The Approved Document B changes in 2026 take effect in England on 30 September. The principal amendment introduces a recommendation for more than one common stair in blocks of flats where the building has a top storey 18 metres or more above ground level. The revised guidance also introduces provisions intended to support the use of evacuation lifts in blocks of flats. It restructures parts of the guidance dealing with horizontal and vertical escape and introduces several new terms connected with evacuation shafts and stair design.
Developers, architects and design teams should establish which version of the guidance applies to their project before relying on an existing design. Projects submitted before the implementation date may benefit from transitional arrangements, but only where the relevant submission and commencement conditions are met.
What is changing in Approved Document B in September 2026?
The September 2026 amendments primarily affect Approved Document B Volume 1, which provides fire safety guidance for dwellings in England.
The main changes include:
- A recommendation for more than one common stair in blocks of flats with a top storey 18 metres or more above ground level.
- New provisions supporting evacuation lifts where they are provided.
- The introduction of the concept of an evacuation shaft.
- Revised guidance separating horizontal escape from vertical escape.
- New definitions, including evacuation shaft, evacuation lift lobby, interlocked stair and storey exit.
The official Approved Document B amendments and current editions should be reviewed alongside the relevant project documents. The applicable guidance depends on the nature of the building work, its submission date and whether the transitional provisions are satisfied.
Does Approved Document B become law on 30 September 2026?
Approved Document B is statutory guidance supporting the fire safety requirements of the Building Regulations 2010. It is not itself legislation.
The Building Regulations contain functional requirements that applicable building work must satisfy. Approved Documents describe approaches that may, in ordinary circumstances, be accepted as a way of meeting those requirements.
Following an Approved Document does not automatically guarantee that a project complies with the Building Regulations. The guidance cannot cover every building form, use, risk or design arrangement. The design team must still consider whether the recommended approach is suitable for the particular project.
Alternative solutions may also be possible where they are properly developed, justified and documented through an appropriate fire engineering approach.
This distinction is important. The September 2026 update changes the published guidance used to support Building Regulations compliance in England; it does not replace the underlying functional requirements.
What is the new second staircase recommendation?
From 30 September 2026, Approved Document B Volume 1 recommends that flats should be served by more than one common stair where the building has a top storey 18 metres or more in height.
The measurement relates to the height of the top storey in accordance with the method set out in Approved Document B. It should not be assumed that this is always the same as the overall roof height, parapet height or the height stated in planning material.
The amended guidance also states that interlocked stairs should be treated as a single escape route and do not constitute alternative means of escape.
Consequently, simply placing two stairs close together or connecting them through arrangements with common points of failure may not satisfy the intention of providing alternative escape routes.
The design must be considered as a coordinated whole, including:
- The independence and separation of the stairs.
- Horizontal escape from flats.
- Access to each storey exit.
- Travel distances.
- Corridor and lobby arrangements.
- Smoke control.
- Firefighting access.
- Structural fire resistance.
- Evacuation provisions.
- The relationship between stairs, lifts and ancillary accommodation.
Project teams should avoid treating the amendment as a requirement that can be resolved by adding another staircase to a developed layout without reviewing the remainder of the fire strategy.
The revised escape arrangement can affect the building core, net-to-gross floor area, structural grid, service distribution, façade arrangement, planning layout and construction cost. Early coordination is therefore preferable to redesigning the scheme after planning or building control submission.
Does every residential building over 18 metres need two stairs?
The September 2026 guidance specifically refers to blocks of flats with a top storey 18 metres or more in height.
However, the correct approach cannot be determined from building height alone. The building use, layout, applicable guidance, regulatory route and scope of work must also be established.
Different considerations may apply to:
- Hotels.
- Care homes.
- Student accommodation.
- Houses in multiple occupation.
- Mixed-use developments.
- Conversions of existing buildings.
- Extensions to existing residential buildings.
- Buildings containing both flats and other residential accommodation.
