Floor Space Ratio for Residential Builds in Australia: FSR and Plot Ratio

What it is

Floor Space Ratio (FSR), called plot ratio in some jurisdictions, is the ratio of the gross floor area of all buildings on a site to the site area. An FSR of 0.5:1 on a 600 m2 lot allows 300 m2 of gross floor area. FSR is the second hardest cap on a residential design after height, and it is the one that quietly kills second storey extensions and large family homes on tight lots.

FSR appears in the Standard Instrument Local Environmental Plan (LEP) used by NSW councils. Victoria does not use FSR for most residential zones in the Victoria Planning Provisions, instead capping floor area through site coverage, garden area and ResCode standards. WA and QLD use plot ratio in some local schemes, particularly for higher density residential, and rely on site coverage and setback for low density.

How FSR is set in NSW

In NSW each LEP has clause 4.4 setting FSR, with the actual number shown on the Floor Space Ratio Map. The Standard Instrument LEP template makes the clause uniform, while the map allows lot by lot variation. Typical residential FSR ranges sit around 0.5:1 to 0.75:1 for low density R2 zoned land, and rise to 0.9:1 to 2:1 or higher in medium and high density zones depending on the council.

For example, parts of Woollahra apply 0.5:1 with a sliding scale for smaller lots, and parts of Byron LEP apply 0.5:1 to dwelling houses on residential zoned land. Inner city councils such as Sydney apply higher FSRs reflecting the urban form. Clause 4.6 of the LEP allows a written request for variation of FSR as a development standard, although consent authorities apply increasing scrutiny to variations above 10 per cent.

How gross floor area is calculated

GFA is defined in the Standard Instrument LEP dictionary. It is the sum of the floor area of each floor of a building, measured from the internal face of external walls or the internal face of walls separating it from an adjoining building. It includes habitable rooms in a basement or attic, mezzanines, and habitable parts of an outbuilding such as a granny flat. It excludes lift towers, plant rooms, voids above a floor, carparking to meet the council standard, and balconies and terraces up to a defined area.

The exclusions matter at design stage. A 30 m2 deep void over a void area saves 30 m2 of GFA, which on a 600 m2 lot at 0.5:1 frees up usable internal area. Carparking exclusion only applies if the spaces are required to meet the DCP, so over provision counts against the FSR. Get the GFA take off wrong at concept and the architect carries the rework cost.

FSR and other caps stack

FSR rarely sits alone. Site coverage, height of buildings, setbacks and landscaped area all act together. A lot might have an FSR of 0.6:1 but a 40 per cent site coverage cap that bites first on a single storey design. A two storey on a small lot might be FSR limited even with generous coverage. The order in which the caps bite changes with lot size and building type.

Plot ratio in other states

WA local planning schemes use plot ratio in the R Codes residential design codes. The R Codes set plot ratio for higher density single houses and grouped dwellings, with low density R20 to R40 sites controlled mainly by site area and open space rather than plot ratio. The R Codes operate as a deemed to comply and design principles framework, so variations are possible on merit.

QLD planning schemes occasionally use plot ratio for medium density and apartment development, but low density residential is controlled through site cover, setbacks and Queensland Development Code MP 1.2. Victoria caps floor area indirectly through clause 54 and 55 ResCode standards, including site coverage of 60 per cent under standard A5 and B8 of clause 54, plus minimum garden area under clause 32.

Why builders care about FSR

FSR is the cap that decides whether a project is viable. On a small lot a buyer pays for land area and council allows a fixed slice of it as built form. If FSR is 0.5:1 on a 450 m2 lot, the maximum GFA is 225 m2. A four bedroom home with garage and ensuite struggles to fit that envelope without compromise. Pre purchase due diligence on FSR is the single highest value half hour on any residential site investigation.

For builders working off a designer drawing set, a GFA take off at contract stage protects against late stage compliance failure. If the design exceeds FSR, the consent authority will require redesign, which delays approval, lock in dates and sometimes the deposit release. Cross check the GFA shown on the architect plans against the LEP definition before signing the build contract.