From 30 September 2026, new residential buildings over 18 metres in England must be designed with two staircases. It is one of the most significant changes to high-rise design in years. This article explains what the rule is, why it has come in, and what it means for developers and designers.
What is the second staircase rule?
The rule requires a second, independent staircase in new residential buildings whose top occupied storey is more than 18 metres above ground level. Until now, a single staircase has been permitted in tall residential buildings, relying on a stay-put strategy in which residents remain in their flats during a fire. A second staircase provides an alternative protected escape route and a separate route for firefighters.
Why 18 metres?
The 18 metre threshold aligns with the definition of a higher-risk building under the Building Safety Act, and with other fire safety measures that already use that height. Using one consistent threshold makes the rules easier to apply and removes the confusion of different heights for different requirements.
When does it take effect?
The requirement comes into force on 30 September 2026 as part of the updated Approved Document B. There are transitional provisions: the previous guidance can still apply where building control has been notified before that date and the work has started and is sufficiently progressed, either before 30 September 2026 or within 18 months of it. Schemes in the pipeline should be checked carefully against this.
Other triggers
The amendments also call for a second staircase in certain other situations, for example where flats are not separated from the common staircase by a protected lobby, or where travel distances exceed set limits, broadly 7.5 metres in a single direction or 30 metres where escape is possible in more than one direction. Design teams should read the detail rather than relying on the headline height alone.
What it means for design and cost
A second staircase takes floor space, which affects the number of flats a building can provide and therefore its viability. It changes core layouts, structure and circulation. The developers who manage this best treat it as a fundamental design parameter from the very start, rather than trying to work it in later.
How it fits with sprinklers and suppression
The second staircase rule is part of a layered approach to high-rise safety, not a replacement for other measures. Sprinklers remain required in new residential buildings over 11 metres, and suppression continues to be one of the most effective ways to control a fire at the source. A well-designed high-rise scheme combines protected escape routes, robust compartmentation and a maintained sprinkler system, each supporting the others. Planning your sprinkler design alongside the staircase strategy keeps everything coordinated.
Plan early, get advice
If you have a residential scheme over 18 metres, the time to factor in the second staircase and its interaction with suppression is at concept design. Contact Eversafe for advice on integrating sprinklers into a compliant high-rise design.
Frequently asked questions
When does the second staircase rule start?
It applies to new residential buildings over 18 metres in England from 30 September 2026, with transitional provisions for schemes already in progress.
Does the rule apply to existing buildings?
No. It applies to new building work. Existing buildings are not required to retrofit a second staircase.
Do I still need sprinklers as well?
Yes. Sprinklers are required in new residential buildings over 11 metres and are part of a layered safety approach.