The Office of Public Works (OPW) is to appear before the Oireachtas finance committee today to answer questions about the €336,000 bike shed.
The glass-covered shelter has been the subject of criticism and ridicule over its high cost.
New figures have revealed the cost of granite flagstones came to around €45,000, while thick glass panels were also used.
Surveying and architectural fees amounted to €11,000, with a similar sum for “outer work” in prepping the site and the side of the National Gallery.
Today, politicians will interrogate the vague terms used in a leaked outline of the OPW’s cost breakdown, which includes €30,000 for “dry work” and more than €23,000 for what is described as “day work”, which thought to relate to the actual construction.
There was also Vat on the construction costs, which totalled more than €38,000, which the State indirectly recouped via payment to Revenue.
The Houses of the Oireachtas Commission has been told the shelter was delayed by challenges caused by buried cables and a direction to stop work around the election of new Taoiseach Simon Harris earlier this year.
Warnings are now being sounded that any attempt to restrain the spending power of the OPW could result in far slower project delivery.
Sources said any escalation to higher-ups could cause delays in completions.Sinn Féin leader Mary Lou McDonald raised the issue in the Dáil yesterday, saying the Government had “presided over the construction of what I imagine has to be most expensive bicycle shed in the world”.
“Five weeks on, we still have no answer as to how all of this happened,” she said.
“It seems to me that the approach of the members of the Government to this matter is the same as their approach to the children’s hospital – they act as commentators. They seem to take no responsibility whatsoever.”
Public Expenditure Minister Paschal Donohoe said: “Of course I accept that the spending of so much money on a bike shed has caused great anger among the public.
“It was not a decision that I made, but I am responsible for the use of the country’s money.”
He added: “I understand that the Office of Public Works recently engaged with the Houses of the Oireachtas Commission. I believe a report from it will be forthcoming on the subject and will lay out what happened and the recommendations to avoid this happening again.”
The number of bikes parked at the new shelter has never exceeded 10 a day over the last three months, it was previously revealed.