The new rules were confirmed by Housing Secretary Michael Gove on Monday.

Consultations last year had an initial threshold of 30m for second staircases in new schemes which has already been adopted in London and subsequently led to the shelving of a series of planned new residential schemes.

Gove said his tighter rules would provide definitive guidelines for developers and “transitional arrangements” would cover schemes already in the pipeline.

He said the government is “providing much-desired clarity to builders that 18m will be the threshold that we will introduce for new buildings requiring second staircases.”

Gove added: “And of course there will be transitional arrangements in place to make sure that there is no disruption to housing supply.”

The move was welcomed by industry trade bodies.

Eddie Tuttle, Director of Policy, External Affairs and Research at CIOB, said: “The safety of residents and emergency services workers is paramount and can never be understated.

“We have always believed the proposal to mandate secondary staircases for buildings over 18 metres tall to be the best solution as it provides a more comprehensive strategy in ensuring all high-risk buildings have more than one means of a safe entrance and exit.

“Not only does it make exiting buildings in the event of an emergency easier, but it also allows emergency workers to avoid interruption.”