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It has now been a year since BS 5839-1:2025 came into force on 30 April 2025, replacing the 2017 edition and introducing the most significant overhaul of fire detection and alarm guidance in nearly a decade.
In the twelve months since, the conversations I have been having with building owners, facilities managers, and responsible persons have shifted from “what does this mean?” to “what do we actually need to do about it?”
This article is aimed at answering that second question honestly. Because while much of the commentary at the time of publication focused on the technical changes, the more useful question a year on is a practical one: if you are responsible for a non-domestic building in 2026, where do you stand?
Why the BS 5839-1:2025 revision mattered
The 2025 update was not a routine refresh. It came in the wake of the Grenfell Tower tragedy and the wave of fire safety legislation that followed, including the Building Safety Act 2022. The revision was brought forward ahead of schedule by BSI technical committee FSH/12/1 specifically to address safety improvements in the wake of fatal fire incidents. That context matters, because it shapes how the changes should be understood, not as bureaucratic updates, but as responses to real failures.
The ban on heat detectors in sleeping areas
This is arguably the most significant practical change, and the one that will affect the widest range of buildings over time. Category L2 has been revised to define rooms where people sleep (hotel bedrooms, student accommodation, care home rooms, supported housing etc) as high-risk, meaning heat detectors are no longer permitted in those spaces. Smoke, multi-sensor, or carbon monoxide fire detectors are now required.
The standard is clear that this does not require retrospective immediate replacement in existing buildings. If your current system was installed to the 2017 edition, you are not automatically non-compliant. However, any extension, modification, or new installation must follow the 2025 standard, and the responsible person should treat any upcoming system work as the natural trigger to bring affected areas up to date.
Stairway lobbies, previously considered low-risk and often excluded, must now also have automatic detection. This is a meaningful change for any multi-storey building with existing coverage gaps.
We have seen this play out on the ground. Our engineers recently completed a panel replacement and recommissioning project across several student accommodation buildings. During that work, they identified a number of bedrooms still fitted with heat detectors – a legacy of installations predating the 2025 standard. Those were flagged, and the devices were replaced with multi-sensor detectors to bring the affected rooms into compliance. It is a straightforward fix when caught at the right moment, but it underlines why system modification work is the natural trigger to review detector types throughout a building. Smoke inhalation, not heat or flames, is typically the cause of death in fire incidents involving sleeping occupants, which is precisely why the standard has drawn a firm line here.
“A lot of specifications we are receiving still do not reference the 2025 version of the regulations. However, early engagement with the client and/or consultants is slowly turning this around.” Sam Burgess, Evolution Life Safety Systems”
That observation reflects something we are seeing consistently across our project pipeline. The standard has been in force for a year, but the specification community has not fully caught up. If you are commissioning a new fire alarm system or extension, it is worth checking at the earliest stage that your specification references BS 5839-1:2025 rather than the withdrawn 2017 edition. An early conversation with your fire alarm contractor or consultant, before design is locked, will save complications at commissioning.
The PSTN switchover and transmission timing
One of the more time-sensitive issues the 2025 revision addresses is the impending switch-off of the public switched telephone network (PSTN) in 2027. Many fire alarm systems still use PSTN-based transmission equipment to signal alarm receiving centres (ARCs). When the PSTN is switched off, those transmission paths will no longer work.
BS 5839-1:2025 now sets specific timing requirements for alarm transmission equipment: alarm signals must reach the ARC within 90 seconds for life safety systems, and fault signals must be detected within three minutes. These requirements are designed to ensure that the move to IP-based transmission, which will be mandatory in practice after the PSTN goes, does not result in degraded performance.
If your building uses monitored fire alarm signalling and you have not already reviewed whether your transmission equipment is IP-compatible, this is urgent. 2027 sounds distant; system procurement and installation lead times mean it is not.
