The London Borough of Hackney has said it will take legal action against the builder of a housing block that the council is evacuating due to defects.
Building firm Willmott Partnership Homes has strongly disputed the council’s case.
Tenants at Bridport House have been warned they must move while work is completed to replace incorrect “potentially combustible insulation” installed when the flats were built in 2011, the council said.
The 41 families affected will be offered another temporary or permanent home within Hackney.
A Hackney statement said investigations had revealed a series of other serious construction defects, including missing smoke and fire barriers and flawed brickwork, balconies and windows.
The council said advice from London Fire Brigade, the Health and Safety Executive and independent experts was that it would be unsafe for residents to remain while work to remove and replace the insulation takes place. Works could take around two years to complete,
Hackney said the insulation concerned is not the type used on Grenfell Tower.
Elected mayor Philip Glanville said: “Moving residents from homes we all hoped would be new and permanent is not an easy decision, but our first priority is their safety, and we have decided that at Bridport House, doing this work while the building remains occupied would create an unacceptable risk.
“We will be taking legal action to hold those responsible for these failures to account. We also should have done a better job.”
Willmott Partnership Homes said in a statement: “Willmott Partnership Homes is disappointed at the way the problems at Bridport House have been portrayed by Hackney Council.
“This is an extremely complicated matter, significantly exacerbated by various aspects of the Building Regulations recently being reinterpreted following the Grenfell tragedy.
“For example, the insulation the council refers to was widely accepted as complying with Building Regulations at the time it was installed, and indeed was specifically approved as being compliant by the council’s building control team.”
The builder said the cross laminated timber frame structure and the insulation were both detailed within the council's tender specification “upon which the building contract was entirely based”.
It said the council’s threat of legal action meant it could not make a fuller response but added: “We too want to say how sorry we are that matters have turned out in this way, and of course for the concern this will have caused to the residents at Bridport House.”