Fire alarm installation means designing and fitting a system that suits the building and the law: interlinked mains-powered alarms to BS 5839-6 for homes and HMOs, or a panel system to BS 5839-1:2025 for businesses and larger buildings. BritCertify installs across London from £119 per smoke or heat detector and from £1,299 for a fire alarm panel, inc. VAT.
What type of fire alarm does my property need?
It depends on how the building is used, how many storeys it has, who sleeps there, and what your fire risk assessment, HMO licence or building control asks for. We design to that requirement rather than to a standard package.
| Property | Typical system | Standard |
|---|---|---|
| Single-let flat or house | Interlinked mains alarms with standby batteries: smoke alarms on the escape route, a heat alarm in the kitchen, CO alarms beside fixed combustion appliances | BS 5839-6 |
| Shared house or small HMO | Grade D interlinked alarms, with LD2 or LD3 coverage as the licence specifies | BS 5839-6 and LACORS guidance |
| Larger HMO or bedsit house | Grade A panel system with detectors, sounders and call points | BS 5839-6 |
| Communal areas of a block | Only where the evacuation strategy requires a communal alarm | Set by the fire risk assessment |
| Shop, office, restaurant or warehouse | Panel system to the category your fire risk assessment specifies | BS 5839-1:2025 |
If you do not have a current fire risk assessment, it is worth arranging one first so the system is specified correctly and you only pay for what the building needs.
What do the Grades and Categories mean?
The Grade describes the equipment and how it is powered and controlled. The Category describes how much of the building has detection.
| Term | Meaning |
|---|---|
| Grade A | Control panel with separate detectors, sounders and manual call points, using components to BS 5839-1 |
| Grade D1 | Mains-powered alarms with a tamper-proof standby battery |
| Grade D2 | Mains-powered alarms with a user-replaceable standby battery |
| Grade F1 / F2 | Battery-only alarms, with a sealed or a replaceable battery |
| LD3 | Detection on escape routes only |
| LD2 | Escape routes plus rooms where fire is more likely to start, such as kitchens and living rooms |
| LD1 | Escape routes and every room where a fire could start |
| L1–L5, M, P1–P2 | Non-domestic categories under BS 5839-1:2025 for life protection, manual alarm only and property protection |
Where do detectors go in a typical London home or HMO?
Detectors go where they will give the earliest useful warning without false alarms. The exact layout follows the Category your property needs, but in most London flats, houses and HMOs it looks like this.
| Location | Detector | Why |
|---|---|---|
| Hallway and every landing | Smoke | Protects the escape route on each storey |
| Living room | Smoke | A room where fires often start, covered in an LD2 layout |
| Kitchen | Heat | Detects a fire without reacting to cooking fumes or steam |
| HMO bedrooms | Smoke | Where the licence or the fire risk assessment calls for LD2 or LD1 coverage |
| Room with a boiler, gas fire or wood burner | CO alarm | Required under the 2022 alarm regulations |
| Loft conversion | Smoke | A new storey needs its own detection, linked to the rest |
Bathrooms and shower rooms are left without detection, and smoke alarms are kept away from kitchen doorways, because steam and cooking are the most common causes of false alarms in rented homes.
Wired or wireless interlinked alarms?
Both can meet BS 5839-6 when designed and installed properly. The choice usually comes down to access and disruption.
- Hard-wired interlink: a cable runs between the alarms. Very reliable, and well suited to refurbishments where ceilings are already open.
- Radio interlink: each alarm is still mains-powered, but the alarms talk to each other by radio. Far less cabling, which suits occupied flats and period properties with decorative ceilings and cornicing.
For panel systems, the choice is between conventional panels, which report by zone and suit smaller buildings, and addressable panels, which identify the exact device in alarm and suit larger or multi-occupied premises.
What happens during an installation?
A typical job runs through survey, design, installation, commissioning and handover. On London jobs the details matter:
- In Victorian conversions we plan cable routes to avoid lifting floorboards and damaging lath-and-plaster ceilings wherever possible.
- In occupied HMOs we work room by room, give tenants notice and keep the existing alarms working until the new system is commissioned.
- Every new hole through a fire-resisting wall or ceiling is fire-stopped, so the installation does not weaken the building’s separation.
- Grade A and commercial systems use fire-resisting cable as BS 5839-1 requires, and all mains wiring is installed to BS 7671.
At commissioning we test every device, check that all alarms sound together, and show you or your staff how to test, silence and reset the system. You receive the commissioning paperwork and logbook, which your licensing officer, insurer or fire risk assessor may ask to see.
When should an existing alarm system be replaced?
When it no longer matches the building’s risk, when parts reach the end of their life, or when your fire risk assessment or licence asks for more.
- Alarms past the replace-by date printed on them.
