Up to 60% of buildings with dangerous cladding have not yet been identified seven years on from the Grenfell Tower fire, according to the National Audit Office (NAO).

A new report from the NAO found there has been a ‘substantial increase’ in remediation activity since 2020 with 4,771 buildings brought under the Government’s remediation scheme.

However, the audit office warned it was ‘taking longer than expected’ to identify affected buildings and added ‘some may never be identified.’

According to the NAO’s report, there are a potential 7,200 buildings or more – up to 60% – that have not been identified. It warned the Government might miss its own cladding removal completion date of 2035.

The building safety minister Alex Norris acknowledged that the pace of remediation has been ‘unacceptably slow’,

The auditors’ report also estimates it could cost between £12.6bn and £22.4bn, with a best estimate of £16.6bn, to complete remediation work.

Government funding for this work is capped at £5.1bn and developers are expected to cover £3.4bn through a levy.

Chancellor Rachel Reeves announced £1bn in last week’s budget to accelerate the removal of dangerous cladding.

The NAO also found that in 2023-24 around £500,000 was lost from the Building Safety Fund through a fraudulent claim by one applicant.

Gareth Davies, head of the NAO, commented: ‘Seven years on from the Grenfell Tower fire, there has been progress, but considerable uncertainty remains regarding the number of buildings needing remediation, costs, timelines and recouping public spending.’

Cllr Adam Hug, the Local Government Association (LGA) spokesperson on building safety, said councils are determined to ensure residents are safe but face ‘significant barriers’ in accessing funding.