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BS 9999 Fire Alarm Guidance: The Full Decision Method for Fire Risk Assessors

This is the full, clause-by-clause version of our guidance on determining fire detection and alarm provision in non-domestic premises using BS 9999:2017, written for fire risk assessors and others who want a reliable, repeatable decision-making method. Citations below give the exact clause, table and PDF page of the standard (“PDF p.” refers to the page of the PDF edition; the printed page number is typically 16 lower, e.g. Table 7 is on printed page 63, PDF p.79). Before applying this guidance, get access to the standard itself: buy BS 9999:2017 from the BSI Knowledge shop, or if you are a member of the Institute of Fire Safety Managers (IFSM), you can access British Standards through the Institute’s standards arrangement with BSI Knowledge.

Important caveat before you start. BS 9999 itself states that its Clause 5 risk assessment “is not designed to satisfy the fire risk assessment requirements of any fire safety-related legislation” (Clause 5, NOTE 2, PDF p.44). The legal duty in England and Wales to assess the need for fire detection and warning arises from the Regulatory Reform (Fire Safety) Order 2005 (Articles 9 and 13) and its Scottish and Northern Irish equivalents. BS 9999 is guidance you may use to inform your professional judgement; it is not itself a legal requirement, and the government-published fire risk assessment guides remain a legitimate benchmark for many existing premises. Nothing below should be recorded in a report as a legal requirement unless the legislation itself supports it.

Table of Contents

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1. Scope and limitations of BS 9999

When it applies. BS 9999 covers the design, management and use of most non-domestic buildings and “can be used as a tool for assessing existing buildings, although fundamental change in line with its recommendations might be limited or not practicable” (Clause 1, PDF p.23). That sentence matters for existing premises: you are using BS 9999 as a benchmarking framework, not as a retrospective compliance test.

When it does not apply. Clause 1 (PDF p.23) excludes: dwellings, self-contained flats and maisonettes; residential accommodation blocks with bedrooms and kitchen/sanitary facilities within a fire compartment; and specialised housing (all covered by BS 9991). It is not applicable to HMOs or to buildings where occupants receive medical care (occupancy characteristic D — hospitals and residential care — is explicitly outside scope, Table 2 footnote B, PDF p.46), and it has only limited applicability to specialist buildings such as areas of lawful detention. For those premises use BS 9991, HTM 05-02/FSA guidance, LACORS/housing guidance or the sector-specific government guides as appropriate.

Do not cherry-pick. The Introduction warns: “When evaluating an existing building, e.g. when carrying out a fire risk assessment, it is important to review all general fire precautions and not to use parts of the standard in isolation” (Introduction, PDF p.13). Table 7 is one component of a coordinated package that also assumes the travel distances, exit widths, management levels and structural provisions that flow from the same risk profile. If the building does not deliver the rest of that package (e.g. travel distances exceed the Table 11 limits for the risk profile), the alarm provision may need to compensate — and vice versa (see Clause 18, PDF pp.113–118, where enhanced detection is expressly used to offset extended travel distances).

Life safety first, property second. The primary objective is life safety; property and business protection is a secondary objective addressed by normative Annex A (Clause 0.1, PDF p.19; Annex A, PDF p.271).

2. Fire alarm decision process

A repeatable sequence for use on site:

