BS 9991:2024 changed the position for fixed firefighting systems in residential buildings. The revised standard now refers specifically to sprinkler systems, rather than treating other suppression technologies within the same recommendations. Where water mist is proposed, project teams need to establish a separate technical route using the relevant water mist standard, supporting test evidence and project-specific approval process.
For architects, fire consultants, developers and contractors, that distinction matters before specification is fixed.
NPHS supports residential sprinkler, water mist and specialist suppression projects from early design review through to installation, commissioning and maintenance.
What is BS 9991:2024?
BS 9991 is the British Standard code of practice for fire safety in the design, management and use of residential buildings.
The current edition is BS 9991:2024, which superseded BS 9991:2015. BSI published the current standard on 24 September 2025.
It is relevant to a wide range of residential environments, including self-contained dwellings, blocks of flats, residential accommodation blocks, specialised housing and care homes.
For project teams, BS 9991 sits within the wider fire-safety strategy. It is not simply a sprinkler installation manual.
It deals with matters including escape, fire resistance, smoke control, building management and firefighting provisions, with fixed firefighting forming one part of the overall strategy.
BS 9991 Water Mist & Sprinkler Systems
What changed in BS 9991:2024?
Several parts of the standard were updated.
BSI identifies changes including an expanded scope covering residential care, revised recommendations around sprinklers and single-stair buildings, changes to structural material provisions, revised fire-door classifications, updates to smoke control and evacuation lifts, and a 100 metre height cap within the scope of the standard.
For fire suppression specialists, however, one change deserves particular attention.
The fixed firefighting recommendations now refer solely to sprinkler systems.
BSI explains that this change was made because of what it describes as a lack of sufficient evidence supporting the efficacy of other systems within the context of BS 9991 at this time.
That means a water mist proposal should not be presented as though BS 9991 itself provides the same prescriptive route for it.
Does BS 9991:2024 still cover water mist systems?
Not in the same way as the previous industry discussion around BS 9991 sometimes suggested.
The current edition refers to sprinkler systems within its fixed firefighting recommendations.
That does not mean water mist has disappeared as a fire suppression technology for residential buildings. It means the technical case for water mist needs to be established through the relevant water mist standards, test evidence, fire strategy and approval route.
This distinction is important.
A specification that simply says:
“Provide water mist in accordance with BS 9991.”
would now need careful review.
A more useful project approach is to identify why suppression is required, what BS 9991 expects from the wider residential fire strategy, and then separately establish the technical basis for any proposed water mist system.
What should project teams do if an older specification refers to BS 9991 and water mist?
Start by checking which edition the specification was written against.
Projects can remain in design or procurement for a long time. Older specifications may have been written before the current edition was published.
If a specification contains both BS 9991 and water mist references, the design team should establish:
- Which edition of BS 9991 the project is using
- Why fire suppression is required within the fire strategy
- Whether sprinklers or water mist are actually being proposed
- Which standard supports the selected suppression system
- What fire-test and certification evidence supports any water mist proposal
- Who is responsible for accepting the technical route
Do not assume that changing one standard reference in the specification solves the entire issue.
The whole suppression route may need reviewing.
What standard should be considered for residential sprinkler systems?
For domestic and residential sprinkler systems, BS 9251 is commonly relevant.
BS 9251 covers sprinkler systems for domestic and residential occupancies and addresses matters including system categories, design, water supplies, installation, commissioning and maintenance.
On a residential scheme, BS 9991 and BS 9251 therefore perform different jobs.
BS 9991 relates to the wider fire-safety design of the residential building.
BS 9251 provides the specific sprinkler-system route where that standard applies.
For developers and consultants, the important thing is to connect the two correctly rather than treating them as interchangeable.
What standard should be considered for residential water mist systems?
Current residential water mist projects need to be considered against the relevant parts of the BS EN 14972 series.
The position changed significantly when BS 8458:2015 was withdrawn in July 2025.
For residential fire testing, BS EN 14972-17:2025 now provides the fire-test protocol for residential occupancies using automatic nozzle systems.
The wider BS EN 14972 framework also covers design, installation, inspection and maintenance.
This means project teams should avoid simply replacing the words “BS 8458” with “BS EN 14972” without reviewing the system evidence and intended application.
