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Granny flat costs in Victoria

From Modular Living Australia — the independent knowledge base Last updated: 8 Oct 2026

Published Victorian figures put a turnkey granny flat at about A$140,000–A$280,000 and a two-bedroom of 50–60 m² in Melbourne at A$160,000–A$260,000, while an owner-managed kit route is put at A$120,000–A$180,000 finished.^[1][2][4] These are commercial guidance, not independent survey data.

Victoria is the state where the published cost figures for secondary dwellings diverge most, and where a single planning threshold — 60 square metres — does more to shape the budget than any design decision. This guide sets out what the published ranges say, why they disagree, and the two Victorian-specific cost drivers that appear in almost every project: soil and energy compliance.

What the published sources say §

None of these is independent survey data. Two are published by builders selling the product, one by a kit supplier, one by a drafting service, and the remainder by information and quote-comparison sites carrying commercial relationships.

Sixty square metres is a budget decision, not a design one §

Victorian pricing clusters around 60 m² because the planning system puts a threshold there. A builder's guide states that under amendment VC253 a property over 300 m² can build a small second dwelling of 60 m² or less without a planning permit^[3]; an industry site describes the same reform and notes that planning approval can still be required where overlays apply to the land^[1].

The cost consequence is worth stating plainly. A design at or under the threshold avoids a planning permit application, which one source puts at 6 to 12 weeks and A$1,500 to A$5,000 in council fees^[5]. A design one square metre over it acquires that application, its timeline, and the consultant work that usually comes with it. That is the largest single step change in a Victorian secondary dwelling budget, and it is triggered by floor area rather than by cost.

Because the exemption depends on lot size, overlays and title conditions, the position for a specific property should be confirmed against Granny flat rules in Victoria and with the council or a registered building surveyor before a design is commissioned.

Why the ranges diverge §

The spread from A$60,000 to A$350,000 is not disagreement about the same thing. Three distinct products are being priced.

The first is the kit route. A supplier states a two-bedroom 60 m² steel-frame lock-up kit from A$67,990 plus GST, with a finished two-bedroom typically landing at A$120,000 to A$180,000 once slab, services and finishes are added — against A$150,000 to A$255,000 for a turnkey two-bedroom from most Melbourne builders^[4]. The gap between those two figures is the labour and coordination the owner takes on.

The second is the base-plus-extras structure. One builder states that many competitors advertise base rates of A$150,000 to A$180,000 and then add A$40,000 to A$80,000 in further items^[7]. That is a builder's characterisation of its competitors and should be read as such — but the pattern it describes is consistent with the difference between the low and high published ranges above, and it is the reason an advertised figure needs its inclusion list attached before it means anything.

The third is conversion versus construction. Converting an existing double garage is put at A$60,000 to A$120,000^[5] and is a different project entirely: the structure and slab already exist, and the work is fit-out, services and compliance rather than building.

Melbourne soil is a real line item §

Footing cost in Victoria is driven by soil classification more than by design. A kit supplier puts slab or pier foundations at A$15,000 to A$30,000 depending on classification, and notes that reactive clay — Class H or E — is common across Melbourne's eastern and northern suburbs and requires deeper footings^[4].

That is a A$15,000 swing determined before any design work begins, and it is the reason a soil test should be commissioned early rather than treated as a formality after a contract is signed. The same source puts plumbing rough-in and fit-off at A$12,000 to A$20,000 for a single bathroom with a kitchen connection, with a second bathroom or ensuite adding A$8,000 to A$12,000, and electrical at A$8,000 to A$15,000^[4].

Energy compliance, and a caution about published figures §

Energy compliance upgrades — double glazing, higher-rated insulation and heat pump hot water — are put at A$8,000 to A$20,000 over a baseline build, with the observation that a small footprint has a high ratio of external wall to floor area and is therefore harder to rate than a full-sized house^[2].

The underlying requirement is worth stating correctly, because several published Victorian cost guides have not kept up with it. Victoria adopted NCC 2022 on 1 May, bringing with it the 7-star thermal requirement and the Whole of Home budget^[8]. Cost guides still describing a 6-star minimum for Victoria are describing a superseded position, and any upgrade allowance calculated against 6 stars will be short. The requirement is set out in Energy efficiency and sustainability in modular homes.

This is the single most common error in the published Victorian material reviewed for this guide, and the reason a builder's energy allowance should be checked against the assessor's certificate rather than accepted from a brochure.

Contingency §

One source recommends a 15 to 20 per cent contingency on a Melbourne project, identifying underground services, site drainage and soil test results as the most common causes of overrun^[5]. That is a higher allowance than the 10 per cent commonly cited elsewhere in Australia, and it is consistent with the soil variability described above.

The Victorian ranges above, including the owner-managed kit route and the garage conversion figure, are also in the cost range finder alongside every other state.

What is not covered here §

No independent Australian survey of completed Victorian secondary dwelling costs has been located for this guide. Council development contributions vary by municipality and are not covered by the sources compiled here. Rental yield and property value uplift figures circulate widely in this market; the published examples are promotional and are not reproduced. Tax treatment of a rented secondary dwelling, and the effect on land tax, are not covered here.

References §