  1. Confirm BS 9999 is the right benchmark (Section 1 above). If occupants sleep in individual dwellings, receive care, or the premises is an HMO, stop and use the appropriate guidance instead.
  2. Divide the building into assessment areas. “A separate risk profile should be assigned to each part of a building, including ancillary accommodation, and in mixed-use buildings an appropriate profile derived for differing occupancy types” (Clause 5, PDF p.44; Clause 6.4 commentary, PDF p.48).
  3. Establish the occupancy characteristic for each area — awake/asleep, familiar/unfamiliar — using Table 2 (Clause 6.2, PDF p.46).
  4. Establish the fire growth rate (1 slow to 4 ultra-fast) using Table 3, with justification recorded: “Where available, justification should be provided in selecting a specific fire growth rate” (Clause 6.3, PDF p.46–47).
  5. Combine the two into the risk profile using Table 4 (Clause 6.4, PDF p.48). Check whether sprinklers legitimately reduce the fire growth rate by one level (Clause 6.5, PDF p.49). Note the unacceptable combinations (A4, B4, C4 without suppression; C3 only with special precautions — Table 4 footnotes, PDF p.48).
  6. Read off the minimum detection and alarm category from Table 7 (Clause 15.2, PDF p.79). This is the floor, not the answer.
  7. Apply the BS 9999 uplift triggers that override or supplement Table 7 (Clause 15.2 notes, PDF p.80): phased/staged/zoned evacuation or primary/special-needs school → at least L3 with the evacuation strategy in mind; multi-occupancy → common system appropriate to the individual risks; unfamiliar occupants → consider voice and/or visual alarm (Table 7 footnote B and 18.2); noisy areas or people who may not hear the alarm → visual alarm devices.
  8. Apply premises-specific judgement (Section 5 below): sleeping risk, lone working, unoccupied/concealed areas, inner rooms, high-bay storage, dependence of other fire safety systems on detection, management quality, and any property/business-continuity objectives (Annex A).
  9. Sense-check against the whole package. Does the recommended provision sit consistently with travel distances, compartmentation, evacuation strategy and management level actually found on site? (Introduction, PDF p.13; Clause 15.1, PDF p.78.)
  10. Record the conclusion with reasons (Section 8 below), and state that detailed design, installation, commissioning and maintenance are matters for a competent designer working to BS 5839-1 (Table 7 NOTE, PDF p.79) — and BS 5839-8 for voice alarms (Clause 15.3, PDF p.80).

3. The BS 9999 risk-profile method (Tables 2, 3, 4 and 7)

Clause 5 — assessing risk (PDF p.44). The assessment considers the likelihood of fire, its anticipated severity and spread, the structure’s ability to resist fire and smoke spread, the consequential danger to people, and any property/business/environmental objectives. Table 1 (PDF p.45) lists “early fire warning by an automatic detection and warning system” as one of the basic factors, noting it “can lead to ‘first aid’ or fire and rescue service fire-fighting in the early stages of fire development”.

Table 2 — occupancy characteristic (Clause 6.2, PDF p.46). Determined “principally … according to whether the occupants are familiar or unfamiliar with the building and whether they are likely to be awake or asleep”:

  • A — awake and familiar (offices, industrial premises)
  • B — awake and unfamiliar (shops, exhibitions, museums, leisure/assembly)
  • C — likely to be asleep: Ci long-term individual (flats — BS 9991 territory), Cii long-term managed (halls of residence, boarding-school sleeping areas), Ciii short-term (hotels)
  • D — receiving medical care (outside scope)

Use the most vulnerable realistic occupancy, not the typical one — e.g. a trade counter within a factory brings characteristic B people into an A building; assess those areas separately (Clause 6.4 commentary, PDF p.48).

Table 3 — fire growth rate (Clause 6.3, PDF pp.46–47). Category 1 slow (limited fire load — foyers, concourses), 2 medium (offices, classrooms, lounges), 3 fast (shop sales areas, workshops, factories, small storage, stacked combustibles), 4 ultra-fast (warehousing as a worst-case assumption, high-racked storage, flammable liquids/gases). Key points for assessors: an assessment “should be carried out for every premise”, especially warehouses where growth rate “can vary considerably” (NOTE 1); fire load density and growth rate are not the same thing (NOTE 2); areas of high fire risk are generally at least category 3, but effective localised suppression can allow treatment as medium (NOTE 3); category 4 “is unacceptable unless a sprinkler system is installed” (footnote G); and warehouse categorisation may be moderated by what is actually stored and how (footnote H).

