Do I need a fire alarm system?
The law requires a way of warning everyone in the building. For a small, simple premises that can be a shout or a hand bell; for most others it is a system to BS 5839-1. What category you actually need, how servicing really works, what the weekly test is, and why a service contract is where small businesses get locked in.
Looking for the technical detail? Read the version for professionals → BS 5839-1:2025 categories, design, commissioning, servicing schedules and false-alarm management.
Do I need one? You need a way of warning everyone in the building that there's a fire. What that means for your premises comes out of your fire risk assessment. For a small single-room shop it can be a shout. For most businesses it means an installed system.
Who decides what system? Your fire risk assessment. Not the alarm company. That order matters, because the alarm company has an obvious interest in the answer.
Where does it go wrong for buyers? Not usually on the install. On the service contract: twice-yearly visits sold on three- and five-year terms with auto-renewal, and a weekly test you're paying someone to do that takes you five minutes.
What the law actually requires
The Regulatory Reform (Fire Safety) Order 2005, article 13: where necessary to safeguard the safety of relevant persons, the responsible person must ensure the premises are, to the extent appropriate, equipped with appropriate fire detectors and alarms. Article 17: any fire safety equipment must be maintained in an efficient state, in efficient working order and in good repair.
"To the extent appropriate" is the whole game. The fire risk assessment decides what's appropriate. The Order doesn't specify a category, a standard or a servicing interval. Scotland and Northern Ireland impose the same duty under their own legislation.
The code of practice for fire detection and alarm systems in non-domestic premises. Not law, but it's what fire officers, insurers and courts treat as the benchmark for "appropriate" and "maintained". It sets the system categories, the design rules, and the servicing regime: weekly user test, six-monthly inspection and service, all devices tested annually. The 2025 edition replaced BS 5839-1:2017. An existing system doesn't have to be upgraded because the edition changed.
Insurers frequently require a system to BS 5839-1 of a particular category, serviced by a third-party-certified company (BAFE SP203-1 is the usual scheme), and will ask for the service records after a fire. Check the policy wording: "serviced by a competent person twice a year" is common; "on a maintenance contract" is rarer than the sales pitch suggests.
What this means for your premises
The category is the decision that drives everything else, and it's your assessor's decision.
Small, simple, single-occupier, no sleeping (a small shop, a café, a ground-floor office): often Category M (manual call points, no automatic detection) or a very simple L4. Some are small enough that the assessment concludes a shouted warning is adequate. Domestic smoke alarms sometimes get accepted here; they are not a BS 5839-1 system and an insurer may say so.
Ordinary commercial premises with more rooms and people: L4 (detection on escape routes) or L3 (escape routes plus the rooms opening onto them). This is most offices, shops and restaurants.
Sleeping risk (hotels, B&Bs, HMOs, care homes, flats above): L2 or L1, with detection in bedrooms and high-risk rooms. No shortcuts here.
Property protection (P categories): only where you or your insurer want the building protected when it's empty, and usually in addition to a life-safety category.
Your options
Installation
Get the category from the fire risk assessment first. Then get two or three quotes to that specification from BAFE SP203-1 registered companies, and make sure each quote says which category it's designing to. A quote that doesn't name the category isn't a quote for your building.
Conventional systems (zoned, cheaper, fine for small premises) versus addressable systems (each device identified at the panel, better for larger or complex buildings). For a small premises, conventional is usually the right answer, whatever the salesperson prefers.
Servicing: the two layers
Layer 1: the weekly test, by you. Operate a different manual call point each week, confirm the sounders and the panel respond, reset, and write it in the log book. Five minutes. Free. Required by the standard, and it's the single most common gap fire officers find. Do not pay anyone to do this.
Layer 2: six-monthly inspection and service, by a competent engineer. Two visits a year, with the engineer testing all devices across the year, checking the panel, batteries and cause-and-effect, and recording it in the log book. Use a BAFE SP203-1 company or an equivalent third-party-certified one. Pay per visit, or on a one-year agreement with a 30-day notice clause. That's the whole requirement.
Monitoring
Connection to an alarm receiving centre is an option, not a requirement, for most premises. Sleeping-risk premises and some insurers want it. Everyone else should decide on the merits, not because it came in the package.
