The derelict swimming baths which won the BBC's Restoration programme in 2003 will need an extra £2.5m to be returned it to its former glory, it has emerged.
The building has been derelict for more than a decade
Manchester's Victoria Baths were promised around £3.5m from the Heritage Lottery Fund, Manchester Council, the Restoration Fund, and English Heritage.
Friends of Victoria Baths have re-costed the work and the first estimate falls short of the cash needed.
The group is now looking for funding to get the restoration off the ground.
The complex includes private baths, a laundry, jacuzzi, three swimming pools and the Turkish baths.
An original bid was put forward to renovate the Turkish baths at an estimated cost of £3.5m, leaving the rest of the complex to be renovated if and when funding became available.
But The Heritage Lottery Fund (HLF) now says the Friends of Victoria Baths have to come up with the plans - and funding - to restore the whole building, before any work can be approved.
A price tag of £18m has been put on restoring the entire building, not including the ongoing costs necessary to fund a public swimming facility.
A HLF statement said: "Restoring built heritage always takes a long time.
"The baths would never have been restored in one year.
"From the very beginning, everyone involved has recognised a solution for the whole building was needed and understood that to spend millions on one part of the building without knowing how the rest is going to be restored wouldn't deliver maximum benefit to the lottery players' money.
"There would be a risk that the restored part would not be used much while the rest continued to deteriorate," it continued.
But Gill Wright, of the Friends of Victoria Baths, said: "It's not just about coming up with capital, it's about underwriting it.
"We knew for definite that we couldn't do a swimming pool because there's ongoing revenue needed - and where's that going to come from?
"This project needs a lot of support from a lot of different funders," she said.
The baths won the prize after 282,018 viewers voted for the project to win.
The baths were built for the poor of inner Manchester between 1903 and 1906.
When the Lord Mayor opened the building in September 1906 he described it as a "water palace" of which "every citizen of Manchester was proud".
The council closed the baths in 1993, in the face of much local opposition.