Table 4 — risk profile (Clause 6.4, PDF p.48). Simply combines the two: A1–A4, B1–B4, C1–C4. A4, B4 and C4 are unacceptable within BS 9999 unless suppression reduces the growth rate (footnote A); C3 is “unacceptable under many circumstances unless special precautions are taken” (footnote C). Where different profiles rely on a common measure, the most conservative governs (Clause 6.4, PDF p.48). Sprinklers to BS EN 12845 (new) or BS 5306-2 (existing) reduce the fire growth rate by one level in sprinklered areas (Clause 6.5, PDF p.49).

Table 7 — minimum detection and alarm level (Clause 15.2, PDF p.79):

Risk profileMinimum system
A1, A2M
A3L2
B1, B2M (voice/visual can reduce evacuation time — footnote B)
B3L2
Ci1, Ci2AFD in individual units
Cii1, Cii2L2
Ciii1–Ciii3L1 (Cii3 also L1; Ci3 L3)
A4, B4, C4Not applicable — profile unacceptable

The table’s NOTE states that “Type M, L3, L2 and L1 systems are defined in BS 5839-1:2013” — BS 9999 deliberately does not define detector coverage, siting, sound levels or zoning; those are BS 5839-1 design matters.

How they work together. Table 7 embodies two simple principles stated in the notes to 15.2 (PDF p.80): “Generally, the minimum requirement for premises is an electrical system in accordance with the recommendations applicable to a Type M as described in BS 5839-1:2013. Premises with a higher fire growth rate usually require a more sophisticated system. In some low-risk premises, an alternative means of giving warning in the event of fire might be more appropriate.” Awake occupants with slow/medium fire growth can generally rely on discovering the fire themselves and raising the alarm manually; fast fire growth (category 3) buys less time, so automatic detection (L2) becomes the minimum; sleeping occupants cannot discover fire, so automatic detection extending into their sleeping areas (L2/L1) is the minimum. Clause 15.1 (PDF p.78) frames all of this as part of the “minimum package of fire protection” — detection and alarm sit alongside escape routes, lighting, signage and management, and are assessed together, not in isolation.

4. Fire alarm categories (defined in BS 5839-1; summarised in plain English)

BS 9999 uses these labels but leaves their content to BS 5839-1:2013 (Table 7 NOTE, PDF p.79). In outline:

CategoryWhat it generally providesTypical circumstances
MManual system only — call points and sounders operated by people; no automatic detection. Relies on occupants discovering the fire.Simple premises where occupants are awake, familiar or supervised, and fire growth is slow/medium (A1, A2, B1, B2).
L3M plus automatic detection on escape routes and in rooms opening onto them, so routes are warned before they become impassable.Phased/staged/zoned evacuation; primary and special-needs schools; premises where warning must precede smoke-logging of routes.
L2L3 plus automatic detection in defined rooms/areas of high fire hazard or high risk to occupants.Fast fire growth profiles (A3, B3); managed sleeping risk (Cii1, Cii2); specific hazard rooms identified by the assessment.
L1Automatic detection throughout virtually the whole building — earliest practicable warning.Short-term sleeping risk (hotels, Ciii); highest life-risk combinations (Cii3).
Voice alarm (BS 5839-8)Spoken evacuation messages instead of/as well as sounders; types V1–V5 by degree of manual control (Clause 15.3, PDF p.80).Occupants unfamiliar with the building; phased evacuation (required with ≥L3 by Clause 12.2.2, PDF p.71).
Visual alarm devices (BS EN 54-23)Flashing beacons, pagers, vibrating devices supplementing audible warning.Noisy areas, hearing protection zones, people who are Deaf or hard of hearing (15.2 NOTE 2, PDF p.80; 45.4, PDF p.262).

(L4 and L5 exist in BS 5839-1 but are not called up by Table 7; P categories are covered in Section 5 below.)

The distinctions you must keep separate in your report:

  1. A means of raising the alarm — the basic legal need for warning of fire to be given (however achieved).
  2. A manual fire alarm system (Category M) — an electrical system of call points and sounders, which BS 9999 treats as the general minimum (15.2 NOTE 1, PDF p.80).
  3. Automatic fire detection — detectors that find the fire without human intervention.
  4. The extent of AFD — escape routes only (L3), plus high-risk rooms (L2), or throughout (L1); this is where L-categories differ.
  5. The method of warning occupants — sounders, voice messages, or visual/tactile devices; this can vary independently of the detection category.

