Your fire risk assessment decides the category. As a guide, BS 5839-1 (Annex A) gives these as typical:
Workplaces where nobody sleeps (offices, shops, factories, warehouses, restaurants): Category M, often combined with P1 or P2 for insurers.
Premises where people sleep (hotels, hostels, student accommodation, HMOs): L1 or L2.
Care homes and hospitals: L1.
Pubs with letting rooms: L2.
Typical fire alarm category by type of building
This table is from Annex A of BS 5839-1, reproduced in the Fire Industry Association’s guidance. It describes what’s typically installed, not what your building must have: the decision rests with your fire risk assessment and the enforcing authority.
| Type of premises | Typical category | Notes |
|---|---|---|
| Offices, shops, factories, warehouses and restaurants | M, P2/M or P1/M | Category M normally satisfies fire safety law. Property protection is often added for insurers, company policy or business continuity. |
| Hotels, hostels, student accommodation, HMOs and similar sleeping accommodation | L1 or L2 | Bedroom areas are designed much like L3, with detection in most other areas too, so the system is at least L2 and effectively L1. |
| Residential care premises | L1 | – |
| Hospitals | L1 (with possible minor variations) | See HTM 05-03 Part B in England and Wales. |
| Healthcare without sleeping accommodation, such as walk-in centres | L2 or L3 | See HTM 05-03 Part B. |
| Large pubs with no sleeping accommodation | M or P2/M | P2 is sometimes required by insurers, especially with a kitchen with frying equipment or ovens. |
| Pubs with sleeping accommodation | L2 | – |
| Schools (other than small single-storey schools with fewer than 160 pupils) | M, M/P2, M/P2/L4 or M/P2/L5 | Category P is often installed against arson; L4 or L5 where parts are used in the evening or by the community. |
| Places of assembly for fewer than about 300 people | M | Such as small cinemas, theatres, leisure centres and galleries. |
| Larger places of assembly | L1 to L4 | L1 is often provided in large or complex buildings. |
| Covered shopping centres | L1 to L3 | Decided case by case, often as part of a fire engineering solution. |
| Buildings with phased evacuation | L3 | – |
| Buildings with inner rooms and no vision panel to the access room | M/L5 | Smoke detection in the access room. |
| Buildings where detection operates other fire protection, such as magnetic door holders | M/L5 | – |
| Where fire could spread from an unoccupied area and block escape routes | M/L4 or M/L5 | – |
| Any building where a property insurer requires detection | M/P1 or M/P2 | – |
How to work out which category you need
Does anyone sleep in the building?
If yes (hotels, hostels, HMOs, care homes, flats above shops), expect extensive automatic detection: usually L1 or L2.
Is it a workplace where people are awake and know the building?
A manual Category M system usually meets fire safety law. Your assessment may add detection for a particular reason, such as lone working after hours (often L4), inner rooms or door holders (L5).
Does your insurer or business need property protection?
Insurers sometimes ask for P1 (throughout) or P2 (high-risk or high-value areas such as kitchens, stores or server rooms) on top of the life safety category.
Get it confirmed in your fire risk assessment
The category, and for L2, L3, L5 and P2 the areas to be covered, should be written in your fire risk assessment or specification before a system is designed.
The categories at a glance
| Category | What it means | Protects |
|---|---|---|
| M | Manual call points only; no automatic detection. People raise the alarm themselves. | Life |
| L1 | Automatic detection throughout all areas of the building. | Life |
| L2 | Detection in defined parts of the building, including everything an L3 system covers, plus rooms where a fire is more likely to start or would put lives at greater risk. Since 2025 this includes rooms where people sleep. | Life |
| L3 | Detection designed to warn early enough for everyone to escape, except possibly people in the room where the fire starts: escape routes and the rooms that open onto them. | Life |
| L4 | Detection in the circulation areas of escape routes, such as corridors and stairways. | Life |
| L5 | Detection in specific areas to meet a particular fire safety objective not covered by L1 to L4. | Life |
| P1 | Automatic detection throughout the building to protect property. | Property |
| P2 | Automatic detection in defined parts of the building, such as high-risk or high-value areas. | Property |
Who chooses the category?
The fire risk assessment. The Fire Industry Association’s guidance is clear that choosing the category is the job of the fire safety specialist, such as your fire risk assessor, a fire engineer or the enforcing authority, not the alarm designer or installer. Insurers sometimes ask for property protection as well. A good designer will explain the options and design to the category you need, and BS 5839-1 asks the designer to confirm the proposed category with you before an order is placed.
