Short answer
In Victoria a small second dwelling is a self-contained home of 60 square metres or less on the same lot as an existing house. In most residential and rural zones it does not need a planning permit, as long as the lot has no flooding, environmental or other special planning controls. It always needs a building permit.
Since December 2023, Victoria has had a simpler path for building a second small home on a lot that already has a house. The planning rules call it a small second dwelling. Most people call it a granny flat.
What counts as a small second dwelling
To qualify, the dwelling must:
- have a floor area of 60 square metres or less
- be on the same lot as an existing home
- be self-contained, with its own kitchen, bathroom, toilet and laundry
- not be connected to reticulated natural gas
- have an access path from the street
It does not need its own car parking space.
The 60 square metres is measured generously. The Building and Plumbing Commission counts floor area from the outside of the external walls and includes all roofed areas, so a roofed verandah or deck counts towards the limit.
When you need a planning permit
In most residential and rural zones, a small second dwelling does not need a planning permit, as long as the lot has no flooding, environmental or other special planning controls.
You will need a planning permit if:
- your lot is under 300 square metres in a residential zone, other than the Low Density Residential Zone
- an overlay or other special control on your lot requires one
Zones and overlays vary from street to street. Your council can tell you which apply to your lot before you spend money on design.
You always need a building permit
A building permit is required for every small second dwelling, whether or not it needs a planning permit. It is issued by a registered building surveyor, who can be a private surveyor or your council's.
The siting and design standards sit in Clause 54 of the planning scheme and Part 5 of the Building Regulations 2018. They cover matters such as setbacks from boundaries and the garden area left on the lot.
Who can live in it
Anyone. A small second dwelling can be used by family or leased to a tenant, and residential tenancy laws apply. It cannot be subdivided from the main house or sold separately.
If you plan to use it for short stays
The rules above are about building the dwelling. Offering it as short-stay accommodation raises separate questions. Your council may have local rules, and Victoria has a short stay levy administered by the State Revenue Office. Check both before you rely on short-stay income.
Where design fits
Sixty square metres has to work hard. With roofed outdoor areas counted in the total, the layout decides whether the home feels generous or cramped.
We work at the concept stage: the layout, form and materials of the home, shown in photoreal 3D so you can judge it before you pay for documentation. A registered building designer, architect or builder then prepares the building permit drawings.
If you are considering one of our pre-designed homes as a second dwelling, ask for its floor area when you register your interest. For a design made for your block, see custom home design.
Sources
Diego Benavides leads Diego Benavides Design, a Melbourne studio for architectural visualisation and home design. This guide is general information, last checked on 7 October 2026. Rules change and every lot is different. Confirm what applies to yours with your council or a registered building surveyor.