Fire Alarm Installation in Hertfordshire: Retrofits, Listed Buildings and Blocks of Flats

Why retrofits are most of the work

Most Hertfordshire buildings that need an alarm already exist. Fitting into them is a different job from a new build.

Market towns such as St Albans, Hertford, Hitchin and Bishop's Stortford have historic centres. Shops, pubs, offices and flats sit over each other in buildings that were converted more than once. The cable route, the ceiling height and the walls are all decided by what is already there.

• Floors that cannot be lifted and ceilings that hide timber, lath or old wiring
• Cable routes that would cross a fire-resisting wall or floor and need sealing afterwards
• Mixed use, where a shop alarm has to be heard in the flat above and the flat entrance door has to hold
• No drawings, so the escape routes and compartment lines are worked out on site

We survey first, plan device positions on a marked-up plan, and tell you what is hidden before the first cable goes in. If your alarm is more than a decade old and the panel is no longer supported, see when to replace a fire alarm system.

Listed and historic buildings: wireless systems

A radio system sends signals between devices without running cable through the fabric.

In a listed building, drilling, chasing and ceiling work can damage the very features that give the building its status. Altering a listed building usually needs listed building consent from the council's conservation team, so ask them before any fixings go in. A wireless system keeps the work small, reversible and easier to agree.

Wireless is still a BS 5839-1 system. It must be designed for the category you need, with battery life, radio signal strength and the loss of a device all planned and tested at commissioning. It is not a cheap-looking domestic kit on the wall. Read our guides to alarms for listed buildings, wireless fire alarms and wired versus wireless.

Churches and community halls are common in the county's villages and old centres. Fire alarms for churches and heritage buildings covers the detector choices that suit tall roofs and timber.

Communal systems in blocks of flats

Commuter-belt blocks, converted offices and new builds each raise a different question.

In a purpose-built block with a stay-put strategy, the flats usually have their own detection and the common parts are protected by smoke control, fire doors and, where the design calls for it, a communal system. Whether the building needs a communal alarm comes from its fire strategy and the fire risk assessment. Our guide do flats need fire alarms in communal areas explains how that decision is made.

• Converted offices and older houses split into flats often have a mixed set of detectors added over the years, with no single panel. We can review and rationalise them.
• Blocks with an evacuation strategy need a system that sounds throughout the building. Where residents may need to be alerted without a full alarm, see BS 8629 evacuation alert systems.
• Panels and call points in shared lobbies need a named person, a log book and a service contract. Without those, faults go unnoticed.

The communal system sits alongside the doors. A fire alarm does not replace the flat entrance doors or the compartment walls, and a fire door inspection is a separate job. Buying guidance for managing agents is in fire alarms for blocks of flats.

Which category of system do you need?

BS 5839-1 uses L categories for life protection and P categories for property protection.

Your fire risk assessment decides the category, not the installer's preference. Escape-route-only cover is L3, wider cover is L2 and full coverage is L1. An office usually sits at L2 or L3, and a building with sleeping risk is normally designed higher. Our page on alarm categories sets this out, and what BS 5839 says covers the standard.

If you do not have an assessment, we recommend one first. See fire risk assessments in Hertfordshire. An alarm designed without one can be the wrong size for the building.

After installation: testing, servicing and monitoring

An alarm fitted once and forgotten is a liability.

1. 1Commissioning and certificates. The system is tested end to end. You get design, installation and commissioning paperwork.
2. 2Weekly test. A named person tests a call point each week and writes it in the log book. See how to do a weekly fire alarm test.
3. 3Six-monthly service. BS 5839-1 recommends servicing at intervals not exceeding six months. See how often alarms need servicing.
4. 4Monitoring if you want it. A signal to a monitoring centre means someone acts when the building is empty. See fire alarm monitoring.

Emergency lighting goes in the same visit where it is needed. Our emergency lighting guide covers BS 5266-1.

Sources

• Regulatory Reform (Fire Safety) Order 2005 (legislation.gov.uk)
• Fire safety in purpose-built blocks of flats (GOV.UK)
• Workplaces and businesses: business fire safety (Hertfordshire County Council)

Updated October 2026 by Sebastian Grabowski, DC Fire & Security, 2 Winsdon Court, Luton LU1 5LZ.