A Sydney court ruling could make apartments larger and even less affordable in what is already one of the world's most expensive housing markets.

A new court ruling in NSW could compel property developers to increase the scale of new apartments in the state following the clarification of minimum size requirements.

In the ruling issued on April 9 by the NSW Land and Environment Court concerning Botany City Council v Botany Developments Pty Ltd (No 2), Justice Sheehan said that the “rules of thumb” of the Residential Flat Design Code that are generally employed were not the appropriate guideline for minimum apartment sizes.

According to the rules of thumb the recommended size for a single bedroom apartment is 50 square metres, 70 square metres for a two bedroom apartment and 95 metres for a three bedroom apartment.

Justice Sheehan instead pointed to an adjacent table in the Residential Flat Design Code as providing the correct minimum dimensions for apartments in the state.

The code’s table diverges significantly from the rules of thumb, advocating at least 58 square meres for a one bedroom apartment, 91 square metres for a two bedroom apartment, as well as a sizeable 53 additional square metres for three bedroom apartments.

NSW first introduced minimum apartment sizes in 2002 with a set of design rules contained by State Environmental Planning Policy No. 65.

The ruling was made in response to a dispute over the size of a set of 158 units in a 3 to 6 storey building between Botany City Council and Botany Developments Ltd Ltd.

The development control plan drafted by Botany City Council mandated even larger single bedroom apartments, with a minimum size of 75 square metres.

The decision could have far-reaching ramifications for Sydney’s property sector, potentially increasing the average size and cost of apartments within a market that’s already considered by many to be heavily overpriced.

It’s impact could be particularly significant for the lower end of the market, making apartments more expensive for those Sydney-siders who experience the greatest difficulty in securing affordable accommodation.

The Urban Taskforce wants the state government to intervene against councils pushing for larger apartments to the detriment of affordability for local residents.

“Sydney is already one of the most expensive cities in the world for housing and the NSW Government must do all it can to minimize costs,” said Urban Taskforce CEO Chris Johson. “One way do to this is to ensure that all councils conform to the same minimum apartment sizes.”

The Taskforce has called in particular for the new Minister for Planning Rob Stokes to settle the matter by providing greater clarification on the state’s confusing welter of size requirements.

“The Urban Taskforce believes the new Minister for Planning has an opportunity to begin sorting out the state’s complex planning system by clarifying the legal interpretation of minimum apartment sizes before Sydney’s 41 separate councils start setting their own standards now that the rules seem to have been changed by the court.”