Approved Document B Volume 1 and Volume 2 have different scopes. Other guidance or a fire-engineered approach may also be relevant depending on the project.
A project should therefore not be described simply as “residential” and assessed against the two-stair recommendation without first confirming its purpose group, use and applicable design basis.
Do the 2026 changes require evacuation lifts?
The September 2026 amendments introduce building design provisions to support evacuation lifts in blocks of flats where evacuation lifts are provided.
They do not, by themselves, establish a general requirement for evacuation lifts in every block of flats.
The amended guidance states that, where an evacuation lift is provided, it should be located within an evacuation shaft containing:
- A protected stairway.
- The evacuation lift.
- An evacuation lift lobby.
The evacuation lift lobby should provide a refuge area for people waiting for the lift. It should have direct access to a protected stairway and should not be directly accessible from a flat, maisonette, storage room or electrical equipment room.
These provisions recognise that evacuation lift design cannot be considered separately from the protected escape core. The lift, lobby, stair, power supplies, fire-resisting construction, communication arrangements and management procedures must operate as a coordinated system.
Detailed specialist lift design would normally be completed by the relevant competent lift designer or specialist. The fire strategy should establish the required fire safety objectives and coordinate the evacuation lift with the wider means-of-escape strategy.
The Government has separately consulted on further revisions to Approved Document B, including wider proposals for evacuation lifts in taller residential buildings. Those proposals should not be confused with the amendments already scheduled to take effect in September 2026. Consultation proposals are not settled requirements unless and until the resulting changes are formally adopted.
What is an evacuation shaft?
An evacuation shaft is a protected enclosure containing the components needed to support evacuation by lift.
Under the revised guidance, this includes the protected stairway, evacuation lift and evacuation lift lobby. The arrangement is intended to provide a protected route and waiting area for occupants who may be unable to use the stairs independently.
An evacuation shaft is not simply a standard passenger lift placed next to a staircase. Its fire resistance, lobby protection, controls, power arrangements and operational procedures must be considered as part of the building’s fire safety design.
The strategy should also identify how the evacuation lift will be operated. Depending on the building and proposed system, this may require trained management, defined communication arrangements and appropriate emergency procedures.
When do the Approved Document B changes take effect?
The amendments take effect on 30 September 2026 for use in England.
From 1 October 2026, new applications will need to be considered against the revised guidance, subject to the specific legal and procedural context of the project.
The Government has provided transitional arrangements for some projects submitted before the change takes effect. However, submitting an application before the deadline does not necessarily allow a project to use the previous guidance indefinitely.
How do the transitional arrangements work?
The earlier edition of Approved Document B can continue to apply where the relevant building notice, initial notice or building control approval application with full plans was made before 30 September 2026 and the associated building work:
- Was started and sufficiently progressed before that date.
- Is started and sufficiently progressed within the following 18-month period.
For a new building, work is regarded as sufficiently progressed when the pouring of concrete for the permanent placement of trench, pad or raft foundations has started, or when the permanent placement of piling has started.
For work to an existing building, the relevant work must have started. For a material change of use, work intended to bring about that change of use must have started.
Project teams should not assume that site clearance, demolition, temporary works, procurement activity or preliminary enabling works will necessarily satisfy the definition of sufficiently progressed.
The transition should be checked against the precise project circumstances and the formal government provisions. The building control approval route may also affect which submission terminology is relevant.
Where there is uncertainty, the position should be confirmed before the design team commits to a layout based on the earlier guidance.
What should developers and design teams do now?
Projects that may be affected should be reviewed before 30 September 2026 rather than waiting for the amendment to take effect.
Confirm the building height correctly
Establish the top-storey height using the relevant measurement method in Approved Document B. Do not rely solely on the overall building height or planning drawings.
Confirm the building use
Determine whether the development is a block of flats or another form of residential accommodation. Mixed-use and sui generis developments may require more detailed consideration.
