Deadly asbestos has been discovered in council offices during a £1.9m revamp.
It means next month's full council and planning meetings will have to take place in a former social club instead of the council chamber.
The asbestos was discovered by workers ripping out old windows on the third floor of Swale House in East Street, Sittingbourne.
The meetings will now be moved to the Sapling Room at The Appleyard in the nearby Avenue of Remembrance.
Cllr Mike Whiting (Con, Teynham and Lynsted) said: "We know the dangers posed by asbestos. I would have expected the council to have ensured all necessary checks were made before agreeing a price and awarding a contract.
"However, it seems the asbestos found in these windows has come as surprise."
He was planning to raise the matter at Swale council’s property committee meeting this evening (Monday). (Sept 26)
He said: "I will be asking whether this potentially highly dangerous material showed up on previous surveys and, if not, why not?
"I’ll also be asking what additional costs result from the additional work and whether any additional costs will ultimately fall on the hard-pressed ratepayers of Swale?”
A council spokesman said: “Installers began work to install double glazing at Swale House and found what they thought might be asbestos under window frames.
“This has now been confirmed through testing and they are working with their licensed asbestos contractor to establish the extent of the problem, so it can then be removed safely.
“Prior to the works, sample windows were removed to check for asbestos and nothing was found. The asbestos is only present within the packing at the sides or underneath some of the window frames, though not all of them, and does not yet appear to be in any obvious pattern."
He added: “The phased works are only affecting the third floor which is where the council chamber and larger meeting rooms are located.
"As a result, we are working on contingency plans for venues for the October full council and planning committee. Other meetings with smaller memberships can continue to be accommodated at Swale House.”
It is understood it will take three weeks to remove the asbestos.
Councillors agreed to spend £1.9m on revamping the 50-year-old offices in March after abandoning plans to sell them and build a new civic centre.
Contractors are installing double-glazing, repairing and insulating the roof and upgrading all lighting to LEDs. It is anticipated the works could help reduce the council’s carbon footprint by 70 tonnes a year.
The decision to axe plans for a new centre was made in 2020 when a coalition of independents, Labour, Lib-Dems and Greens took over from the Conservatives and ended the Spirit of Sittingbourne venture to regenerate the town centre.
A new civic centre was part of the second phase.
Cllr Monique Bonney, then cabinet member for economy and property, said in March: “Swale House has had very little capital invested in it over the decades. Anyone who has visited it can see the building is tired and well past its best.
“The old, draughty, single-glazed windows are more than 40 years old and desperately need replacing. Issues with the roof need addressing urgently and we need better insulation and lighting to lower the amount of energy we are using to heat and light the building."
She said the improvements would take into account that more officers were able to work from home and would free up 20,000 square feet to rent to private companies to generate income for the council.
Cllr Bonney, who was trapped in one of the building's lifts after a council meeting in December, 2017, added: "Once the roof has been repaired, we can look at the possibility of installing solar panels and with better insulation we can start to look at more efficient heating systems."
Money for the revamp is being borrowed at a cost of £38,000 a year. It is estimated the improvements will save the council £16,800 a year.
Cllr Bonney said: "The council would only need to let a small amount of space to recoup the remaining interest cost."
The second-floor conference room which has been used in the meantime is not big enough for all members, officers and public for bigger meetings.