The High Court has declared that the area of Moore Street in Dublin that should be declared a national monument is wider than that designated by the Minister for Arts and Heritage.
Mr Justice Max Barrett gave his ruling in a case taken by Colm Moore as a nominee of the 1916 Relatives Association.
He has restrained the minister from carrying out any further works to numbers 13-19 Moore Street until she has had an opportunity to consider the judgment and how she intends to proceed.
Mr Moore took the action after numbers 14 to 17 on Moore Street were designated national monuments by the minister.
The buildings are believed to be the last buildings where the leaders of the 1916 Rising gathered prior to their surrender and execution.
Mr Moore and the association claimed the designation should have included lands and buildings of the terrace at numbers 13, 18 and 19 as well as a number of basements and cellars.
Members of the association said it was a great day for the people of Ireland.