Review the building control programme
Identify the intended submission date, approval route and planned commencement date. Check whether the programme can realistically satisfy the transitional conditions.
Review the core arrangement
Determine whether the proposed stairs are independent and whether occupants have suitable access to alternative escape routes.
Coordinate evacuation provisions
Where evacuation lifts are proposed, ensure sufficient space has been allowed for the evacuation shaft, protected stair and lift lobby.
Update the fire strategy
The fire strategy should clearly identify:
- The applicable edition of Approved Document B.
- The project’s height and use classification.
- The number and arrangement of common stairs.
- The means-of-escape assumptions.
- The evacuation approach.
- Any evacuation lift provisions.
- Smoke control arrangements.
- Firefighting access.
- Any alternative or fire-engineered solutions.
J.S.O’s Fire Strategy Plans and Fire Engineering services can support this coordination before the design becomes fixed.
Can a single-stair design still be submitted before September 2026?
A single-stair design may fall within the transitional arrangements where the required application is made before 30 September 2026 and the work is sufficiently progressed within the specified period.
However, transitional eligibility should not be the only consideration.
Developers and designers may also need to consider:
- Planning authority expectations.
- Building Safety Regulator scrutiny for higher-risk building work.
- Fire and rescue service consultation.
- Future marketability.
- Insurer and funder requirements.
- Resident evacuation needs.
- Potential future changes to guidance.
- The practicality of starting and progressing work within the transition period.
A design that can technically rely on transitional provisions may still face wider commercial, regulatory or operational questions. These should be addressed transparently through the project fire strategy and design risk-management process.
How do the changes affect existing buildings?
The principal second-stair recommendation concerns the design of blocks of flats and does not automatically create a requirement to add a second staircase to every existing residential building over 18 metres.
Existing buildings should be assessed according to their construction, use, evacuation strategy, fire precautions, applicable legislation and the nature of any proposed building work.
Where an existing building is being extended, converted or materially altered, the project team should consider:
- Which parts of the Building Regulations apply to the proposed work.
- Whether the work makes existing conditions no worse.
- Whether consequential or interface issues arise.
- Whether the evacuation strategy remains suitable.
- Whether the current fire strategy accurately records the building.
- Whether proposed alterations affect the escape stairs or protected core.
An existing building with incomplete or outdated fire safety information may require a retrospective fire strategy or technical assessment. However, the September 2026 amendments should not be applied retrospectively without considering the building’s original design basis and legal context.
Why is an early fire strategy review important?
Stair numbers, core layouts and evacuation lift provisions have a major influence on architectural design. Resolving these matters late can lead to:
- Loss of usable floor area.
- Planning amendments.
- Structural redesign.
- Changes to smoke-control systems.
- Altered service routes.
- Delayed building control submissions.
- Abortive consultant work.
- Programme and procurement disruption.
A pre-construction fire safety review can identify these issues before the design is released for construction.
Where evacuation provisions require further development, the project may also benefit from a coordinated evacuation plan and strategy review.
How can J.S.O Fire Safety Consultants assist?
J.S.O Fire Safety Consultants can review proposed developments against the September 2026 Approved Document B amendments and establish how the changes interact with the wider fire strategy.
Our support may include:
- Reviewing the building height, use and applicable guidance.
- Assessing proposed stair and escape arrangements.
- Developing or updating the project Fire Strategy Plan.
- Coordinating evacuation lift performance requirements within the strategy.
- Reviewing architectural drawings before submission.
- Identifying potential transitional issues.
- Advising on alternative fire-engineered solutions where prescriptive guidance does not suit the project.
- Supporting design-team discussions and building control responses.
J.S.O can establish the required fire safety performance for smoke control, evacuation lifts and other specialist systems. Detailed specialist system design should be undertaken by the relevant competent designer.
Developers, architects and contractors with schemes that may be affected by the September 2026 changes can submit their drawings and project information to J.S.O for review and quotation.
