The £35 million refurbishment of Birmingham Town Hall has hit fresh financial difficulties.
City council officials have ordered "vigorous" cost control measures after a £1 million contingency fund to deal with unexpected problems arising from restoration work was all but swallowed up in under a year.
Midway through a 104-week construction period the council has been faced with decaying roof timbers, difficulty in installing double glazing without damaging acoustics, the discovery of asbestos and flooding of the basement.
Rita McLean, acting assistant director of museums and heritage, insisted construction work was going well and the town hall would re-open as planned in October 2007.
However, unexpected difficulties, including high tenders for plasterwork repairs, led to several demands on the contingency fund.
Ms McLean told a scrutiny committee: "Strenuous efforts are being made to protect the remaining contingency.
"At this stage, any savings through further value engineering would be more than outweighed by the cost of achieving them.
"Emphasis is therefore placed on vigorous cost control and resisting pressures for unbudgeted enhancements to the scheme."
John Alden, cabinet member for leisure, sport and culture, said he was determined the contract for refurbishing the town hall would not go over budget.
However, he added: "We have got to do the job properly. The contractors must be properly paid for what they need to do if any further unforeseen pressures arise."
Coun Alden (Con Harborne) admitted he cut the contingency budget in half before building work began in order to reduce the overall cost of the project.
"I thought it would make everyone involved be more careful about what was going on," he said.
The council is looking at ways of raising additional money including extending the contract for advertising banners on the side of the town hall, which has so far produced almost £800,000. The planning committee is expected this week to extend temporary permission for the banners until December 31.
There are also fears about the long-term financial stability of the town hall when it finally reopens. The restored building will be managed by Symphony Hall, although a business case is yet to be agreed by the council cabinet.
Ms McLean said examination of an outline business case highlighted the scope for further savings in box office costs.