A former swimming pool building that sank into such “poor condition” that it was added to a heritage-at-risk register will be transformed into offices, a cafe and community space.

The pool hall at Haggerston Baths, built in 1904, will be converted into an area for private and community events, along with a public gym. There will also be work space and conference facilities.

When the baths opened many homes did not have their own bath.

The venue had 60 baths for people to wash alongside a swimming pool.

The council-owned baths closed down in 2000 and campaigners fought to retain the swimming pool.

The council discussed options with a developer but was unable to come up with an option giving the public enough access to the baths.

Both a 1950s extension that was used as a public laundry and part of the 1904 development will be knocked down and replaced with extensions up to six storeys tall.

Hackney Council selected developer Castleforge after a public consultation and competitive bidding process in 2017.

Historic England said the building is in a “state of disrepair”. It costs the Town Hall £100,000 a year for security and maintenance of the empty building.

The developers said: “Our intention is to redevelop this historically significant local landmark to make it once again an important centre of activity and a vibrant part of Haggerston’s future.”

Sixteen objectors told the council’s planning department that the six-storey extension would harm their enjoyment of the historic baths building and they would suffer from a loss of sunlight.

But the council’s planning officer Nick Bovaird said of the loss of sunlight: “We find it acceptable and not untypical in an inner London location.”

He added that because the building is in a poor condition, it is possible that if nothing was done there would not be a listed building to enjoy.

The developers needed the sixth floor to make the plan viable as they could charge premium rent there, the committee was told.

Oliver Vickerage, the scheme’s development manager, said the public would be able to use a community workshop space in the basement and the ground floor of the pool and deck area with “free access”.

The scheme was unanimously approved.