Developer Theo Onisforou lists his grand Elizabeth Bay terrace plans for $15 million

An Elizabeth Bay house that last traded three years ago for $6.8 million returns to the market next week for $15 million, thanks to one significant improvement to its value since then.

The 556-square-metre property now comes with hard-won DA approval for two separate four-storey terraces on site that agents say would be worth between $15 million and $20 million each once completed.

While the specs to the grand design are the brainchild of acclaimed architect Tony Chenchow, the deep pockets behind it all is property developer Theo Onisforou.

The prominent businessman and Southern Highlands cattle farmer bought the house on dress circle Billyard Avenue in 2016 for $6.8 million from socialite Erin Kildaire.

Any plans for the site would need to be impressive given it is one of only 10 free-standing houses on the harbourside street. It came with contributing heritage significance as the last of three in a row built in 1916 still standing.

Among the DA’s detractors is Andrew Woodhouse, president and founder of the Potts Point and Kings Cross Heritage Conservation and Residents Society, who last year described it to The Sydney Morning Herald as “out of character with its surroundings”.

Despite more than 25 objections to the proposal, Sydney City Council was ultimately swayed by the DA’s design excellence and the fact the original neighbouring houses were long ago redeveloped into apartments, voting unanimously in favour of the DA in August last year.

“I’ve been told not to wait to the last minute to proceed with the redevelopment because it’s unlikely such a DA would pass council again,” said Mr Onisforou.

Those four-storey terraces feature a fluted facade set above the original sandstone wall and basement garaging with a grand entry foyer and triple-height ceiling to the skylit living area.

An internal living space of 500 square metres each would include four bedrooms, a gymnasium, cellar, home cinema and formal and informal living areas, making them arguably among the largest terraces in Australia.

“These will be the largest terraces built since Victorian terraces originally graced Sydney’s streetscape,” Mr Onisforou said.

And given a resale value of between $15 million and $20 million each, they would also be the most expensive.

Australia’s terrace record was reset late last year in nearby Potts Point when a grand Victorian Italianate residence on Challis Avenue was sold by father and son property investors Roy and Anthony Medich for $14,699,167 to Rupert Murdoch’s eldest daughter Prue MacLeod and her husband Alasdair.

“The combination of position and a masterclass of architecture makes this a really exciting development for the area,” said Jason Boon, of Richardson & Wrench Elizabeth, who has listed the property with Shannan Whitney, of Bresic Whitney.