Government cannot say how much works to Leinster House will cost despite committing to a significant refurbishment of the building,
.The Seanad is to move to the National Museum from September as part of the renovation, restoration and structural works which will continue until the end of 2018.
The project is expected to run into millions of euro, however, the OPW cannot give even a ballpark figure for the total spend.
John Cahill of the OPW said a full figure has yet to be reached.
"Since 2007 we have been opening every floor, every part of the building that we could get into," he said adding that parts of the building "still have to be examined".
"The actual repair is something that we don't have a full figure on or a final figure on.
"What we would be saying is we have already under European tendering pre-qualified some very good contractors.
"In terms of the money that is needed it is mainly a skill-based, it is craftsmen, and that's why the full estimation of the cost is not something we can make up at the moment."
Asked if there is the total budget, Mr Cahill said: "We have to do the job."
He added: "We have already said that in going out for tender that the construction cost, net of everything else, will be in the order of at least €8m because we have to indicate to Europe the scale of what's there, but that's only indicative of the type of figure that you are talking about.
"You are talking about all those skills, all that time for plaster restoration in the interior, all those elements in which we haven't had a chance to lift the floors and get into so that will add to the cost."