The specific test protocol, design requirements and system limitations still matter.
BS EN 14972 Water Mist Systems
Does the BS 9991 change mean water mist cannot be used on residential projects?
No.
It means water mist should be justified through the appropriate technical and approval route rather than relying on BS 9991 itself as the fixed firefighting recommendation.
A residential water mist proposal may still be considered where the system is appropriate for the building and supported by suitable evidence.
That assessment can involve the fire strategy, relevant BS EN 14972 requirements, product testing, system certification, Building Control review and other project stakeholders.
The important point is clarity.
The design team should be able to explain:
why water mist is being proposed, which standard supports it, what evidence supports the application and who has accepted the route.
How does this affect architects and specifiers?
Architects and consultants should check suppression references before issuing specifications for tender.
A specification written around an older version of BS 9991 could create uncertainty during procurement if it assumes water mist is covered by the current standard.
The specification should identify the required outcome and the technical route clearly enough for bidders to understand what they are pricing.
That may mean separating:
- The wider BS 9991 fire strategy
- Sprinkler requirements under the relevant sprinkler standard
- Any proposed water mist solution and its supporting standards
- Fire-test evidence
- Approval responsibilities
- Commissioning and handover requirements
This does not require pages of vague standards language.
It requires enough clarity for the contractor, consultant and approving body to understand the proposed route.
How does this affect main contractors?
For main contractors, the biggest risk is procurement ambiguity.
A tender package may say “water mist to BS 9991” while the fire strategy, drawings and specialist specification all say slightly different things.
That needs resolving before appointment.
Ask the design team to confirm which suppression system is required and which technical standard applies.
Then make sure the specialist contractor’s proposal matches that requirement.
Doing this before procurement is easier than discovering at commissioning stage that everyone thought somebody else had approved the technical route.
How does this affect residential developers?
Developers need enough certainty to protect the programme and avoid redesign.
The suppression system can influence plant space, water supply, risers, ceilings, apartment layouts and ongoing maintenance.
If the technical route changes after these areas have already been coordinated, the project can face unnecessary design work and cost.
Early suppression review is particularly useful on:
- Blocks of flats
- Apartment developments
- Supported-living schemes
- Care projects
- Housing-association developments
- Mixed residential buildings
For these projects, system selection should happen alongside the fire strategy rather than several stages after it.
Residential Fire Sprinkler & Water Mist Systems
What does BS 9991:2024 mean for flats and apartment blocks?
BS 9991 remains highly relevant to the wider fire-safety design of flats and apartment buildings.
The current version includes recommendations covering residential fire-safety design across areas such as escape, compartmentation, firefighting access, smoke control and fixed firefighting.
For projects in England, Approved Document B also contains sprinkler provisions for blocks of flats.
Current guidance states that blocks of flats with a top storey more than 11 metres above ground level should be fitted with a sprinkler system throughout the building in accordance with Appendix E.
The fire strategy should make clear which route applies to the project.
Fire Suppression for Flats & Apartments
Does BS 9991:2024 now include care homes?
Yes.
BSI states that residential care is included within the scope of BS 9991:2024.
That makes the revised standard particularly relevant to architects, care operators, developers and fire consultants planning new residential care projects.
Approved Document B has also been updated separately to provide for sprinklers in new care homes in England.
Those two sources should still be treated as separate parts of the compliance picture.
BS 9991 is a British Standard code of practice.
Approved Document B is statutory guidance supporting the Building Regulations in England.
The project team should establish how both apply to the specific development.
What should be checked at design stage?
A good residential suppression review should happen before the system is reduced to a single line in an M&E schedule.
Start with the fire strategy and drawings.
Then establish the building type, height, occupancy, proposed suppression system, water supply, plant space and approval route.
The design team should also confirm who is responsible for the system specification and who will provide the supporting technical evidence.
Where water mist is being proposed, the fire-test evidence should be reviewed against the actual application.
Where sprinklers are being proposed, the relevant sprinkler standard and system category should be established.
Residential Fire Suppression at Design Stage
Why does fire-test evidence matter more for water mist proposals?
Water mist systems rely heavily on tested performance for defined applications.
