What is site coverage? Limits and private open space rules in Australia

Site coverage is the proportion of a lot's area covered by buildings, expressed as a percentage. In New South Wales, the complying-development rules define it as the proportion of a site area covered by buildings¹. The Victorian Building Regulations 2018 define it as the part of the allotment covered by buildings, expressed as a percentage of the allotment's area². Queensland's state code does not define the term and instead caps the area covered by all buildings and structures roofed with impervious materials³.

What counts towards site coverage varies between different rules, particularly for eaves, pergolas and unenclosed structures. Victoria disregards up to 600 mm of eaves, fascia and gutters, and disregards unroofed pools, spas, terraces, patios, decks and pergolas². The Blacktown Growth Centre Precincts DCP counts the dwelling and other structures on the lot, including a carport, garage or shed, but excludes unenclosed balconies, verandahs, porches and alfresco areas⁴.

Estate documents set their own rules for what is included. Flagstone's guidelines count everything under a fully impermeable roof, including a covered alfresco, porch or shed, and exclude open pergolas⁵. North Harbour excludes unenclosed patios, verandas and balconies and includes studios and outbuildings⁶, while Harmony measures the site covered by buildings but excludes eaves⁷.

Private open space requirements vary by state and approval path. Minimums range from 16 m² in parts of New South Wales and Queensland to the lesser of 80 m² or 20 per cent of the lot in Victoria on the building-permit path. Among the estate guidelines reviewed, the minimum falls as low as 10 m².

In Victoria, the required private open space must include at least 25 m² at the side or rear of the house, with a minimum width of 3 m and convenient access from a habitable room other than a bedroom².

The Victorian regulations count unroofed land, as well as a deck, terrace, patio, balcony, pergola, verandah, gazebo, swimming pool or spa, as private open space.

Where a planning permit is needed in Victoria, different private open space requirements apply. Private open space must be at least 20 per cent of the lot and not less than 25 m², with direct access from a living area, dining area or kitchen. At least 25 m² must be secluded private open space with a minimum dimension of 3 m⁸. On a 450 m² lot, that is 90 m², compared with 80 m² on the building-permit path.

In New South Wales, the complying-development rules require principal private open space of 16 m² on a lot 6 to 10 m wide at the building line and 24 m² on a wider lot¹. The space must measure at least 3 m by 3 m and have a slope no steeper than 1:50. It must be directly accessible from, and next to, a habitable room other than a bedroom.

In Queensland, lots under 450 m² require an outdoor living area of at least 16 m², with no dimension under 4 m, access from a living area and a slope of no more than 1 in 10⁹. The state code does not set an outdoor living minimum for lots of 450 m² or more, so other planning or estate rules may apply.

Estates and councils set their own figures. North Harbour requires a single area of 25 m² with a minimum dimension of 5 m⁶, The Surrounds plan of development requires 25 m² with a minimum dimension of 4 m for a dwelling with ground-level living¹², and Flagstone requires 10 m² with a minimum dimension of 2.4 m, directly accessible from a living space⁵. The Blacktown Growth Centre Precincts DCP requires 20 m² of principal private open space for lots 9 to 15 m wide and 24 m² for wider lots, with a minimum dimension of 4 m⁴.

On a 450 m² lot, a 50 per cent limit allows 225 m² of roofed area³, a 55 per cent limit allows 247.5 m²¹² and a 60 per cent limit allows 270 m²². These figures illustrate the Queensland 50 per cent limit, The Surrounds' 55 per cent band and Victoria's 60 per cent limit.

In New South Wales, the complying-development rules use gross floor area rather than site coverage. On the same 450 m² lot, the maximum gross floor area is 262.5 m², calculated as 25 per cent of the lot area plus 150 m². The lot also requires 67.5 m² of landscaped area, equal to 15 per cent of the lot¹⁴.

Among the 3,654 designs in BuildStreet's catalogue that included a published house area at the 10 July 2026 snapshot, the median house area is 255.9 m²¹⁵. If that area is used as a proxy for the roofed area of a single-storey house, it would cover about 56.9 per cent of a 450 m² lot. That is above the 50 and 55 per cent limits and below the 60 per cent limit.

Using the same illustrative calculation, 255.9 m² would require a lot of about 512 m² under a 50 per cent site coverage limit and about 427 m² under a 60 per cent limit.

This is an illustrative comparison, not a measurement of each design's actual roofed area. Builders' advertised areas are total floor areas, and whether they include the garage, porch or alfresco varies by builder. A design's actual roofed area can therefore differ from its advertised floor area.

A two-storey design spreads the same floor area over two levels, so if the ground-floor footprint were about 128 m², it would cover around 28.4 per cent of a 450 m² lot.

The site coverage figure that applies to a block can come from up to three sets of rules:

• State rules. In Victoria, this includes the Building Regulations 2018. In Queensland, the applicable state siting rules depend on the lot size. In New South Wales, the complying-development rules use floor-area and landscaped-area limits rather than a site coverage percentage.
• Council or development-area rules. A council plan can set a site coverage figure, as the Blacktown Growth Centre Precincts DCP does for development applications. Some Queensland development areas can also have their own siting requirements.
• Estate documents. A plan of development, design guidelines or a lot-specific building envelope can set additional requirements for the block. Among the Queensland estates reviewed, these documents set the site coverage band for individual lots.

BuildStreet reads the coverage rule from these sources and tests it against a design's ground-floor footprint where the builder publishes one. Where only a total floor area is published, a single-storey design's floor area is used as a clearly labelled proxy. For a two-storey design without a published ground-floor footprint, site coverage is reported as not checked rather than estimated.