- Battery-only alarms in an HMO where the licence requires mains-powered interlinked alarms.
- Old panels for which spare parts are no longer available.
- A loft conversion, extension or change of use, such as a house becoming an HMO.
- Repeated false alarms caused by the wrong type of detector in the wrong place, such as a smoke detector beside a kitchen or shower room.
False alarms matter more than they seem. Every unwanted activation teaches occupants to ignore the alarm, and in HMOs it is often what leads tenants to cover or disconnect detectors.
Replacement does not always mean starting again. Where the existing wiring is sound and suitable, we can often keep it and upgrade the alarms, add detectors to reach the Category your licence now requires, or swap the wrong detector types. The survey tells you which parts can stay and which cannot, so you only pay for the work the building needs.
How much does fire alarm installation cost in London?
Smoke and heat detectors are supplied and installed from £119 each inc. VAT, and a fire alarm panel installation starts at £1,299. Cable routes, ceiling access and making good affect the final figure, so we confirm the price in writing after survey.
Once installed, a BS 5839-1:2025 system needs servicing every 6 months, and many HMO licences require an annual alarm certificate; our fire alarm certificate service covers both. If escape routes are dark, ask about emergency lighting installation at the same time, and request a quote with your property details. We hold £5 million public liability insurance.
Fire alarm installation prices in London (inc. VAT)
| Option | Price (inc. VAT) | Notes |
|---|---|---|
| Smoke or heat detector installed | from £119 | Per detector, supplied and fitted |
| Fire alarm panel installation | from £1,299 | Control panel for a Grade A or commercial system |
| Larger and addressable systems | Quote | Priced after a site survey |
All prices include VAT and are from prices; cable routes, ceiling access and making good affect the final cost. Central London parking or Congestion Charge may be added; we always confirm before booking.
Book this serviceWhat's included
- System design to BS 5839-6 or BS 5839-1:2025
- Supply and fitting of detectors, sounders and panel
- Interlinking of all alarms
- Fire stopping of any new holes through fire-resisting walls
- Full commissioning test of every device
- Handover paperwork and logbook
- Demonstration of testing, silencing and reset
How it works
Survey
We review the property's use, layout, licence conditions and any fire risk assessment recommendations, then design the right Grade and Category.
Written quote
You receive a written quote listing detectors, panel, cabling and making good, from £119 per detector and £1,299 per panel inc. VAT.
Installation
We fit the system with minimal disruption, fire-stop new holes through fire-resisting walls and keep existing alarms working until handover.
Commission and hand over
Every device is tested, you are shown how to test and reset the system, and you receive the commissioning paperwork and logbook.
Fire Alarm Installation: frequently asked questions
Do landlords have to install mains-powered smoke alarms?
Not under the 2022 alarm regulations, which do not specify the power source. However, HMO licence conditions, building work such as loft conversions and extensions, and BS 5839-6 recommendations often call for mains-powered interlinked alarms. For most rented homes they are the more reliable choice, because tenants cannot simply remove a battery after a false alarm.
How long does a fire alarm installation take?
It depends on the size of the property and how the alarms are linked. Radio-interlinked mains alarms in a flat are usually a short job with little disruption. Hard-wired systems in larger houses, and panel systems in HMOs or commercial premises, are planned over one or more visits. We give you the timetable with the quote, so tenants or staff can be told in advance.
What is the difference between a smoke alarm and a heat alarm?
A smoke alarm detects smoke particles and gives the earliest warning, so it belongs on escape routes and in living areas. A heat alarm responds to a high or rapidly rising temperature and ignores cooking fumes and steam, which makes it the right choice for kitchens. Heat alarms are not suitable for hallways, because they react later than smoke alarms.
Can you install a fire alarm in an occupied HMO?
Yes. We plan the work room by room, give tenants written notice of access times and keep the existing alarms working until the new system is tested and commissioned, so the house is never left unprotected. Where possible we choose cable routes and radio-interlinked equipment that limit dust and disruption in occupied rooms.
Do I need a fire alarm panel, or will interlinked alarms do?
For most single-let homes and smaller shared houses, interlinked Grade D alarms are sufficient. Larger HMOs, bedsit houses and commercial premises usually need a Grade A or BS 5839-1:2025 panel system, which shows where an alarm started and supports call points and more sounders. Your fire risk assessment and licence conditions decide, and we design to them.
What maintenance does a new fire alarm system need?
Panel systems under BS 5839-1:2025 need servicing every 6 months, within a 5–7 month window, plus a weekly user test from a different call point. Grade D alarms should be tested regularly using the test button, checked at the start of each tenancy and replaced by the date printed on them. Many London HMO licences also require an annual alarm certificate.
Sources and official guidance
Written and checked by the BritCertify technical team. Last reviewed 6 October 2026.