How much does a home extension cost in Melbourne? (2026)
Home extensions in Melbourne run $150,000 to $380,000 depending on whether you are going up or out, and how much structure is involved. This guide breaks down what each type of extension costs, what drives the price, and what a good contract for an extension project actually needs to include.
Home extension cost breakdown — Melbourne 2026
| Extension type | Price range | What is included |
|---|---|---|
| Rear ground floor | $150,000 – $280,000 | 40 to 60m2 of new living area. Open-plan kitchen/dining/living, connection to existing structure, new roof, insulation, finishes. |
| First floor addition | $200,000 – $380,000 | Full upper level including structural frame, staircase, bedrooms, bathroom, roofing, internal finishes. More expensive per m2 due to structural complexity. |
| Granny flat / studio | $90,000 – $180,000 | Self-contained detached or semi-detached dwelling. Kitchen, bathroom, living area. Subject to local council maximum size limits (typically 60m2). |
| Garage conversion | $40,000 – $90,000 | Converting an existing garage to a habitable room. Insulation, new floor, window installation, electrical, plastering, finishes. Permit required. |
Prices for metropolitan Melbourne. Heritage overlays, difficult site access, and council setback restrictions all affect final cost. These ranges exclude planning and building permits ($10,000 to $30,000 typically) and structural engineering.
What drives the cost of a home extension
Connection to the existing structure
The junction between the old building and the new extension is the most complex and expensive part of the job. Matching roof pitches, tying into existing foundations, penetrating existing walls, and maintaining weatherproofing at the join all take skilled tradespeople and careful sequencing. A poorly designed or built connection is where extensions fail — leaks at the junction or cracking at the tie-in are common problems with fast or cheap builds.
Site access and slope
A rear extension on a flat allotment with lane access is straightforward to build. A rear extension on a sloped block with no side access requires concrete pumping, crane lifts for structural materials, and significantly more labour time. Concrete pumping alone adds $3,000 to $8,000 to the slab cost. Always ask how the builder plans to get materials to the site before you compare quotes.
Planning permit timeline and complexity
Melbourne councils vary significantly in how they process planning applications. Inner-city councils (Yarra, Moreland, Moonee Valley) can take 4 to 8 months for a complex application. Some councils require neighbourhood notification, which can trigger objections and VCAT hearings. A builder who has worked repeatedly in your specific council area understands what designs get approved quickly and what triggers pushback.
Finish level inside the extension
The structure costs the same regardless of finish level. What varies is everything inside: flooring, cabinetry, bathroom fittings, kitchen joinery, lighting, and joinery details. A standard kitchen and bathroom in a rear extension adds $45,000 to $75,000. Mid-spec adds $70,000 to $100,000. Full-spec adds $100,000 and above. Get these priced separately so you know where your budget is going.
Common questions
How much does a home extension cost in Melbourne?
A ground floor rear extension in Melbourne runs $150,000 to $300,000 depending on size and finish. A 40 to 60m2 addition with open-plan kitchen and living, new bathroom, and connection to existing structure typically costs $170,000 to $240,000 at mid-spec. First floor additions cost more due to structural requirements: $200,000 to $380,000. Granny flats and studio additions run $90,000 to $180,000.
Do I need planning permission for a home extension in Melbourne?
Most home extensions in Melbourne require both a planning permit (from your local council) and a building permit (from a registered building surveyor). Heritage overlays, neighbourhood character overlays, and setback rules all affect what you can build and how close to the boundary. Some councils in Melbourne's inner west and inner north have stricter controls. The permit process typically takes 3 to 6 months. Any builder who tells you 'we will sort out the permits after we start' is not telling you the full picture.
How long does a home extension take to build in Melbourne?
From signing the contract to handover: 8 to 16 months for most ground floor extensions. This includes 3 to 6 months for planning and building permits, 1 to 2 months for design and documentation, and 3 to 6 months of construction. First floor additions and double-storey extensions sit at the higher end. A written construction programme with a fixed handover date is a condition worth including in your contract.
Is a home extension worth it compared to moving?
In Melbourne's inner west and inner north, where property prices are high and good stock is limited, extending is almost always cheaper than buying a larger home. A rear extension adding 40 to 60m2 of quality living space typically costs $170,000 to $240,000. The same additional floor area in the same suburb costs multiples of that in the property market. The calculation changes for outer suburban locations where land is cheaper and larger homes more available.
What is the cost per square metre for a home extension in Melbourne?
Home extensions in Melbourne run $3,000 to $5,500 per m2 of new floor area, depending on complexity, finish level, and site conditions. This figure includes structure, waterproofing, roofing, windows, insulation, internal fit-out and finishes. It does not include planning permits, structural engineering, or connection to existing services, which typically add $20,000 to $50,000 to the total. Per-m2 rates are a useful guide but not a quote — site conditions vary too much.
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