plus margin. See prime cost and provisional sums.
- Skipping the exhaust fan duct. A fan that vents into the roof space rather than outside can cause mould.
- Ignoring the floor. Rotten timber floor framing under an old shower is common; ask how the builder will price it if found.
- Paying for fixtures up front to a builder who then stalls. Keep payments tied to progress, as explained in deposits and progress payments.
Which rules apply to a bathroom job
A bathroom renovation usually exceeds the written contract thresholds in every state, so you should expect a written contract, a licensed or registered builder, a capped deposit and, above the thresholds, home warranty insurance. For example, a $35,000 bathroom in NSW would need a large job contract and an insurance certificate under the Home Building Compensation Fund because it is over $20,000. In Queensland, it is well over the $3,300 licence and home warranty threshold. See renovation rules by state and home warranty insurance by state.
FAQ
Can I tile over the old tiles to save money?
Sometimes, but it raises the floor, hides waterproofing problems and may not be acceptable under the waterproofing standard. Most builders strip to the frame for a full renovation.
How long does a bathroom take?
Commonly a few weeks, mainly because of membrane curing and the trade sequence. Ask for a written programme.
Is an ensuite cheaper than a main bathroom?
Usually slightly, because it is smaller, but the cost per square metre is often higher because the same trades are needed.
Do I need a separate plumber's certificate?
Plumbing work must be done by a licensed plumber, who usually lodges a compliance certificate with the state plumbing regulator. Ask for a copy.
Sources
- Australian Building Codes Board — National Construction Code wet-area requirements
- Building Commission NSW, via NSW Government — contracts, specialist work and strata renovations
- Building and Plumbing Commission (Victoria) — practitioner registration and plumbing
- Queensland Building and Construction Commission — licence classes and home warranty
- Asbestos and Silica Safety and Eradication Agency — asbestos in older homes
