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From 30 September 2026, updated Approved Document B guidance recommends that blocks of flats in England with a top storey 18 metres or more in height are served by more than one common stair.
For project teams, the practical response is not simply to add another staircase to the architectural drawings. A revised stair arrangement can affect corridors, protected lobbies, risers, smoke-control systems, evacuation lifts, structural openings and service routes throughout the building.
Each change creates new interfaces with fire-resisting walls and floors. Unless those interfaces are coordinated before construction, they can result in unsupported fire-stopping details, inaccessible installations, late redesign and expensive opening-up work.
This guide explains what clients, principal contractors, principal designers, specialist contractors and building managers should review before the new guidance takes effect.
Important: The September 2026 amendment does not introduce a separate statutory fire-stopping checklist. The actions below are practical measures intended to help project teams manage the passive fire protection interfaces created when stair, lobby, riser and service layouts change.
Effective date: 30 September 2026
Applies in: England
Main threshold: Blocks of flats with a top storey 18 metres or more in height
Main recommendation: Flats should be served by more than one common stair
Transition deadline: Eligible projects must be sufficiently progressed by 30 March 2028 to continue using the previous guidance
Other relevant changes: Revised horizontal and vertical escape guidance, together with provisions supporting evacuation lifts and evacuation shafts
The amended guidance also states that interlocked stairs are considered a single escape route and do not provide an alternative means of escape. citeturn582149view1turn607829view1
The 2026 amendments introduce a recommendation for more than one common stair in blocks of flats where the building has a top storey 18 metres or more in height.
The changes also restructure the guidance on horizontal and vertical escape and introduce provisions supporting the use of evacuation lifts. Where an evacuation lift is provided, the guidance describes an evacuation shaft containing a protected stairway, evacuation lift and evacuation lift lobby. citeturn592062view0turn592062view1
Approved Document B provides practical guidance on ways to meet the requirements of the Building Regulations. It is not a substitute for a competent, project-specific fire strategy, and simply following an Approved Document does not automatically guarantee compliance in every building or design situation. citeturn758010view2
Project teams should therefore confirm the applicable approach with their fire engineer, principal designer and relevant building control body.
A project that started design work before September 2026 does not automatically remain under the previous guidance.
The previous 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 work is sufficiently progressed within the transition period.
The formal transition deadline is 30 March 2028. citeturn592062view0
For these transitional arrangements, work is considered sufficiently progressed when:
These definitions are set out in Circular 04/2024. citeturn592062view0turn582149view0
Do not rely solely on the date shown on the fire strategy, planning drawings or construction programme. Record the regulatory route formally and confirm it with the project’s building control body and fire-safety advisers.
A second protected stair changes more than circulation.
It may require corridors to be rearranged, lobbies to be enlarged, risers to be relocated and mechanical or electrical services to follow different routes. Smoke-control systems, evacuation lift arrangements and structural openings may also need to be redesigned.
These changes can affect:
The objective is not simply to seal individual holes. The complete compartmentation system must maintain the fire performance required by the fire strategy.
Every wall, floor, door, shaft, cavity barrier, joint and penetration needs to work as part of that coordinated system.
Confirm the required fire resistance of each protected stair, lobby and corridor.
Review junctions at walls, floors, soffits, façades and roof areas. Pay particular attention where a fire-resisting enclosure changes direction, meets a different substrate or passes behind ceilings and building services.
Where two stairs are connected by a common corridor, the fire strategy should also address corridor subdivision, door positions and the risk of smoke affecting access to both escape routes.
Where evacuation lifts are included, coordinate the lift, protected stair, evacuation lift lobby, refuge area and surrounding fire-resisting construction as a complete arrangement.
Approved Document B states that evacuation shafts should receive the same minimum level of protection as the stairway. Smoke-control systems intended to protect the staircase should provide the same level of protection to the evacuation lift and its lobby. citeturn607829view0turn582149view2
Service penetrations, lift equipment, control systems and access panels must not undermine that protection.
Map every pipe, cable, duct, tray and containment system expected to cross a compartment wall or floor.
Do not leave service coordination until installation begins. A riser that appears workable on an MEP drawing may become impossible to fire stop correctly once multiple services, insulation systems, brackets and access requirements are considered together.
Coordinate smoke shafts, ducts, dampers, fans, builders’ work openings and access panels with the passive fire design.
The space required to inspect, test, replace and maintain a damper or smoke-control component must be considered before surrounding construction is closed.
Review slab edges, beams, columns, movement joints, deflection heads and structural connections.
These areas are frequently more difficult to inspect after completion and may require fire-stopping or joint systems capable of accommodating movement rather than a rigid seal.
The permanent fire strategy can be undermined by temporary openings and poorly controlled follow-on work.
Plan how compartment lines will be maintained during construction, who may form openings and how temporary penetrations will be recorded and closed.
Keep relevant installations visible until they have been inspected and accepted.
Where possible, programme inspection hold points before ceilings, riser walls, boxing and access panels are completed. Once an installation is concealed, verifying its construction and suitability can become expensive or inconclusive.
Record the edition of Approved Document B and the amendments that apply to the project.
Check that the fire strategy, architectural drawings, structural information, MEP design, specifications and specialist packages are aligned.
Resolve conflicts before procurement and installation begin.
A note stating “fire stop all penetrations” is not an installable design. Contractors need sufficient information to identify the required performance, substrate, service configuration, opening dimensions and suitable tested or assessed system.
Produce coordinated drawings showing:
Give the drawings controlled revision numbers and make the current versions available to every relevant trade.