Make sure your fire risk assessor is independent of whoever will supply and install the system. If the assessor, or a company they’re connected to, would also sell or fit the fire alarm, they stand to gain from recommending a higher category than your building needs. That’s a conflict of interest, so ask about it before you appoint them. It’s also why we don’t set the category ourselves: we design to the category your assessment calls for.
Combining categories
Categories can be combined. A shop might have an M/P2 system: call points throughout, with property protection detection in the stockroom. A hotel might have L1 for life safety with P2 in a server room.
Homes, flats and HMOs: BS 5839-6
Domestic premises, including many HMOs, use BS 5839-6 instead. It has grades (A, C, D1, D2, F1, F2) describing the type of equipment and categories (LD1, LD2, LD3, PD1, PD2) describing where detection goes. Fire alarms for HMOs, flats and landlords.
Did the categories change in 2025?
The definitions of M, L1 to L5, P1 and P2 are the same in BS 5839-1:2025, but some of the recommendations for what they cover changed. L2 now includes rooms where people sleep, so heat detectors aren’t used there; stairway lobbies need automatic detection; the L3 rule for ceiling voids now refers to solid construction rather than “fire-resisting construction”; and L4 recommends a detector at the top of flue-like structures. What changed in BS 5839-1:2025.
Not sure what your building needs? Site surveys and advice are free: we’ll look at your fire risk assessment and design to the category it sets.
Questions
What fire alarm category do I need?
Your fire risk assessment decides. As a guide, BS 5839-1 says workplaces where nobody sleeps (offices, shops, factories, warehouses) usually need Category M, often with P1 or P2 for insurers; premises where people sleep (hotels, hostels, student accommodation, HMOs) usually need L1 or L2; and care homes and hospitals usually need L1.
Who decides which fire alarm category I need?
Your fire risk assessor or another fire safety specialist, such as a fire engineer or the enforcing authority, not the fire alarm installer. Ideally the assessor isn’t connected to whoever will supply and install the system. We design to the category your assessment sets and can explain what each option means for your building. How we design fire alarms.
What fire alarm category does an office need?
Usually Category M (manual call points and sounders), because people are awake and know the building. It’s often combined with P1 or P2 detection for insurers, or with some automatic detection (L4 or L5) where, for example, people work alone after hours or there are inner rooms.
What fire alarm category does a care home need?
BS 5839-1 gives Category L1 as typical for residential care premises: automatic detection throughout the building.
What fire alarm category does a hotel, hostel or HMO need?
Usually L1 or L2. Bedroom areas are designed much like an L3 system, with detection in most other rooms as well, so in practice few areas are left unprotected and the system is effectively L1. Smaller HMOs may instead fall under BS 5839-6, the standard for homes.
What fire alarm category does a school need?
Typically M, often with P2 detection against arson, or M with L4 or L5 detection where parts of the school are used in the evening. Small single-storey schools may need less. The fire risk assessment sets it.
Is L1 better than L2?
L1 covers every area of the building; L2 covers the escape routes, the rooms opening onto them and other higher-risk areas. More detection isn’t automatically better: it costs more and can mean more false alarms. The right category is the one your fire risk assessment calls for.
What’s the difference between L2 and L3?
L3 protects escape routes and the rooms that open onto them, so everyone except possibly the people in the room where the fire starts can escape. L2 includes all of that, plus other rooms where a fire is more likely to start or would put lives at greater risk. Since BS 5839-1:2025, L2 includes rooms where people sleep.
Can a fire alarm system have more than one category?
Yes. Categories are often combined, for example M/P2 (manual call points with property protection in high-risk areas) or L2 with P2 in a server room.
Did BS 5839-1:2025 change the fire alarm categories?
The definitions are the same, but some recommendations changed: L2 now includes rooms where people sleep (so heat detectors aren’t used there), stairway lobbies need automatic detection, the L3 ceiling void rule now refers to solid construction, and L4 recommends a detector at the top of flue-like structures.
Sources
- Fire Industry Association: guidance on selection and specification of fire alarm category (Version 2, January 2026), including BS 5839-1 Annex A
- Fire Industry Association: guide to the changes in BS 5839-1:2025
- BSI Knowledge: BS 5839-1:2025
This information is general guidance, not advice for any particular building, and standards and guidance change. Get advice from a competent person for your premises. See our website terms and disclaimer.