The refurbishment of Leinster House is set to cost in the region of €17 million, an Oireachtas Committee has heard.
Clerk of the Dáil Peter Finnegan told the Public Accounts Committee that the refurbishment of the building on Kildare Street in Dublin, where the Dáil and Seanad are housed, is on course for completion next month.
A major programme of restoration and structural works at the old Georgian building, managed by the Office of Public Works (OPW), began last year.
The OPW has confirmed that the handover of the building back to the Houses of the Oireachtas will take place on 2 August and the works will be completed in time for the return of the houses after the summer recess.
Fine Gael TD Alan Farrell asked had costs been incurred in relation to the move of the Seanad chamber during the restoration.
Mr Finnegan said the commission paid €500,000 to install a lift in the National Museum of Ireland and some other costs relating to securing doors were incurred by the Houses of the Oireachtas.
Sinn Féin TD David Cullinane asked about the overruns with the refurbishment, given that it was reported in 2017 that the projected cost was €8m.
Mr Finnegan said €8m was "quite a rough estimate" and the total project spend comes in at €14.87m.
He said the final cost will come in at about 15% above that, at roughly €17m.
He said one of the reasons for the overrun is a certain amount of the work that was not known in advance and while there was an extensive amount of surveying done before the project, it is impossible to catch everything.
Mr Finnegan said that it was part of the nature of the restoration of historic buildings, that there will be issues that will not be evident at the outset.
Responding to questions from Fianna Fáil TD Shane Cassells, Mr Finnegan said that he believed the project were "very, very good value for money" given the age of the building and the scale of the project.
He said: "One of the outstanding things about this is that there will be a building for the people of Ireland for the future. It is the peoples' parliament ultimately."