A recommendation should address each element explicitly: detection (whether and how far), initiation (manual call points), and warning (audible/voice/visual).

5. Factors that may increase the minimum provision

Table 7 gives the floor for the risk profile. BS 9999 itself identifies the following uplift triggers; the remainder are matters of assessor judgement consistent with the standard’s principles and, for detailed application, BS 5839-1.

Triggers stated in BS 9999:

  • Phased, staged or zoned evacuation: “As a minimum, an L3 fire detection and fire alarm system should be installed where a phased, staged or zoned evacuation is proposed, and for primary or special needs schools” (15.2, PDF p.80). For buildings designed for phased evacuation, Clause 12.2.2 (PDF p.71) additionally expects sprinklers, at least L3 incorporating a voice alarm to BS 5839-8, and an emergency voice communication system to BS 5839-9.
  • Multi-occupied buildings: “Multiple occupancy premises should be provided with a common fire detection and fire alarm system appropriate to the individual risks” (15.2, PDF p.80). Independent, uncoordinated systems in a shared building are a finding, not a footnote — the highest individual risk sets the standard for the common system.
  • Unfamiliar occupants: for B profiles “the provision of a voice and/or visual alarm system can help reduce evacuation time” (Table 7 footnote B, PDF p.79). The 18.2 commentary (PDF p.118) explains why: shoppers “respond much more slowly and might not begin evacuation until requested to do so by the staff”, and where AFD is already required for a B building, “incorporating a voice alarm … provides a clear benefit over non-voice sounders”.
  • Noisy environments / people who may not hear the alarm: “In areas with noisy environments or where people might otherwise have difficulty in hearing the fire alarm, visual alarm devices (flashing warning beacons) can be useful” (15.2 NOTE 2, PDF p.80). For people who are Deaf or hard of hearing, “visual alarm devices … vibrating pagers or pillows, and similar alert devices should be provided … backed up by an integrated fire management plan” with PEEPs and buddy systems (45.4, PDF p.262).
  • Inner rooms: one of the acceptable arrangements is an automatic smoke detector in the access room giving an immediately audible alarm in the inner room — or an immediate visual alarm to BS EN 54-23 “if the ambient noise levels are so great as to make an alarm inaudible” (16.3.4, PDF pp.92–93). Where you rely on this arrangement, localised detection becomes a life-safety necessity even in an otherwise Category M building.
  • Detection as the initiator of other systems: the 15.2 commentary (PDF p.79) notes AFD can be used to close down ventilation/air-conditioning, operate suppression and smoke control, release hold-open door devices and shutters, and activate ventilation. If any such system exists on site, detection coverage and cause-and-effect must be adequate to operate it — check what actually triggers each device.
  • Travel-distance trade-offs: where extended travel distances or reduced widths rely on the 15% variation for AFD or voice alarm under 18.2 (PDF p.118), that detection is load-bearing: it cannot be downgraded without re-assessing the escape geometry. Conversely, “where detection and warning systems and/or voice alarms are required as part of the minimum package … no variation is permitted” (18.2 NOTE, PDF p.118) — you cannot count the same system twice.
  • High fire growth / storage: category 3 growth already pulls A/B profiles to L2 via Table 7; warehousing defaults to category 4 as “a worst case assumption” (Table 3 footnote H, PDF p.47), which is unacceptable without sprinklers (footnote G) — so a high-bay combustible warehouse without suppression sits outside the standard’s normal envelope and demands a bespoke package, typically including early automatic detection, suppression, and insurer involvement.

