Angela Rayner has threatened legal action against firms who do not speed up fire safety renovations on unsafe tower blocks next year.

The deputy prime minister said it was “unacceptable” that seven years after the Grenfell fire tragedy a single building was still covered in fire-risk cladding.

“My expectation is you will start remediation work on site as soon as possible in 2025,” wrote Rayner, who also heads the housing department, in a letter to housebuilders and suppliers released today.

She added: “My department will take all necessary action to ensure the building is remediated at pace, and that you are held to account if this expectation is not met.

“This could include direct legal action to recover the cost of remediation.”

Last month, a National Audit Office report said the country’s tower block cladding crisis may cost up to £16.6bn and take until 2035 to resolve.

The watchdog estimates between 9,000 to 12,000 buildings over 11 metres may need work.

It added: “Up to 60% of buildings with dangerous cladding have not yet been identified, and remediation for buildings within the government’s portfolio is slow.”

The body also pointed out that the Building Safety Levy is yet to start, which is an agreement for housebuilders and suppliers to pay for much of the remediation.

Rayner in her letter to suppliers said: “I appreciate approval by the building safety regulator is taking longer than expected, and we are working with the regulator to resolve this.”

She added: “We will shortly be setting out our remediation acceleration plan which will outline the additional measures the government will use to ensure homes are made safe as quickly as possible.”

The government’s plan, published today, sets the following deadlines:

• By the end of 2029, all 18m buildings and over with unsafe cladding in a government-funded scheme will have been remediated.
• By the end of 2029, every 11m building and over with unsafe cladding will either have been remediated, have a date for completion, or the landlords will be “liable for severe penalties”

Official housing department data said in June there were 4,374 residential blocks with unsafe cladding, an increase of 38 since April.

Of these, 2,066 buildings, or 47%, have either started or completed remediation works.

One freeholder group welcomed Rayner’s move to speed up remediation, but adds that the real hold up lies with the shortage of building specialists in this area.

Residential Freehold Association director Natalie Chambers says: “We share the government’s objective of making buildings safe as quickly as possible and would urge the government to work with the sector to improve the building safety regime, which is currently causing significant delays to remediation processes.

“The shortage of specialists available to remediate buildings will not be resolved by imposing a deadline nor will it address the various regulatory inconsistencies, funding gaps and delays caused by the building safety regulator.”

The cladding crisis stems from the Grenfell Tower blaze in 2017, which was covered in flammable outer cladding and killed 72 people.

The effect of the tragedy was that leaseholders were prevented with bills running into the thousands to remove dangerous cladding, while lenders would not mortgage these homes for years afterwards until remediation plans were agreed between lenders, government and housebuilders.

The list of developers who have signed the government’s building safety repairs pledge includes Taylor Wimpey, Barratt, Vistry, Crest Nicholson and Bellway.