From the 30th September 2026, every new residential building in England over 18 metres must be designed with a second staircase, not one. That’s two weeks away.
What’s Changing From 30th September 2026?
The rule comes from an update to Approved Document B, the government’s fire safety guidance for building regulations.
- Applies to new residential buildings over 18 metres in England
- Requires two staircases to be included instead of one
- Doesn’t apply retrospectively to existing buildings
- Projects that already have building control approval and are underway are generally unaffected, under transitional arrangements set out in the guidance itself.
Why Was 18 Metres Chosen?
The government’s original 2022 consultation proposed a 30-metre threshold. The final figure was reduced to 18 metres and was set to align with the definition of a “higher-risk building” under the Building Safety Act, so the fire safety rules and building safety rules now use the same height, rather than two different ones.
What Does A Second Staircase Mean For Fire Doors and Compartmentation?
A second staircase isn’t an isolated change. Adding one reshapes the layout around it, creating new corridors, new protected lobbies, new risers and in some cases, new evacuation lifts.
Each of those is a new compartmentation line. Each one needs a correctly specified and installed fire door or fire stopping detail to actually work.
This is where the practical risk sits. The staircase gets designed in the early stages and signed off on paper, but the fire doors and fire stopping around it often get treated as a late-stage detail, specified under time pressure once the rest of the building is already taking shape.
What Should Architects, Contractors and Housing Providers Be Doing Now?
If you’re an architect, contractor, housing association or local authority working on a residential scheme over 18 metres, the staircase itself is only part of the job. The corridors, lobbies and risers it creates need fire doors and fire stopping designed in from the same early stage, not added on once the layout is fixed.
If you’re an architect, contractor, housing association or local authority working on a residential scheme over 18 metres, the staircase itself is only part of the job. The corridors, lobbies and risers it creates need fire doors and fire stopping designed in from the same early stage, not added on once the layout is fixed.
Consulting with fire door specialists such as LFS early makes that easier to get right, since the people manufacturing and certifying the doors can also advise on the compartmentation around them, rather than fire door supply coming in later in the process.
Common Questions
Does the second staircase rule apply to existing buildings?
No. It only applies to new residential buildings, not ones already built or already underway with building control approval.
What height triggers the second staircase requirement?
18 metres. This is the same threshold used to define a “higher-risk building” under the Building Safety Act
When does the second staircase rule come into effect?
30th September 2026
Does the second staircase requirement affect fire door specification?
Yes. A second staircase typically creates new corridors, protected lobbies and risers, each of which needs its own fire door and fire stopping specification.
Get in touch with us for more information or to talk through your project, or call 0800 035 6827.