Matters of assessor judgement (consistent with Clause 5 factors, PDF p.44, and BS 5839-1 principles):

  • Size, layout and complexity; quick discovery. In a small, open, continuously occupied space a fire will be seen or smelt almost immediately and a shout or manual system suffices. As floors, walls, storeys and remoteness increase, the probability of early human discovery falls and the case for AFD strengthens.
  • Normally unoccupied, remote or concealed spaces (basements, plant rooms, stores, roof voids, service risers) can allow a fire to develop undetected until it threatens escape routes — a common justification for extending detection beyond the Table 7 minimum, particularly where such spaces adjoin the means of escape.
  • Lone workers and sleeping occupants. A lone worker cannot rely on others to discover fire or raise the alarm; any sleeping accommodation moves the premises into C profiles (or out of BS 9999 scope entirely) and automatic detection becomes non-negotiable.
  • Disabled occupants — coordinate the alarm recommendation with PEEPs, refuges and evacuation-lift arrangements (Clause 45, PDF pp.260–266).
  • Compartmentation, protected routes, dead ends. Where escape depends on a single direction of travel, long dead-end corridors, or doubtful compartmentation, earlier warning (L3-type coverage of the route) compensates for the reduced margin.
  • Management adequacy. Category M and any staged/voice arrangement assume trained people who will operate call points and manage evacuation (15.3 NOTE 2, PDF p.80, warns against manual control where training cannot be guaranteed). Weak management is itself a reason to prefer automatic detection and automatic (V1-type) messaging.
  • Property protection and business continuity. Annex A (normative, PDF pp.271–275) requires the potential for property and business loss to be assessed where that is an objective, identifying single points of failure and additional protection beyond life-safety provision. BS 9999 does not itself define P1/P2 — those are the property-protection categories of BS 5839-1 (P1 = detection throughout; P2 = detection in defined parts). Where the client or insurer has property/continuity objectives, recommend that a P-category be specified under BS 5839-1 in consultation with insurers (Annex A commentary notes insurers commonly apply the FPA/LPC guides, PDF p.271), typically combined with remote alarm-receiving-centre signalling. Present this separately from the life-safety recommendation.

When might a non-electrical means (shout, gong, air horn) be defensible? BS 9999 opens the door only slightly: “In some low-risk premises, an alternative means of giving warning in the event of fire might be more appropriate” (15.2 NOTE 1, PDF p.80). To rely on this you should be able to evidence all of the following: a single, small, simple layout (typically single-storey, open-plan or few rooms); a slow/medium fire growth rate with recorded justification (Clause 6.3, PDF p.46); occupants who are awake, few in number, familiar with the building and within earshot of each other everywhere the device can be heard (test it); no sleeping, no lone working out of earshot, no members of the public in significant numbers, no inner rooms relying on 16.3.4 detection, no unoccupied areas where fire could develop unseen, and no other fire safety systems dependent on an alarm signal. Record the audibility check and the reasoning. Small size alone is not sufficient — the conclusion must rest on the whole risk picture, and the government FRA guides for the premises type should support it.

6. Site inspection checklist

Occupancy and use

  • Who is in each part of the building, at what times — including cleaners, contractors, out-of-hours and lone workers?
  • Are any occupants asleep, ever (including informal napping/overnight security)? If yes in dwellings/care settings — is BS 9999 the right benchmark at all?
  • Are members of the public present? In what numbers, and how dependent are they on staff direction?
  • Anyone with hearing, sight, mobility or cognitive impairments? Are PEEPs in place (45.7)? Would they hear the existing alarm everywhere (including WCs, plant areas)?
  • Is hearing protection worn anywhere? Ambient noise levels in production areas?

Fire load and growth

  • What is stored/processed, in what quantities and configuration — stacked, racked, high-bay? Flammable liquids/gases? (Table 3 categories and footnotes, PDF p.47.)
  • Any high-fire-risk rooms (13.4) — kitchens, spray areas, charging areas, boiler/plant rooms?
  • Sprinklers or localised suppression fitted? To what standard, and maintained? (6.5, PDF p.49.)

Building and escape

  • Storeys, floor areas, dead ends, single-direction travel; measured worst-case travel distances against the Table 11 values for the risk profile.
  • Inner rooms — which of the three 16.3.4 arrangements applies? If detection, does it work and alarm audibly/visibly in the inner room?
  • Normally unoccupied, remote or concealed spaces adjoining escape routes; condition of compartmentation to those spaces.
  • Do any relaxations (extended travel, narrowed stairs) appear to rely on AFD/voice alarm under 18.2? If so, treat that system as essential.

