Changes to Approved Document B take effect in England on 30 September 2026. The amendments introduce a recommendation for more than one common stair in blocks of flats with a storey 18m or more above ground level, together with design provisions supporting evacuation lifts. These changes sit alongside existing sprinkler requirements, including earlier provisions for flats and care homes.
For developers, architects and contractors, the practical task is to establish which version of the guidance applies and make sure the fire strategy, suppression specification and building design agree.
NPHS supports domestic, residential and commercial project teams with sprinkler, water mist and specialist fire suppression design, installation, commissioning and maintenance.
What changes to Approved Document B take effect in September 2026?
The 2026 amendment booklet takes effect on 30 September 2026, subject to transitional provisions.
The government identifies two main changes.
The first is a new recommendation for more than one common stair in blocks of flats where a storey is 18m or more above ground level.
The second introduces building-design provisions intended to support the use of evacuation lifts in blocks of flats.
These are important residential design changes, but they should not be confused with the separate sprinkler amendments introduced in previous updates.
That distinction matters when reviewing a fire strategy dated 2024, 2025 or 2026.
Approved Document B: Sprinklers & Water Mist
Does the September 2026 amendment introduce new sprinkler requirements?
The main September 2026 amendments concern second stairs and evacuation-lift provisions rather than introducing a new general sprinkler threshold.
Recent sprinkler changes came through earlier updates.
Approved Document B already provides for sprinklers in new blocks of flats where the top storey is more than 11m above ground level.
Separately, guidance requiring sprinkler provision in all new care homes regardless of height took effect on 2 March 2025.
Project teams reviewing the 2026 changes should therefore consider the current guidance as a whole rather than treating 30 September as the starting date for every recent fire-safety amendment.
What is changing for residential buildings at 18 metres?
From 30 September 2026, Approved Document B includes a recommendation for more than one common stair in blocks of flats with a storey 18m or more above ground level.
The 18m threshold followed consultation on second staircases in taller residential buildings.
For project teams, this has wider consequences than simply drawing another staircase.
It can affect:
- Floor planning
- Cores
- Circulation
- Apartment layouts
- Smoke control
- Firefighting access
- Evacuation arrangements
- M&E coordination
Fire suppression remains part of that wider fire-safety design.
A sprinkler system does not remove the need to review other provisions required by the current guidance.
Why does this matter to fire suppression contractors?
Suppression does not sit in isolation.
If a residential scheme changes because of the new stair or evacuation arrangements, the suppression design may also need reviewing.
Changes to cores, corridors, apartment layouts, risers and plant spaces can affect pipe routes, sprinkler-head positions, zoning and access for future maintenance.
A project that was coordinated before the second-stair design was finalised may therefore need another suppression review.
That is particularly important where the fire strategy itself has been updated.
Residential Fire Sprinkler & Water Mist Systems
What are the transitional arrangements for the 2026 changes?
The transitional arrangements deserve close attention on projects already in design or pre-construction.
The 2026 amendments take effect on 30 September 2026.
The earlier version 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 that date and the building work either:
- Has started and is sufficiently progressed before 30 September 2026.
- Is started and becomes sufficiently progressed within the 18-month period beginning on 30 September 2026.
The government defines what “sufficiently progressed” means for different types of work.
For new construction, this includes commencement of specified permanent foundation works. For work to an existing building, the work must have started. For a material change of use, work to effect that change must have started.
Project teams should work from the exact government wording rather than assumptions about when a project was “started”.
What should developers check on projects crossing the September 2026 date?
Start by identifying the regulatory position of the project.
A development designed several years ago may now sit close to a major transition date.
The design team should confirm which edition and amendments of Approved Document B form the basis of the fire strategy and whether the transitional provisions apply.
Then compare that position with the current architectural and M&E design.
A useful review should answer:
| Question | Why it matters |
|---|---|
| When was the Building Control application made? | Helps establish the relevant transition route |
| Has the work sufficiently progressed? | Determines whether transitional provisions may apply |
| Which ADB version does the fire strategy reference? | Older strategies may refer to earlier guidance |
| Does the building reach the 18m threshold? | May trigger the new stair recommendation |
| Has the core layout changed? | Can affect suppression pipework and risers |
| Is sprinkler protection required? | Needs to be reflected in the system specification |
| Has the suppression design been updated? | Layout changes may alter coverage and coordination |
Where any of those answers are uncertain, resolve them before installation.
