Mr Crosby said the council would have an accurate figure of costs and options by March to remedy the problems.
Part of the old building also needed earthquake strengthening and it could be better to do that work while most staff were working elsewhere.
The entire second floor of the main building and much of the newer buildings centred around the Wharf St side of the complex were now empty, with staff working at Baycourt, at home, or in safe areas such as the debating chamber and adjacent meeting rooms.
Mr Crosby said the council was already heading over a million dollars with what it has had to do in the wake of a staff member falling sick after inhaling toxic mould. He has since recovered and was on holiday.
The public impact has been most felt by the closure of the Tauranga Public Library's non-fiction section.
The upstairs non-fiction section has been sealed off, with staff doing everything they could to make sure people were able to access information.
Library staff were notified of the partial closure at 2pm on Christmas Eve and since then the only non-fiction books the library has been able to lend have been those returned by borrowers.
Books in the sealed-off section were undamaged by mould.
The library's downstairs sale book shelves were now filled with non-fiction books, leaving a small area by the main entrance to display a few fiction sale books.