Existing alarm arrangements

  • What exists: shout/gong, Category M, AFD? Where are detectors actually located (routes only, hazard rooms, throughout)?
  • Can the alarm be raised, and heard, from every part of the building? Test evidence?
  • What does the alarm trigger — door releases, shutter drops, ventilation shutdown, smoke control, suppression, ARC signalling? Does cause-and-effect match the evacuation strategy?
  • Evacuation strategy: simultaneous, phased, staged, zoned? If not simultaneous — is there at least L3 with voice alarm and EVC (12.2.2, PDF p.71; 15.2, PDF p.80)?
  • Multi-occupancy: is there a common system? Who manages it, and does it reflect the highest individual risk?

Management

  • Servicing/maintenance records (the design standard for these is BS 5839-1); weekly testing; false-alarm history.
  • Staff training, fire marshals, evacuation drills; who operates any manual voice-alarm controls (15.3 NOTE 2)?
  • Client objectives beyond life safety — property, continuity, insurer requirements (Annex A)?

7. Worked examples

7.1 Small single-storey office (8 staff, open plan, no public, no sleeping). Table 2: characteristic A (awake, familiar — “office” is the given example, PDF p.46). Table 3: category 2 medium (“offices”, PDF p.47). Table 4: A2. Table 7 minimum: Category M (PDF p.79). Uplift check: no phased evacuation, no unfamiliar occupants, small simple layout, fire likely discovered quickly. If genuinely all staff are always within earshot, 15.2 NOTE 1’s “alternative means” could be considered, but any lone working, inner offices or a server/store room where fire could start unseen argues for retaining M, possibly with limited AFD to those rooms. Conclusion: Category M electrical system; extent of any supplementary detection to be determined under BS 5839-1.

7.2 Manufacturing workshop. Characteristic A (industrial, PDF p.46). Table 3: category 3 fast (“workshops, factories”, PDF p.47) — unless the process and storage genuinely support category 2, with justification recorded. Table 4: A3. Table 7 minimum: L2 (PDF p.79) — automatic detection covering escape routes, rooms opening onto them and the identified hazard areas. Uplifts: noisy machinery/hearing protection → visual alarm devices (15.2 NOTE 2, PDF p.80); detection in any normally unoccupied stores/plant adjoining the routes; check any localised suppression that might justify treating a hazard area as medium risk (6.3 NOTE 3, PDF p.46). Extent of L2 coverage is a BS 5839-1 design decision agreed between designer and responsible person.

7.3 Warehouse with high-bay combustible storage. Characteristic A. Table 3: high-racked storage → category 4 ultra-fast (PDF p.47), “unacceptable unless a sprinkler system is installed” (footnote G). If sprinklered to BS EN 12845/BS 5306-2, growth reduces one level (6.5, PDF p.49) → A3 → Table 7 minimum L2. If unsprinklered, the premises falls outside BS 9999’s acceptable envelope: record this as a significant finding; the package (suppression, detection, travel distances, management) needs specialist/fire-engineering input, and insurers will almost certainly have property-protection expectations (Annex A, PDF p.271) — consider a P1 system with ARC signalling under BS 5839-1 as a separate property recommendation. Do not present Table 7 output as adequate here.

7.4 Shop open to the public. Characteristic B (awake, unfamiliar — “shops”, PDF p.46). Table 3: sales areas → category 3 fast (footnote F allows adjustment for what is actually displayed, PDF p.47). Table 4: B3 (or B2 for a genuinely low-fire-load unit, with justification). Table 7: B3 → L2; B2 → M (PDF p.79). Uplifts: footnote B and 18.2 commentary (PDF pp.79, 118) — the public respond slowly and may await staff direction, so where AFD is required a voice alarm gives “a clear benefit over non-voice sounders”; in a larger store consider staff-alarm/staged arrangements (which then require at least L3, 15.2, PDF p.80) and visual devices in noisy or WC areas. Sprinklered shopping-complex units: see Annex E and 6.5.