The evidence can include limits relating to:
- Occupancy
- Ceiling height
- Nozzle type
- Nozzle spacing
- Operating pressure
- Flow
- Room arrangement
- Fire scenarios
A residential water mist proposal should therefore be supported by evidence that matches the intended use of the building.
This is particularly important now that BS 9991:2024 itself no longer provides the fixed firefighting recommendation route for water mist.
The test evidence is part of explaining why the proposed system is suitable.
What should be included in the tender information?
The suppression tender package should give bidders enough technical information to price the same scope.
At minimum, it should make clear:
- The required suppression system
- The relevant sprinkler or water mist standard
- The areas requiring protection
- Design responsibility
- Water-supply and plant assumptions
- Required fire-test or certification evidence
- Commissioning and handover requirements
- Approval and coordination responsibilities
Clear tender information makes contractor proposals easier to compare.
What if the project has already been designed to an older standard?
Do not automatically redesign everything.
First establish the project status.
Check:
- When the fire strategy was prepared
- Which standards are named
- Whether approvals have already been given
- What system has been specified
- Whether procurement has started
- Whether installation has started
- What product evidence is available
- Whether there are transitional or project-specific considerations
The relevant consultant, Building Control body and specialist contractor may need to review the position together.
The fact that a newer edition exists does not, by itself, tell you how every live project should be handled.
What about existing residential buildings?
Existing systems should be considered in the context in which they were designed and installed.
A water mist system originally designed to an older standard should not automatically be described as unsuitable simply because the standards landscape has changed.
Its current position depends on factors including:
- Original design basis
- Certification and fire-test evidence
- Commissioning records
- Alterations since installation
- Current building use
- Maintenance history
- Condition of the system
If the system or building has changed, further technical review may be appropriate.
Fire Suppression System Maintenance
What information should you send NPHS?
For an early review, send your drawings and fire strategy.
It is also useful to provide any consultant specification, Building Control comments and information showing which suppression system has already been proposed.
If the project is already at tender stage, send the suppression specification as well.
NPHS can review the practical fire suppression scope and identify where the proposed system, standards references or project information need clarification.
Need help reviewing a BS 9991 residential project?
NPHS supports architects, developers, main contractors, fire consultants, M&E consultants, housing providers and care-sector project teams with residential fire suppression.
We can review:
- Project drawings
- Fire strategy requirements
- Sprinkler or water mist options
- Standards references
- Water supply
- Plant requirements
- Installation planning
- Commissioning
- Handover documentation
- Planned maintenance
Where water mist is proposed, we can also help identify the technical information needed to support the project-specific route.
Frequently asked questions
What is BS 9991:2024?
BS 9991:2024 is the current British Standard code of practice for fire safety in the design, management and use of residential buildings. It covers a wide range of residential buildings, including dwellings, blocks of flats, residential accommodation, specialised housing and care homes.
Does BS 9991:2024 cover water mist systems?
The current edition refers solely to sprinkler systems within its fixed firefighting recommendations. Where water mist is proposed, the project team should establish a separate technical route using the relevant water mist standard, supporting fire-test evidence, fire strategy and approval process.
What changed for sprinklers in BS 9991:2024?
BS 9991:2024 revised several areas of sprinkler guidance as part of the wider update to residential fire safety. BSI also states that the standard’s fixed firefighting recommendations now refer solely to sprinkler systems rather than other suppression technologies.
Can water mist still be used on residential projects?
Water mist can still be considered where it is suitable for the building and supported by the appropriate standards, test evidence and project-specific approval route. It should not simply be presented as though BS 9991:2024 itself provides the sprinkler-equivalent route.
Can NPHS review an older specification that refers to BS 9991 and water mist?
Yes. NPHS can review the drawings, fire strategy and suppression specification to identify the system being proposed, the standards referenced and the practical technical information that may need clarification before procurement or installation.
Need help reviewing a BS 9991 residential project?
NPHS supports architects, developers, main contractors, fire consultants, M&E consultants, housing providers and care-sector project teams with residential fire suppression.
Send us the latest drawings, fire strategy and suppression specification. We can review the proposed system route, relevant standards, water supply, plant requirements, installation planning, commissioning and maintenance considerations.
Send your drawings or fire strategy for review