Neither Grimshaw nor the council will commit itself to a handover date. A council spokesperson said: "We are waiting for the architect's report explaining why it is not signing off practical completion."
Thermae, a Dutch company appointed by the council to operate the spa, also refused to announce an opening date. A spokesperson said: "We will need two weeks after handover to install final fixtures and installations."
The project will reinstate the only working natural spa in the UK. Its centrepiece is a modern open-air, rooftop pool (shown above). Beneath it five grade I-listed buildings lying 100 m from the original Roman baths will be restored, with Donald Insall Associates as architect.
The building contract includes penalties of £12,000 a week for late completion, although council leader Paul Crossley has said the real cost to the council is £15,000 a week.
The late running of the scheme led to a war of words between the project team during the spring.
Mowlem regional director Chris Pape blamed the late completion on lack of detailed specification by the architect and poor project management by the client.
The council's project director, Chris Cavanagh, rejected these claims. He said that he had been advised by Grimshaw that the time extensions claimed by Mowlem had not been substantiated.
A concert in Bath's Royal Victoria Park starring Luciano Pavarotti that is scheduled for next week to coincide with the spa's original opening date will go ahead as planned.