What it should cost
A small conventional system installed: £500 to £2,000. A medium addressable commercial system: £2,000 to £8,000. Large or complex sites: £10,000 upwards. Six-monthly servicing: typically £100 to £400 a year for a small system, priced by the number of devices. Extra visits for false alarms or faults are usually charged per call-out; get the rate in writing.
What you shouldn’t be sold
- A higher category than your assessment requires. L1 everywhere is not "safer" for a small shop, it's more detectors to buy and service. The assessment sets the category.
- The weekly test as a paid service. It's yours to do, it takes five minutes, and it's in the log book either way.
- A three- or five-year service contract with auto-renewal. The requirement is two visits a year by a competent person. Nothing about that needs a term. Read the notice clause before you sign anything.
- A new panel because of BS 5839-1:2025. The new edition doesn't make an existing system non-compliant.
- An addressable system for a two-room premises. Conventional is cheaper to buy and to service, and adequate for small buildings.
- Monitoring "included" in the package. It's a separate service with a separate monthly cost. Decide whether you need it.
- Assessment and installation from the same company on the same day. The assessment sets the category; the installer builds to it. When one company does both, the category tends to grow.
Check what else your business needs
The alarm is one part of your fire precautions. The same assessment covers emergency lighting and extinguishers. Run the Compliance Check to see everything your premises needs.
Sources
- Regulatory Reform (Fire Safety) Order 2005, articles 13 and 17 — legislation.gov.uk
- BS 5839-1:2025, Fire detection and fire alarm systems for buildings. Design, installation, commissioning and maintenance of systems in non-domestic premises
- FIA, Guide to the changes in BS 5839-1:2025 — fia.uk.com
- GOV.UK, fire safety risk assessment guides by premises type — gov.uk
- BAFE SP203-1 scheme — third-party certification for fire detection and alarm companies
Quick answers
- Is a fire alarm a legal requirement for a business?
- The law requires appropriate means of detecting fire and warning people, decided by your fire risk assessment. For a small single-room shop with a clear exit, a shouted warning or a manual bell can be enough. For anything larger, with more people, more rooms or sleeping risk, it means an installed system to BS 5839-1.
- What are the fire alarm categories, and which do I need?
- Category M is manual call points only. L1 to L5 are life-protection systems with automatic detection, L1 being everywhere and L5 being targeted at a specific risk. P1 and P2 protect property. Most small commercial premises need M, L4 (escape routes) or L3 (escape routes plus rooms opening onto them). Sleeping risk usually needs L2 or L1. Your fire risk assessment sets the category; the alarm company installs to it.
- How often does a fire alarm need servicing?
- BS 5839-1 recommends inspection and servicing at intervals not exceeding six months, so twice a year, with every device tested over the course of a year. Plus a weekly test of one call point by you, recorded in the log book.
- Can I do the weekly fire alarm test myself?
- Yes, and you should. Operate a different manual call point each week, check the alarm sounds and the panel responds, reset, and record it in the log book. It takes five minutes and needs no contractor.
- How much does a fire alarm system cost?
- A small conventional system, £500 to £2,000 installed. A medium commercial addressable system, £2,000 to £8,000. Large or complex sites, £10,000 upwards. Six-monthly servicing typically £100 to £400 a year for a small system.
- Do I need a fire alarm service contract?
- You need the system serviced twice a year by a competent person. You do not need a multi-year contract to achieve that. Pay per visit or take a one-year agreement with a 30-day notice clause. Anything longer is a lock-in you have no reason to accept.
- Are smoke alarms enough for a business?
- Domestic-grade smoke alarms are for homes and are not a BS 5839-1 system. They can be adequate for very small, simple premises where the fire risk assessment says so, but they are not what an insurer or a fire officer means by a fire alarm system.
- What is BS 5839-1:2025?
- The current British Standard for fire detection and alarm systems in non-domestic premises, published in 2025 and replacing the 2017 edition. It is a code of practice, not law, but it is what the Fire Safety Order treats as the benchmark. An existing system installed to the 2017 edition does not have to be replaced.
This is general information about UK compliance, written for the person paying the bill. It isn’t legal advice. If your situation is unusual, get a professional to look at it.