The full igloo … a model of the Seidler-designed house. Photo: Courtesy of Penelope Evatt

A BOLD new house designed by Harry Seidler is set to be built in Mosman, more than five years after the acclaimed architect’s death at age 82.

The project has been triggered by the sale of Mosman’s Igloo House (known more formally as the George Williamson House) that Seidler designed in the ’50s.

The heritage-listed modernist building, known for its pair of attention-grabbing arched garages, has been listed for sale by its owners, the Rosemount wine millionaires, Ian and Tanya Oatley. The sale agreement includes DA-approved plans drawn up by Seidler for a new house that the owners were never able to build.

Max Dupain’s photo. Photo: Courtesy of Penelope Evatt

The revamp would include knocking down a dilapidated house on one of the two blocks that make up the property and a ”state-of-the-art luxury revamp” of the Igloo House on the adjacent block at 65 Parriwi Road.

”We won’t be passing the property on to anyone who isn’t going to accept the wonderful plan that Harry Seidler has left,” Mr Oatley said. The Oatleys worked with Seidler for three years before his death in 2006 to design a larger, revamped house to sit across both blocks of the waterfront property.

The plans received council and NSW Heritage Council approval three months ago, by which time the Oatleys’ three children had left home and they had no need for the extra space.

An artist’s impression of the original plans. Photo: Courtesy of Penelope Evatt

Mr Oatley, who owns Hamilton Island with his siblings and father, Bob, a yachtsman who owns the Sydney-to-Hobart winner Wild Oats XI, said he spent two years persuading the previous owner to sell the house.

”I grew up in Mosman and walked and sailed past that house so many times. It’s an indelible mark in my psyche,” he said. ”It features a piece of Australian architecture that was absolutely groundbreaking for its time. I’m looking to pass the baton on to someone else who will respect it for that.”

The Igloo was deemed so strange when it was built in 1951 that it attracted large crowds of people anxious to get a glimpse of the spaceship-like house with its flat-slab concrete construction and glass walls.

It was approved for demolition in the 1990s by Mosman Council because of its perceived lack of architectural merit.

But a public campaign to save it led to an 11th-hour heritage listing in 2002.

The Austrian-born Seidler came to Australia as a refugee from Nazi oppression in the 1930s and earned a reputation as one of the country’s most innovative modernist architects.

He designed more than 180 buildings, including Australia Square, the MLC Centre and the Rose Seidler House in Wahroonga.

Mr Seidler’s widow, Penelope Evatt Seidler,said the new Igloo House was the last major house Seidler designed before he died from a stroke. ”That house has meant a huge amount to us. I get quite shaky even when I think about it now,” she said.

The Dunne Real Estate principal, Sandie Dunne, said interest in the $20 million property had been mainly from Chinese buyers overseas.