What sprinkler requirements already apply to blocks of flats?
Approved Document B Volume 1 already includes sprinkler guidance for blocks of flats.
In England, blocks of flats with a top storey more than 11m above ground level should be fitted with a sprinkler system throughout the building in accordance with the guidance.
That 11m sprinkler provision and the new 18m second-stair provision are separate requirements.
A residential building may therefore cross the sprinkler threshold before it reaches the second-stair threshold.
This is why a project should not be reduced to one shorthand height figure.
The fire strategy needs to consider the relevant provisions together.
Fire Suppression for Flats & Apartments
What changed for care-home sprinklers?
The care-home sprinkler change came into effect on 2 March 2025, rather than September 2026.
Approved Document B was updated to provide for sprinklers in all new care homes regardless of building height.
This is particularly relevant to developers, architects, operators and consultants working in residential care.
The suppression design should be considered alongside occupancy needs, evacuation strategy, system reliability, water supply, plant space and future maintenance.
Care projects also need careful coordination between the wider fire strategy and the sprinkler standard used for the installation.
Which sprinkler standard might apply?
Approved Document B identifies the regulatory guidance context. The sprinkler system itself then needs an appropriate design standard.
For domestic and residential occupancies, BS 9251:2021 may be relevant.
The correct system category depends on factors including building type, height, occupancy and risk. That can influence system performance, water storage, pumps and resilience.
For project teams, it is useful to separate two questions:
- Does the Building Regulations route require sprinkler protection?
- What sprinkler standard and category should the installed system follow?
Those questions are related, but they are not identical.
How does BS 9991 fit with Approved Document B?
BS 9991:2024 is a code of practice for fire safety in residential buildings.
Approved Document B is statutory guidance supporting the Building Regulations in England.
Both may be relevant on the same residential project, but they serve different purposes.
BS 9991 can form part of the wider residential fire-safety design route, while Approved Document B provides government guidance on meeting Building Regulations requirements.
The current BS 9991:2024 position is also significant for suppression because its fixed-firefighting recommendations now refer specifically to sprinkler systems.
Where a project is using both Approved Document B and BS 9991, the fire strategy should make the chosen route clear.
BS 9991 Water Mist & Sprinkler Systems
Can water mist be used where Building Control asks for fire suppression?
Water mist can be considered on some projects where it is technically suitable and supported through an appropriate project-specific route.
Where Approved Document B specifically recommends sprinklers, a proposal to use water mist should not assume that the two systems are automatically interchangeable.
The project team needs to establish the technical basis for any alternative proposal.
That may include the fire strategy, relevant BS EN 14972 standards, system fire-test evidence, product certification and review by the relevant approving parties.
NPHS can support the suppression element by providing technical system information, installation details, commissioning documentation and maintenance requirements.
Final acceptance remains with the relevant project and approval route.
What current standards apply to residential water mist?
The standards position for residential water mist changed significantly in 2025.
BS 8458:2015 was withdrawn by BSI in July 2025.
Current residential water mist projects should consider the relevant BS EN 14972 framework, including BS EN 14972-17:2025 for the residential occupancy fire-test protocol and the relevant design, installation, inspection and maintenance requirements.
Older Building Control correspondence or specifications referring to BS 8458 should therefore be reviewed rather than copied into a new project without checking the current position.
What about domestic loft conversions and open-plan homes?
The September 2026 second-stair change is aimed at taller residential buildings, so it should not be confused with the Building Control issues that arise on individual domestic alterations.
Homeowners may encounter fire suppression discussions during:
- Loft conversions
- Open-plan alterations
- Extensions
- Changes to protected escape routes
- Substantial refurbishments
For those projects, the exact requirement depends on the proposed layout and Building Control route.
Water mist or domestic sprinklers may form part of the solution, but the system should be considered within the wider fire-safety design.
Do the 2026 changes apply across the whole UK?
No.
Approved Document B discussed here applies to England.
Wales, Scotland and Northern Ireland have their own Building Regulations or building-standards frameworks.
This distinction is particularly important for companies working nationally.
