Costs, Price Drivers and 2026 Rules
Home renovation cost estimator for Australia: what drives the price and how to build your range
How Australian renovation costs are built up, the drivers that move them, illustrative ranges by project type and the 2026 rules to check before you sign.
A home renovation in Australia costs what its scope, size, finish level, structural work and location add up to, plus professional fees, approvals, GST and a contingency. There is no single price per room. The fastest way to a realistic number is to measure the floor area of the work, pick an illustrative rate band for your project type and finish level, add fixed costs such as design and approvals, and then add 10% to 20% contingency. That gives you a planning range you can test against two or three written quotes from licensed builders.
This guide is the overview for the Costs, Price Drivers and 2026 Rules section. Every dollar figure below is an illustrative example built from the stated assumptions, not a quote, survey or market price.
How a renovation price is built
A builder's quote is usually the sum of five layers. Knowing them helps you see where two quotes differ.
| Layer | What it includes | Why it varies |
|---|---|---|
| Direct trade costs | Demolition, carpentry, plumbing, electrical, waterproofing, tiling, plastering, painting | Number of trades, hours on site, access |
| Materials and fittings | Framing, sheeting, tiles, cabinetry, benchtops, tapware, appliances | Finish level and supply chain |
| Preliminaries | Site protection, skip bins, scaffolding, temporary fencing, toilet hire, supervision | Job length and site constraints |
| Builder's margin | Overheads, insurance, warranty risk and profit | Business size and risk of the job |
| Statutory and professional costs | Design, engineering, certifier or council fees, home warranty insurance, levies | State, council and approval pathway |
GST at 10% applies on top if the builder is registered for GST, and most homeowner quotes should be stated including GST. See GST on renovations.
The cost drivers that matter most
1. Wet areas. Kitchens, bathrooms and laundries pack plumbing, electrical, waterproofing, tiling and cabinetry into a small space, so their cost per square metre is several times that of a living room. Adding a bathroom to an extension changes its cost far more than adding a bedroom.
2. Structural work. Removing load-bearing walls, adding a storey, underpinning or building on reactive clay all bring engineering, steel beams and longer programmes. Read the second-storey guide for how structure dominates that budget.
3. Finish level. The same bathroom layout can be budget, mid-range or premium depending on tiles, tapware, vanity and niche details. Finish level is the driver you control most directly.
4. Location and access. Labour rates, travel time and material delivery differ between capital cities and regional towns. Steep blocks, narrow side access, terraces with no rear lane and apartments with lift bookings all add time.
5. Age and condition of the house. Older homes may contain asbestos, outdated wiring, rotten subfloors or no waterproofing at all. These are often found only once walls are opened, which is why contingency matters.
6. Approvals and certification. Like-for-like internal work often needs no planning approval, but extensions, second storeys and granny flats need planning and building approvals. See council approvals, certifiers and fees.
7. Market conditions. Trade availability and material prices change over time. The ranges here are not indexed to any data series, so treat them as a structure, not a forecast.
Illustrative ranges by project type
The bands below are the same ones loaded into the renovation cost estimator. They assume a metropolitan job with licensed trades, GST and the builder's margin included. They are assumptions for planning, not market data.
| Project type (illustrative) | Per m² band, incl. GST | Example size | Example range before fixed costs |
|---|---|---|---|
| Bathroom, mid-range | $4,500 to $7,500 | 6 m² | $27,000 to $45,000 |
| Kitchen, mid-range | $2,500 to $4,500 | 12 m² | $30,000 to $54,000 |
| Ground-floor extension, mid-range | $3,000 to $5,000 | 30 m² | $90,000 to $150,000 |
| Second-storey addition | $3,800 to $6,500 | 60 m² | $228,000 to $390,000 |
| Detached granny flat, standard | $2,500 to $4,200 | 60 m² | $150,000 to $252,000 |
| Cosmetic refresh | $500 to $1,400 | 80 m² | $40,000 to $112,000 |
Worked example (illustrative). A mid-range bathroom of 6 m²: 6 x $4,500 = $27,000 and 6 x $7,500 = $45,000. Add $3,000 of fixed costs (say design advice and a waterproofing inspection) to get $30,000 to $48,000. Add a 10% contingency on the top of the range, $4,800, and plan for up to about $52,800.
The full method, including how to price fixed costs and items outside the contract, is in how to build a renovation estimate step by step.
Project guides in this section
- Kitchen renovation cost: cabinetry, benchtops, layout changes and appliance packages.
- Bathroom renovation cost: waterproofing, tiling and why small rooms are expensive per m².
- Home extension cost: footings, roof tie-ins and what a ground-floor addition involves.
- Second-storey addition cost: structure, temporary roofing and moving out.
- Granny flat cost: secondary dwellings, services connections and state approval pathways.
- Knock-down rebuild versus renovate: a decision framework, not a price list.
- Renovation rules by state: licences, written contracts, deposits, cooling-off and home warranty thresholds.
Rules to check before you sign (2026)
Renovation rules are made by each state and territory. Three examples show how much they differ:
- NSW: a written contract is required for residential building work over $5,000 including GST, the deposit is capped at 10%, and home building compensation cover is required for work over $20,000.
- Victoria: a major domestic building contract and a registered builder are needed for most work over $10,000, and domestic building insurance applies above its threshold. Reforms to the Domestic Building Contracts Act 1995 commence by 1 December 2026.
- Queensland: a QBCC licence and home warranty cover generally apply to building work over $3,300.
Details, cooling-off periods and other states are in renovation rules by state.
When to get professional help
Get a building designer or architect involved once the scope includes structural changes, an extension or a second storey. A structural engineer is needed for load-bearing changes. If you are unsure about a contract clause, a building lawyer or your state's free advisory service can review it before you sign.
FAQ
Is a cost per square metre reliable?
It is a planning shortcut. It works best for whole extensions and new floor area, and worst for small wet areas, where fixtures and trades rather than area drive the price.
Why do quotes for the same job differ so much?
Usually because they price different scope, different allowances or different risk. Use the quote comparison checklist to line them up.
Should I include GST in my estimate?
Yes. Homeowners generally cannot claim GST back, so plan in GST-inclusive dollars.
Are the ranges on this site current market prices?
No. They are illustrative bands built from stated assumptions. Use them to structure your thinking, then rely on written quotes.
Sources
- Building Commission NSW, via NSW Government — home building contracts, deposits and insurance in NSW
- Building and Plumbing Commission (Victoria) — registration, domestic building insurance and disputes
- Consumer Affairs Victoria — domestic building contract law updates
- Queensland Building and Construction Commission — licensing, contracts and home warranty in Queensland
- Australian Building Codes Board — the National Construction Code