Where new work connects to an existing building, consider carrying out a competent fire compartmentation survey before construction begins. This can identify missing, damaged or inaccessible barriers that may affect the proposed design.
Create a schedule for every planned service penetration.
The schedule should record:
The proposed detail must fall within the scope of the supporting evidence for the selected system.
Unusual service combinations, oversized openings or non-standard substrates should be referred to the designer and system manufacturer. They should not be improvised on site.
No trade should drill, cut or enlarge an opening through a designated fire-resisting element without approval.
A permit-to-penetrate process can:
The process must remain practical enough to be followed on site. An overcomplicated system that trades work around will not provide meaningful control.
Midsummer’s guide to controlling fire stopping during building works explains how this process can be structured.
Fire stopping should be treated as a tested or assessed system, not as an individual product.
Suitability depends on the complete configuration, including:
A product data sheet on its own does not demonstrate that a particular site installation matches the tested configuration.
Include inspection hold points in the construction programme.
Where appropriate, inspections should take place while both sides of a penetration or junction remain visible. This allows the inspector to verify elements that may be impossible to assess after ceilings or riser walls are closed.
Each record should include:
A defect should not be marked complete simply because a spreadsheet status has changed. Its closure should be supported by appropriate evidence.
Fire-stopping compliance does not end when the original installation is signed off.
Later cable additions, pipework alterations and maintenance activity can damage an otherwise suitable seal. Project teams should define how subsequent work through compartment lines will be approved, recorded and reinspected.
The final asset information should make it possible for facilities teams and future contractors to identify where fire-resisting elements are located and how they may be safely altered.
Do not leave the passive fire protection handover pack until practical completion.
Approved Document B’s Regulation 38 guidance is intended to ensure that the relevant dutyholder receives sufficient fire-safety information to understand, operate and maintain the building and its systems. The information should be provided at completion or first occupation, whichever occurs first. citeturn758010view1
For higher-risk building work, clients, principal designers and principal contractors must also maintain a digital record of relevant building information as part of the golden thread. The information should be accurate, accessible, understandable and kept up to date. citeturn748753search2
Midsummer’s guide to passive fire protection handover packs explains the records that clients and contractors should expect.
A useful record should allow another competent person to establish:
At a minimum, the project should be able to retrieve:
Photographs alone are not enough where they cannot be matched to a location, system or approved detail.
Equally, test evidence does not prove that a specific installation is suitable unless the site configuration falls within its scope.
Good evidence combines technical suitability with site-specific traceability.
The stair arrangement may affect MEP routes, risers, corridors, smoke control, evacuation lifts and passive fire protection throughout the building.
A superseded fire strategy can result in different design teams working to incompatible assumptions.
The governing strategy and drawings should be controlled before specialist packages are released.
Fire resistance is demonstrated by a complete tested or assessed configuration. Selecting a branded sealant, collar or batt does not prove that every proposed installation is supported.
Service routes should be designed with an installable fire-stopping solution in mind. Trying to find a system after the opening has been formed can lead to unsupported combinations or unnecessarily extensive remedial work.
Large openings containing cables, trays, pipes, insulation and ducts are rarely straightforward.
Service spacing and support arrangements can be as important as the selected sealing product.
Concealed installations without sufficient evidence may require intrusive inspection or opening-up before they can be accepted.
A site variation may be technically reasonable but still needs to be reviewed, approved and reflected in the as-built information.
Project teams should be able to answer the following:
The changes take effect in England on 30 September 2026, subject to the formal transitional arrangements. citeturn592062view0
The amended guidance recommends more than one common stair where a block of flats has a top storey 18 metres or more in height.
Mixed-use, unusual and complex buildings may require project-specific interpretation by suitably competent advisers.
Approved Document B refers to the building’s top storey and directs users to the measurement method shown in Diagram D6 of the document.
The project team should use the formal measurement method rather than relying on the building’s marketing height, total structural height or number of storeys.
For construction of a new building, work is sufficiently progressed when permanent foundation concrete has started to be poured or permanent piling has started.
For work to an existing building, the relevant work must have started. For a material change of use, work to bring about the change must have started. citeturn582149view0
The amendment does not set out an automatic blanket requirement to retrofit every existing occupied block simply because it exceeds 18 metres.
Approved Document B applies in the context of Building Regulations-controlled building work and material changes of use. Work to an existing building should therefore be assessed according to its scope, regulatory route and fire strategy. citeturn758010view0turn758010view1
No. The amended guidance states that interlocked stairs should be treated as a single escape route and do not constitute an alternative means of escape. citeturn582149view1
No.
Means of escape and passive fire protection perform different but connected functions. Fire-resisting walls, floors, doors, shafts, cavity barriers and penetration seals remain essential to limiting the spread of fire and smoke in accordance with the fire strategy.
Specialist input should be obtained before relevant service routes, openings and construction packages are fixed.
Early review can identify unsupported penetration details, unsuitable service spacing, sequencing problems and inadequate inspection access before they become costly site defects.
The September 2026 changes are an important design milestone, but much of the delivery risk sits in the interfaces between design packages and trades.
Project teams that identify compartment lines early, coordinate service penetrations, inspect work before concealment and maintain traceable records are better placed to avoid late opening-up, unsupported installations and uncertain handovers.
Midsummer Fire Protection supports commercial and residential project teams with fire compartmentation surveys, fire-stopping installation, passive fire inspections and evidence-led remedial works.
Request a pre-construction passive fire review to identify potential compartmentation and fire-stopping risks before work is concealed.
