Housing data · Australia · 2026

Granny flats in Australia: data, rules, costs and official gaps

Granny flats are allowed in every Australian state and territory, but the data is fragmented across industry estimates, planning approvals, building permits and state rules. The clearest available built estimates come from the Housing Industry Association, which estimated that New South Wales built 4,483 granny flats in 2022, down from 5,914 in 2017.

No official source publishes a national count of how many granny flats are built in Australia each year. Because of that, available figures need to be read carefully. An approval is not the same as a completed dwelling, and a state estimate is not the same as a national total.

Every state and territory allows granny flats or equivalent secondary dwellings, although the official names, size limits, approval pathways and rental rules vary. There is also no official national benchmark for the average cost of building a granny flat.

SECTION 01

How many granny flats are built in Australia?

New South Wales has the clearest available granny flat build estimate, with HIA Economics estimating 4,483 builds in 2022. That was down from 5,914 in 2017, a fall of around 24%. The same source estimated that Victoria built 24 granny flats and South Australia built 48 in 2022.

These figures are industry estimates, not official counts. No official source publishes a national count of granny flats built in Australia each year, and the available built estimates cover only three states. They draw on builder survey data and planning sources, and should be read as indicative. The Victorian figure should be treated with particular caution because the sample is very small.

Even in New South Wales, granny flats represent a small share of total housing activity. HIA estimated granny flats accounted for 8.1% of dwelling approvals in NSW, compared with 1.1% in South Australia and 0.4% in Victoria. No comparable built-count estimate has been identified for Queensland, Western Australia, Tasmania, the ACT or the Northern Territory.

New South Wales also has a more recent approval signal, although it is not a built-count figure. The NSW Planning Portal recorded more than 160 development applications and more than 200 complying development certificates each month for secondary dwellings in October and November 2023. Annualised, that equates to about 4,320 approvals a year, but the figure is based on only two months of data and does not show how many granny flats were completed.

Even in the available HIA estimates, granny flats account for a small share of total housing activity. Nationally, 16,710 dwellings were approved in April 2026 alone, and 43,536 were completed in the December quarter of 2025, both seasonally adjusted.

Source: HIA Economics, March 2024. Shares are industry estimates as a percentage of total dwelling approvals.

SECTION 02

Why is there no national granny flat count in Australia?

National dwelling statistics record only broad categories such as houses and other residential dwellings. Granny flats are not published as a separate national series, and no official dataset follows a granny flat from application through to completion.

Each step in the process sits in a different system and measures something different:

• an approval is permission to build
• a building permit confirms work can start
• a completion is a finished dwelling

Terminology adds another layer of complexity. Each jurisdiction uses a different official name for the same type of dwelling, so figures rarely line up between states:

• secondary dwelling: NSW and Queensland
• small second home: Victoria
• ancillary dwelling: WA
• ancillary accommodation: SA
• secondary residence: Tasmania and the ACT
• independent unit: Northern Territory

A 2021 building subclass, "detached secondary dwellings", recognises the detached version of this dwelling type within the national classification system. However, it does not create a published national count of granny flats, and it does not cover every possible layout, such as dwellings built inside or attached to the main home.

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What are the granny flat rules by state and territory?

All eight states and territories allow granny flats or equivalent secondary dwellings, but they use different names, size limits and approval pathways. Most jurisdictions cap floor area at 60 to 90 square metres where a cap applies, while Queensland does not have one statewide maximum. Draft or scheduled changes are marked separately because they are not the current law.

Two points apply broadly across the country: a building permit is generally still required, even where a planning permit is not, and a granny flat usually remains on the same title as the main home.

Source: State and territory planning sources, 2024 to 2026, compiled from official government pages and legislation. Queensland's proposed 80 to 100 m² size range and Tasmania's proposed 90 m² cap are draft changes, not current law. Local zoning, overlays and building requirements may still affect approval pathways.

SECTION 04

Granny flat size limits by state and territory

Most jurisdictions cap granny flats at 60 or 70 square metres, although the ACT allows up to 90 m² and Queensland has no statewide maximum floor-area cap. Size limits have also changed in some states since 2022.

South Australia increased its ancillary accommodation cap from 60 m² to 70 m² in November 2024. Tasmania is consulting on a draft change that would lift its secondary residence cap from 60 m² to 90 m². The ACT's missing-middle housing reforms are scheduled to begin on 1 July 2026, including changes to secondary residence requirements.

SECTION 05

How much does a granny flat cost in Australia?

Granny flat costs vary by site, design, services, approval requirements and builder pricing. Australia does not have an official national average cost to build a granny flat, and no government source publishes a national cost-per-square-metre benchmark or annual granny flat cost series.

The closest official data point is the ABS approval value, but this is not a consumer build price. ABS approval value estimates the value of building work at completion, based on approval documents. It excludes land, demolition and landscaping, includes site preparation, and may differ from the final amount paid by the owner.

The final cost of a granny flat varies depending on a range of factors beyond the base build:

• site conditions, including slope, access and any rock
• services connections (water, sewer, electricity)
• professional fees and approval costs
• bushfire, flood or heritage overlays

Two granny flats with the same floor area can have different total costs once site conditions, services and approval requirements are included.

SECTION 06

How granny flat rules changed in Australia from 2021 to 2026

Between 2021 and 2026, granny flat rules changed across several states and territories. Eight of the developments below are already in force, while two are scheduled, draft or not yet commenced. Most changes happened at state level, with jurisdictions generally easing tenancy rules first and lifting size caps later. Federal changes were narrower, covering building classification and a capital gains tax exemption.

Source: ABS; Australian Government Treasury; and state and territory planning authorities, 2021 to 2026.

SECTION 07

Frequently asked questions