MLAs voiced concerns that a survey of Northern Ireland's historic buildings that should have taken 11 years was now expected to last 30 years, on 23 May 2012.
The public accounts committee was considering a 2011 Audit Office report entitled "Safeguarding Northern Ireland's Listed Buildings".
The report found that the original work of the Environment Agency's second survey of historic buildings, up to 2007, represented a "Rolls Royce" approach, which "contributed to the survey falling significantly behind schedule".
Committee chairman Paul Maskey of Sinn Fein wanted to know why it was now estimated that the buildings survey would take 30 years.
Permanent secretary of the Department of the Environment (DOE) Leo O'Reilly admitted that, "it has gone on longer than it should have done".
He said there were three main reasons for this.
There was an underestimation of how much work needed to be done, there had been changes of contractual relationships over time, and problems over resource availability.
Mr O'Reilly added that there had been substantial reductions in funding in the period 1999 - 2001.
The UUP's Michael Copeland said it struck him that six years was a long time to review the surveying process.
Mr O'Reilly explained that by 2001 there was a backlog of fieldwork that needed to be processed.
The survey restarted in 2004, he said, and stopped again in 2006 due to a tendering process that resulted in tenders that were deemed too expensive.
Mr Copeland begged the chairman's indulgence, stating that he was a joiner by trade and was keen to see the "early joinery work" in an outbuilding at Prehen House, a property listed in the Audit Office report.
Alex Easton of the DUP wanted to know more about government-owned historic buildings.
Michael Coulter of the NI Environment Agency said the agency believed that government should lead by example.
"We are keen to play our part in that," he added.
Manus Deery, also from the agency, identified seven listed buildings owned by central government and 31 owned by public bodies that were considered to be at risk.