7.5 Multi-occupied commercial building (e.g. offices over ground-floor retail, shared stair). Assess each demise separately (Clause 5, PDF p.44): retail unit B3 → L2; office floors A2 → M. Then apply 15.2 (PDF p.80): “Multiple occupancy premises should be provided with a common fire detection and fire alarm system appropriate to the individual risks” — one interlinked system, specified to the most onerous need, warning all occupancies (a fire in the shop must alert the offices, whose only escape route may pass the shop). The shared escape route is a common measure, so the most conservative profile governs it (6.4, PDF p.48). Detection to normally unoccupied common parts and any concealed service spaces on the shared route is usually justified. If any evacuation other than simultaneous is proposed, at least L3 with voice alarm applies (15.2/12.2.2). Landlord/tenant responsibility for the common system is a management finding in its own right.

8. Recording the conclusion

Example paragraph for a fire risk assessment report (workshop example):

“The premises is a single-occupancy manufacturing workshop. Occupants are awake and familiar with the building (BS 9999:2017 Table 2, occupancy characteristic A). Having regard to the stacked combustible stock and the processes observed, the likely fire growth rate is assessed as category 3, fast (Table 3), giving a risk profile of A3 (Table 4). For this profile, Table 7 of BS 9999:2017 indicates a Category L2 automatic fire detection and alarm system (as defined in BS 5839-1:2013) as the minimum level of provision. In addition, because machinery noise and the use of hearing protection in the press shop could prevent the alarm being heard, visual alarm devices are recommended in those areas (BS 9999:2017, 15.2 NOTE 2 and 45.4), and detection should extend to the normally unoccupied stores adjoining the escape corridor, where a fire could develop undetected. The existing installation is a Category M manual system and therefore falls below this benchmark. This recommendation reflects the overall package of fire precautions found on site — including the travel distances and the standard of management observed — and is not based on Table 7 in isolation. The category, extent of coverage, siting of detectors and call points, audibility and visual-warning provision should be confirmed by a competent fire alarm designer against the current edition of BS 5839-1, and the system thereafter serviced and maintained in accordance with that standard. This is a recommendation of good practice made to assist the responsible person in meeting the general duty under Article 13 of the Regulatory Reform (Fire Safety) Order 2005 to provide appropriate means of detecting fire and giving warning; BS 9999 and BS 5839-1 are not themselves statutory requirements.”

Adapt the same skeleton for any premises: occupancy characteristic → fire growth rate (with justification) → risk profile → Table 7 minimum → premises-specific uplifts (each with its reason) → comparison with existing provision → whole-package statement → referral to BS 5839-1 for design detail → legal framing. Where property protection or business continuity is a client objective, add a separate, clearly labelled recommendation for a P-category system under BS 5839-1, developed with the insurer (BS 9999:2017 Annex A, PDF pp.271–275).

Prepared with reference to BS 9999:2017 (© BSI). PDF page numbers refer to the PDF edition of the standard. Detailed design, installation, commissioning and maintenance of fire detection and alarm systems, including the precise meaning and application of Categories M, L1–L5 and P1–P2, are matters for the current edition of BS 5839-1 (BS 9999:2017 cites the 2013 edition; check which edition applies at the date of assessment) and BS 5839-8/-9 for voice alarm and EVC systems, applied by a competent fire alarm designer. Nothing here constitutes legal advice.

Sources and further reading

BS 9999:2017 Fire safety in the design, management and use of buildings – Code of practice – BSI Knowledge
BS 5839-1:2025 Fire detection and fire alarm systems for buildings (non-domestic premises) – Code of practice – BSI Knowledge
A guide to the changes in fire alarm system standard BS 5839-1 – BSI
Regulatory Reform (Fire Safety) Order 2005 – legislation.gov.uk
Fire safety in the workplace – GOV.UK
Fire safety legislation and guidance for those with legal duties – GOV.UK
The Institute of Fire Safety Managers (IFSM) – membership, fire risk assessor registers and standards access

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