The entire roof of the Pacific pool at Chester’s historic City Baths is being renovated after a panel came loose.
Shutting the pool came on top of the almost year-long closure of the larger Atlantic pool at the popular attraction.
The £1.3 million project on the Atlantic pool included tackling corrosion on the steel supports of the roof.
However, last month the smaller Pacific pool was closed to bathers after a roof lining panel came loose.
No one was injured during the incident and the pool was immediately closed until further notice.
A team of engineers was drafted in by council chiefs to carry out safety inspections.
A spokesman for Cheshire West and Chester Council said it was not yet possible to give a definite completion date for the work.
He said: “Both pools will be open before the end of the year.
“The roof of the Pacific pool was examined to see if the damage could be repaired in part.
“However, it was decided it would be far safer and better to restore the whole roof.
“We have already started to renovate the roof on the Pacific pool and work is continuing on the Atlantic pool.
“We’re dealing with a very old building here so we don’t know if anything else is going to crop up while work is being carried out.
“We’re keeping the Swimming Association informed of the situation and will be letting them and the general public know when the baths will be reopening as soon as we know.”
Opened in 1901, the baths replaced Chester’s floating baths at The Groves where Cestrians could bathe in a tank moored for one penny upwards depending on what time of day it was.
The council spokesman added: “A lot of councils up and down the country are closing their historic swimming baths but we are committed to keeping Chester’s open.”