Cybersecurity requirements for remote access
For the first time, BS 5839-1:2025 introduces formal cybersecurity requirements for fire alarm systems that incorporate remote access. The standard now requires that any remote servicing provision must have appropriate cybersecurity measures in place including protection of remote access pathways.
This reflects a broader shift in how fire and security systems are being managed. Remote monitoring and remote servicing capability is increasingly common, and the attack surface that creates is real. The 2025 standard’s approach aligns with the wider trajectory of cyber-physical security, recognising that a fire alarm system connected to a network is not just a life safety asset, but a potential entry point if not properly secured.
For responsible persons and facilities managers, the practical implication is straightforward: if your fire alarm system supports remote access, ask your maintenance contractor to confirm that the cybersecurity provisions required by the 2025 standard are in place. This should be documented.
Documentation, logbooks, and prohibited variations
The 2025 standard places significantly greater emphasis on documentation throughout the system lifecycle, and introduces a category of “unacceptable variations” – deviations from the standard’s recommendations that are now explicitly prohibited.
Among the prohibited variations: omitting a zone plan in a multi-zone building with sleeping accommodation, or failing to provide ARC signalling in residential care homes. These are no longer judgement calls.
All variations from the standard (where they are permitted) must now be recorded in the system logbook, along with the risk assessment justification. Cause-and-effect matrices must be provided at handover. The logbook format has been updated, and the standard is explicit that it must be maintained and available.
The practical upshot: if your building’s fire alarm documentation is out of date, incomplete, or has never been properly assembled, the 2025 revision has made that a more significant compliance risk than before.
Visual alarm devices and inclusivity
The 2025 edition places greater emphasis on visual alarm devices (VADs) – flashing beacons and other visual alerting methods for people who are deaf or hard of hearing. The standard now requires that where the fire risk assessment identifies the likely presence of such individuals, the system design must account for this, including appropriate VAD provision.
This is not a new concept, but the 2025 revision has sharpened the obligation. For buildings with regular occupancy by the public, or with sleeping accommodation, this should be reviewed as part of any system audit.
Five questions every responsible person should be asking in 2026
If your maintenance regime was established against the 2017 edition, it may need updating, particularly around documentation requirements, logbook maintenance, and service interval recording.
If your system signals to an ARC via PSTN, the 2027 switch-off is a firm deadline. Start the conversation with your contractor now.
If your building has bedrooms (i.e. care home, hotel, student accommodation) and your current system uses heat detectors in those areas, understand when and how you will address this at the next system modification.
Zone plans, logbooks, design certificates, cause-and-effect matrices, and records of any variations all need to be in place and available.
If you are procuring a new system or extension, make sure your consultant or contractor is designing to BS 5839-1:2025, not the withdrawn 2017 edition.
What the BS 5839-1:2025 revision means in practice
The anniversary of BS 5839-1:2025 is a useful prompt to take stock. For most buildings where systems are maintained by a competent contractor and documentation is in order, the transition will be manageable, particularly because the standard does not mandate retrospective upgrading of compliant existing systems.
But the combination of the PSTN deadline, the sleeping area requirements on future work, the new cybersecurity provisions, and the tightened documentation obligations means there is meaningful action required across most estates at some point in the near future. The time to plan for that is now, not when a system modification forces the issue.
At Evolution Life Safety Systems, we work with building owners, facilities managers, and responsible persons to navigate exactly these kinds of transitions – from initial compliance review through to design, installation, and ongoing maintenance. If you would like to understand how BS 5839-1:2025 affects your specific estate, we would be glad to help.
Speak to our Life Safety Systems team about a BS 5839-1:2025 compliance review for your building.
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Sam Burgess is one of our account managers responsible for system sales in the Life Safety Systems division at Evolution, part of Evolution Security Group. With over 20 years of experience in fire detection and alarm systems across commercial, healthcare, education, and residential care sectors, Sam works with clients across the UK to design, install, and maintain systems that meet both regulatory requirements and the practical realities of building management.