Multi-millionaire financier Mr Dermot Desmond is expected to seek a High Court review of An Bord Pleanála's decision to refuse planning permission for alterations to his house in Dublin's Merrion Square.
Last year, Mr Desmond initiated High Court proceedings against Dublin City Council contesting its right to refuse permission for the alterations he had carried out to house, formerly the home of fashion designer Sybil Connolly.
The council said the works would "cause unacceptable damage to the original fabric of a protected structure of national architectural heritage importance", creating an undesirable precedent that could undermine Dublin's Georgian character.
Dúchas, the Heritage Service, also expressed concern about the alterations, including the use of hardwood wall panelling, marble bathroom floors and marble chimneypieces in the main rooms as well as the removal of original joinery.
Illium Properties Ltd, Mr Desmond's company, had sought permission to retain and complete the installation of a dumb-waiter and electrical riser duct serving all floors of the house, which is a protected structure under the 2000 Planning Act.
But An Bord Pleanála said the alterations to the house, 71 Merrion Square, represented "an unacceptable level of damage to, and removal of, the original fabric" of the Georgian building, which dates from the mid-18th century.
Extensive panelling of an area adjoining the chimneybreast in the main reception rooms to conceal substantial service ducts had resulted in "visual disruption and alterations to the original form, proportion and character of these rooms".
Ruling that the alterations would "materially and adversely affect the character of this protected structure" and would be contrary to this policy, it said they would, therefore, be contrary to the proper planning and development of the area.
Dr Diarmuid Ó Gráda, the planning inspector who had dealt with the case, had recommended that permission should be granted for the alterations given that the house was being restored to residential use as a single dwelling unit.
If Illium Properties Ltd fails to have An Bord Pleanála's ruling overturned in the High Court, Mr Desmond would be required to remove the unauthorised alterations already carried out.