The price of dealing with Tauranga City Council's mouldy building saga continues to rise, with officials signing off on more than $500,000 in associated costs so far.

And according to mayor Stuart Crosby, when all is said and done there won't be much change out of $1 million.

Tauranga City Council's HQ on Willow Street.

'It won't be a cheap fix, that's for sure,” he says.

'I know what I have signed off already and it's well over half a million. If I look at what's being done by the contractors, there won't be much change out of a million already.”

Commercial property leases have been signed for part of the Westpac Building in Devonport Road, the former ANZ Building in Spring Street and a building in Durham Street beside the car park to house about 300 displaced staff members.

There workforce required rehousing following announcements on December 15 and 23 that toxic black stachybotrys mould was affecting staff health.

'We signed off for three new office spaces to house a number of staff for at least up to nine months,” says Stuart.

'It could be longer - we really don't know the quantum until we get it fixed.”

Varying degrees of problems can be found in different parts of the building, explains Stuart, and carpets have already been removed in some areas.

'After a re-carpet and a good clean, the staff can come back because the bacteria was in the carpets,” he adds.

'For some of it, people will have to stay away until the building is made watertight, cleaned and re-carpeted. So there are different levels of problems which will require different time frames.”

Council staff camped out in Baycourt will be among the first to move, because the theatre and exhibition space is required for shows.

Mayor Stuart Crosby.

Some of those staff will go straight to Durham Street, where contractors are already setting up the desks.

The Durham Street building beside the carpark was previously leased to the council for the documents digitising contract, while space formerly occupied by a language school on the first floor has also become available.

Council staff are still acquiring information on the state of the buildings and working to get them in a state for staff to return, says Stuart.

A comprehensive report on the buildings' water tightness and earthquake strengthening requirements is expected in March, which is also expected to have better cost estimates.

'Then the council will be in the better position to make some longer term decisions,” says Stuart.

'We are just a commercial building owner and other commercial building owners go through this problems at some point in time. It was only a question of when, not if.”

The council's building manager began gathering information on the possible mould problem in July 2014, says Stuart.

'We knew the problem was starting to manifest to the point that something needed to be done.

'He had already started early information gathering and had some early testing done, but it wasn't until one of our reasonably new young staff members became quite ill that we got the mould tested and some of it was found to be that nasty black stuff (stachybotrus).”

So far the challenge of moving staff and packing them up and moving them again has been achieved without interrupting the council's normal business, says Stuart.

'This council has been reluctant to spend money on itself when we have had other pressures, so it's just that the time is now that something has to be done,” he adds.

'The key in the worst affected areas is to find the leak, and that can be difficult. Water can penetrate in one area and travel a long way, so it's not always easy to identify where water comes in.”