Second staircases in residential buildings: what you need to know

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From 30 September 2026, new residential buildings in England that exceed 18 metres in height must include a second independent staircase. The new rule, delivered through amendments to Approved Document B (Fire Safety), affects a far wider range of schemes than many had first anticipated.

This article explains what has changed, key dates to note, and the practical steps developers and funders can be taking.

Background

The second staircase requirement stems directly from the Grenfell Tower fire, which raised urgent questions about whether single-staircase high-rise residential buildings provided adequate means of escape in an emergency. That debate has now been resolved with a firm policy position and a clear compliance deadline.

In February 2023, the Greater London Authority announced that all planning applications for residential buildings over 30 metres in London would need to include at least two staircases in order to be considered by the Mayor of London for final approval. Those already working on developments in London will therefore be familiar with the second staircase requirement and the design considerations it raises.

The government subsequently announced a nationwide policy. In October 2023, the then Housing Secretary made a statement to Parliament setting out how the second staircase requirement for residential buildings over 18 metres would be taken forward. The requirement would be embedded in an updated Approved Document B, with transitional arrangements published alongside it, giving developers a 30-month window from the date of publication during which they could choose to follow either the existing or the updated requirements. The updated Approved Document B sits alongside the Building Regulations 2010 (SI 2010/2214)Opens in a new window (BR 2010). and provides technical guidance as to how compliance with the regulations can be demonstrated.

For more information, see:

• Legal update, Government confirms 18-metre second staircase threshold.
• Toolkit, Building safety toolkit: Second staircase requirements.
• Practice note, Building regulations: an overview.

A note on transition

If a project falls into the transitional period (as set out below) then the new regime will not apply to it.

For projects in the transitional period (those for which a building notice, initial notice, or building control approval application with full plans was submitted to the relevant authority before 30 September 2026), developers must have notified the relevant building control authority that the project is "sufficiently progressed" by 30 March 2028 or the project will fall under the new regime.

For new construction, the test to show whether works are "sufficiently progressed" is that concrete pouring has started for the permanent placement of trench, pad, or raft foundations, or for the permanent placement of piling.

Developers must notify the relevant building control authority within five working days of reaching this stage. A construction programme that shows foundations starting is not enough; they need to have actually started.

Key requirements of new regime

The 30-month transition period for the second staircase requirement comes to an end on 30 September 2026 and from this date the following buildings must be designed and built with two independent staircases:

• Any new residential or mixed-use building with residential units in England over 18 metres.
• Any building (regardless of height) where:
  • there are flats that are not separated from the common stair by a protected lobby; or
  • a maximum travel distance of 7.5m in one direction or 30m in multiple directions is exceeded.

The second staircase requirement does not apply to airspace developments that turn existing buildings into buildings above 18 metres nor does it apply to existing buildings over 18 metres with a single staircase.

For higher-risk buildings (buildings over 18 metres or seven storeys with at least two residential units), compliance with the second staircase requirement is embedded directly into the gateway process; it forms part of the fire safety review at gateway one (planning) and must be demonstrated to the Building Safety Regulator at gateway two (building control approval) before construction can begin. The result is that staircase strategy, fire safety design, structural co-ordination and buildability are now linked; a weakness in any one of them puts the entire approval at risk. From a practical perspective, this is not something that can be easily resolved as design evolves, it has to be settled from the outset.

For more information, see:

Practice notes:

• BSA 2022: what is a higher-risk building?;
• BSA 2022: higher-risk buildings and the gateways regime.
• Checklist for airspace development.

Dates to note

• 30 September 2026: The new requirement comes into full effect. As outlined above, from this date, all new residential and mixed-use buildings with residential units in England over 18 metres seeking building regulations approval, as well as certain buildings under 18 meters that don't meet specified requirements, must include a second staircase.
• 30 March 2028: "In-flight" projects must be "sufficiently progressed" by this date in order to proceed under the old rules (and developers must notify the relevant building control authority within five working days of reaching this stage). Projects that miss this deadline must comply with the new requirements.

Key takeaways

There are several points from the updated Approved Document B and associated guidance that developers and their teams need to keep in mind:

• The second staircase requirement is not for higher-risk buildings only: As explained above, while the new regime will capture higher-risk buildings, it will also capture buildings below 18 metres in certain scenarios. Always check whether the rules affect your project at the outset.
• Scissor and interlocked stairs do not count as two staircases: The updated Approved Document B is explicit; interlocked, stacked, or scissor stairs are treated as a single escape route and will not be accepted as two independent means of escape. This is because scissor stairs lack sufficient fire and smoke separation between the intertwined flights. Any scheme relying on this approach will not comply.
• Non-compliance carries severe consequences: Failure to comply with the BR 2010 is a criminal offence in England, carrying an unlimited fine and, on conviction on indictment, up to two years' imprisonment. Enforcement action can include compliance notices, stop notices, injunctions, and the requirement to remove or alter non-compliant work. Practically, non-compliance also means no completion certificate, which makes the building effectively unsaleable.

Final thoughts

For developers and their funders, the key is to understand whether the new regime applies to their projects. If the project has the benefit of transition and so falls outside the new regime, certain steps must be taken after 29 September 2026 to ensure that the project continues to benefit from this exemption. It is critical that these parties understand what they need to do and by when.

For projects which will fall within the new regime, the key is to work with the design team to ensure that the requirements of the new regime are met in full.

For funders, the transitional period creates a specific and time-limited monitoring obligation: projects where a building notice, initial notice, or building control approval application with full plans was submitted to the relevant authority before 30 September 2026 but fail to commence foundations by 30 March 2028 will need to comply with the new requirement, potentially requiring redesign and additional costs.

Lenders and investors should treat this as a due diligence point, asking developers directly how they are managing the transition. For example, checking whether a gateway two application for building control approval predates 30 September 2026, confirming whether the construction programme shows works are sufficiently progressed before 30 March 2028, reviewing whether the staircase design has been signed off by the fire consultant, and ensuring that drawdown conditions, risk registers and project documentation properly reflect this.

The key question is not simply whether a scheme can meet the second staircase requirement, but whether it is still viable after meeting it. The earlier that question is stress-tested against the original appraisal, the more options remain on the table.

A version of this article was published in PLC Construction on 6 July 2026