IN Brief:
- The 2026 Approved Document B amendments apply from 30 September to blocks of flats with a storey 18 metres or more in height.
- Eligible projects using the previous guidance must have been submitted before the effective date and become sufficiently progressed by 30 March 2028.
- The update also restructures escape guidance and introduces provisions covering evacuation shafts and evacuation lift arrangements.
Ministry of Housing, Communities and Local Government guidance requiring provision for a second staircase in taller residential buildings takes effect in England today, 30 September 2026.
The change is contained in the 2026 amendments to Approved Document B and applies to blocks of flats with a storey 18 metres or more above ground level.
The amendment introduces a height threshold at which a single common stair is no longer the expected design approach for blocks of flats. The revised guidance states that buildings at or above the threshold should be served by more than one common stair, bringing the provision into the same height range used elsewhere in the building safety regime for higher risk residential buildings.
The 2026 amendment extends beyond the numerical threshold. Section 3 of Approved Document B has been restructured to separate provisions for horizontal and vertical escape, while the guidance introduces the concept of evacuation shafts to support evacuation lifts where they are provided.
New terminology includes evacuation shaft, evacuation lift lobby, interlocked stair and storey exit, giving designers and building control professionals a more explicit vocabulary around vertical escape arrangements.
Transitional provisions remain available for schemes already in the pipeline. The previous 2019 edition, incorporating the 2020, 2022 and 2025 amendments, can continue to apply where a building notice or initial notice was given, or a building control approval application with full plans was made, before 30 September 2026.
Those projects must also become sufficiently progressed before 30 March 2028. For a new building, that means pouring concrete for permanent trench, pad or raft foundations has started, or permanent piling has begun.
For work to an existing building, the relevant work must have started, while for a material change of use, work to effect that change must have begun. The transition therefore depends on both the date of the building control route and demonstrable physical progress, rather than planning status alone.
The 18-metre threshold was confirmed after consultation. Government had initially consulted on a 30-metre trigger before deciding that new tall residential buildings at 18 metres and above should make provision for a second staircase.
Its stated rationale was to provide an alternative route for residents if an escape route becomes congested or compromised, while also improving access arrangements for emergency services.
Approved Documents provide statutory guidance on ways of satisfying the functional requirements of the Building Regulations; they are not simply design guidance attached to planning. From today, the revised text becomes the reference point for common compliance solutions moving through building control.
Alternative approaches remain possible within the performance based Building Regulations framework, but they must demonstrate that the relevant fire safety requirements are met rather than simply reproduce a layout accepted under an earlier edition.
Adding a second protected common stair can affect core dimensions, net-to-gross efficiency, structural grids, façade layouts, lift and service coordination, circulation space and the relationship between apartments and escape routes. On schemes still at design stage, those interfaces have to be resolved before structural and building services packages are fixed.
Projects relying on the transitional arrangements also need clear evidence that the relevant notice or application was made before the deadline and that construction reaches the required stage by March 2028.
Recent higher rise residential schemes have already been moving through the Building Safety Regulator’s Gateway 2 process with dual stair arrangements. A Leeds residential scheme cleared through Gateway 2 earlier this month shows the design requirement already influencing live project delivery.
The second stair amendment also sits within a wider sequence of changes to Approved Document B. Amendments that came into force in March 2025 addressed sprinklers in care homes and removed references to BS 476 for reaction to fire and roof classifications.
A further amendment is scheduled for September 2029 to remove BS 476 references for fire resistance, continuing the shift towards the European classification route.
For projects not protected by the transition, 30 September 2026 is now the operative date. Design teams, contractors and building control bodies must establish which edition of Approved Document B applies and ensure that drawings, specifications and construction sequencing align with that position.
The final transition deadline for eligible existing applications is 30 March 2028, after which the earlier guidance can no longer be relied upon for projects that have failed to reach the prescribed stage of construction.