A project in Cardiff, Glasgow and Manchester should not be given the same Building Regulations answer simply because the buildings look similar.
Project location should be established before giving standards or compliance guidance.
Is Approved Document B still being reviewed?
Yes.
In March 2026, the Building Safety Regulator and government opened a further consultation on Approved Document B. The consultation closed on 1 July 2026.
The proposals include potential updates relating to work on existing buildings, external walls and balconies, evacuation lifts, specialised housing, roofs and photovoltaic panels, and open-sided car parks.
At the time of writing, those consultation proposals should not be presented as final requirements.
This page should be reviewed when government publishes the consultation outcome or further amendments.
Why should specifications use exact editions and dates?
Fire-safety standards and statutory guidance change.
Writing simply “to current Building Regulations” may sound safe, but it can leave design teams and contractors unclear about the actual basis of the project.
A stronger specification records:
- The Approved Document edition and relevant amendments
- Applicable British Standards
- Fire-strategy revision
- Sprinkler or suppression system type
- Project-specific approval route
That creates a clearer record when the project moves from design to procurement and finally to commissioning.
It also becomes useful years later when the building owner needs to understand why the system was installed.
What should main contractors check before appointing the suppression contractor?
Before placing the package, compare the fire strategy, architect’s drawings, M&E specification and suppression tender documents.
They should tell the same story.
Confirm the required system, protected areas, standard, water-supply assumptions, design responsibility and commissioning requirements.
If the project is near the September 2026 transition, make sure the wider design team has confirmed which Approved Document B provisions apply.
The suppression contractor should not be left to decide the regulatory route after the order is placed.
What happens if drawings change because of the second staircase?
Send the revised drawings to the suppression designer.
Changes to cores, corridors, apartments, ceilings or plant areas can affect the suppression design.
Even where the number of sprinkler heads changes very little, pipe routing and riser coordination may change significantly.
The final suppression design should reflect the building being constructed rather than an obsolete architectural revision.
What information should you send NPHS?
For an early review, send the latest drawings, fire strategy and any Building Control comments.
If the project is affected by the September 2026 transition, include the relevant Building Control application information and current project programme where available.
NPHS can review the suppression scope and advise on practical matters including the proposed sprinkler or water mist system, water supply, plant space, installation coordination, commissioning and maintenance.
Frequently asked questions
What Approved Document B changes take effect on 30 September 2026?
The 2026 amendments principally introduce a recommendation for more than one common stair in blocks of flats with a storey 18m or more above ground level and design provisions supporting evacuation lifts. Transitional arrangements apply to qualifying projects already in progress.
Does the 2026 Approved Document B amendment change the sprinkler threshold for flats?
The September 2026 amendments are primarily concerned with second staircases and evacuation-lift provisions. Approved Document B already includes separate sprinkler guidance for blocks of flats where the top storey is more than 11m above ground level.
When did the new sprinkler requirement for care homes take effect?
The Approved Document B amendment providing for sprinklers in all new care homes regardless of height took effect in England on 2 March 2025. It is separate from the September 2026 second-stair amendment.
Can water mist be used instead of sprinklers under Approved Document B?
Water mist may be considered through a project-specific route where it is suitable and supported by appropriate technical evidence. Where Approved Document B specifically recommends sprinklers, water mist should not be assumed to be automatically equivalent. The fire strategy and relevant approving parties need to consider the proposal.
Can NPHS review a project affected by the 2026 Approved Document B changes?
Yes. NPHS can review the drawings, fire strategy, Building Control comments and suppression specification and advise on sprinkler, water mist or specialist suppression requirements, installation planning, commissioning and maintenance. The applicable Building Regulations route should remain agreed by the project team and relevant Building Control body.
Need fire suppression support on a project affected by Approved Document B?
NPHS works with developers, contractors, architects, fire consultants, housing providers, homeowners and property teams across the UK.
For projects in England, we can review the suppression requirements alongside the relevant Approved Document B route and project information.
Send us your drawings, fire strategy, Building Control comments, sprinkler or water mist specification, project programme and water-supply information.
We can then advise on the practical suppression system requirements and next steps.
Send project details for review
Primary sources: GOV.UK 2026 amendments to Approved Document B; GOV.UK Approved Document B, Fire Safety; GOV.UK Review of Approved Document B consultation.