It is a decision his Deakin family might now regret, as it mounts a fight through the ACT Civil and Administrative Tribunal against what it says is an "unfounded and entirely detrimental" ruling that has left them dumbfounded and angry.

Eighteen years after it was first nominated, the Northcote Crescent home has been placed on the heritage register, with all the restrictions that entails.

Michael Bowden, the current owner, has almost finished a 10-year plan of "major renovations, modifications and improvements, including alterations and additions".

The original six-room house now has 12, soon to be 14, rooms, and according to Mr Bowden almost every element of the house has changed in the ensuing six decades.

Mr Bowden would not be interviewed, saying the issue was before the tribunal.

Documents lodged with the ACT Civil and Administrative Tribunal show the family is looking to overturn the decision, which the family members say will severely impact their freedom to develop their home and will decrease its value.

"I greatly resent the intrusion of the ACT Heritage Council into my family's life and the repeated threat of heritage listing," Mr Bowden wrote in the documents.

"The restrictions which would be imposed on me and my family, the financial loss which would be borne by me and my family and the disruption of my family's continued and unfettered enjoyment of our private home ... are entirely unacceptable."

The heritage council included the property on the register in November as an important example of post-war architecture.

"[The home] demonstrates [Seidler's] adoption of Bauhaus design principles and is one of the most significant examples of the early Post-War International Style in a detached residential building in the ACT," the council said in its decision.

Mr Seidler claimed it as one of his favourite designs and in 2006 said of the two detached homes he designed in Canberra, Bowden House was the better example.

However Mr Bowden said, in his submissions to the tribunal, that renovations and additions to the home over 60 years had left it almost unrecognisable.

"The family home which now stands bears little resemblance to the two-bedroom house of the 1950s and has irrevocably deviated from the Bauhaus design in almost every sense," Mr Bowden wrote.

The council referenced the home's cubiform overall shape, the use of large sheets of glass, the use of natural stone and other elements that were typical of the period and of Seidler's designs.

It said the house was important in demonstrating the principal characteristics of modernist architecture.

Heritage council chairman David Flannery said Bowden House met the heritage criteria to a high degree and the council had come to its decision after a robust assessment and would maintain its position.

"The ACT’s 20th century heritage makes an important contribution to our sense of place and identity," Mr Flannery said.

"Our built heritage encompasses many Modernist buildings that contribute to the character of our streetscapes and suburbs."

Mr Bowden said the property had previously been considered for addition to the register in 2000 and had been dismissed. He questioned why the council had now decided to include his home.

But Mr Flannery disputed the claim that the heritage council had already considered and dismissed a listing, saying the council accepted a nomination for the property in 2000 and made a decision in 2018.

The home had been identified as having been on the nomination list for too long, so the council decided to finalise the matter.

Mr Bowden said the heritage council had paid no attention to the effect its decision would have on the family.

Mr Flannery said heritage registration did not mean all change was prohibited.

"[It] does not oblige owners to freeze a place in time or open it to the public as a museum," Mr Flannery said.

"The heritage council recognises that change is often required to ensure heritage homes provide a comfortable and contemporary living standard."

The home was the first commission of Mr Seidler outside of Sydney.

Mr Seidler himself designed an extension several years after the home was built, which Mr Bowden said had compromised the original design.

The council's assessment acknowledged the many changes to the house, but Mr Flannery said they did not diminish the heritage values of the house nor its ability to express Mr Seidler's original design.

The family's challenge to the heritage listing goes to the ACT Civil and Administrative Tribunal later this month.