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Smoke Alarms and the Fire safety regulations

Smoke Alarms and the Fire safety regulations

Smoke Alarms and the Fire safety regulations.

There are different types of smoke alarms available to buy, but which is the right smoke alarm to use and what is the difference between them?

Key points about Fire Safety

Fire Safety is a key section of the building regulations and these regulations can vary throughout the UK, below you can find the government documents on the different building regulations for England & Wales, Scotland and Northern Ireland.

Regardless of where you live building regulations recommends:

  • A fire detection system should be provided in accordance with the relevant recommendations of BS5839 Part 6.
  • All alarms should be interlinked to ensure audibility throughout the property
  • Smoke alarms installed in circulation areas should use an optical type sensor, or a multi-sensor type which includes an optical sensor.

The different types of smoke alarms.

There are four mains types of fire detection alarms each with a different way of detecting the presence of a fire or smoke.

Ionisation: These alarms are generally the cheapest available. They use a sensor which detects the small particles of smoke produced by a fast flaming fire, such as paper and wood. When smoke is detected the alarm is triggered before smoke gets too thick.

Ionisation alarms are less sensitive to a slow burning or smouldering fire as they give off larger quantities of smoke before flaming occurs and can be too sensitive for use near kitchens and may be triggered by a toaster and other cooking appliances.


Optical: These alarms are more effective at detecting larger particles of smoke which are produced by a slow burning fire, such as over heating wires or foam commonly used in furniture.

As they are less sensitive to smaller particles an optical alarm is ideal for installing near (not in) a kitchen.


Heat Alarms: These alarms only detect an increase in temperature and are insensitive to smoke, this makes them ideal for use in kitchens.

Multi-sensor: These are a combination of optical and heat sensors, they generally provide an increased speed in detection whilst having a lower level of false alarms.


Check out our entire range of Smoke Alarms

How to position smoke alarms to meet Building Regulations

To meet the building regulations the property should meet the following:

England and Wales

The minimum guide for smoke alarm positioning in England and Wales for all dwellings should be an alarm system which meets Grade D and Category LD3. This means that the property is recommended to have:

  1. Mains powered smoke alarm with an optical sensor type within the escape route (i.e. hallways and landings)
  2. At least one smoke alarm fitted on each storey.
  3. Heat alarm in kitchen areas where the kitchen is not separated from the circulation space or stairway by a door.
  4. All alarms should be interlinked.

Scotland and Northern Ireland

In Scotland and Northern Ireland the minimum guide for smoke alarms is Category LD2 and a Grade D. This means that to meet the building standards the property is recommended to be fitted with:

  1. A smoke alarm in all circulation areas, escape routes and high risk areas.
  2. A minimum of one smoke alarm in every circulation space on each storey (i.e. hallways and landings)
  3. At least one smoke alarm in the principal habitable room (generally the living room)
  4. At least one heat alarm installed in every kitchen
  5. All alarms should be interlinked

In addition to this Scotland requires at least one smoke alarm to be installed in every access room serving an inner room.

Different categories in the Building regulations

Grades of systems

  • Grade A: A fire detection and fire alarm systems which incorporates control and indicating equipment installed to BS 5839: Part 1.
  • Grade B: A fire detection and fire alarm system comprising of fire detectors other than smoke alarms and heat alarms, fire alarm sounders and control and indicating equipment.
  • Grade C: A system of fire detection and alarm sounders (which may be combined in the form of smoke alarms) connected to a common mains power supply with back up and indicating.
  • Grade D: Mains powered alarms with an integral stand-by power supply (battery back-up).
  • Grade E: Mains powered alarms with no stand-by power supply.
  • Grade F: Battery powered alarms.

Categories of systems

  • LD1 Maximum Protection: Alarms in all circulation spaces that form part of escape routes and all areas where a fire might start, but not bathrooms, shower rooms or toilets.
  • LD2 Additional Protection: In all circulation spaces that form part of escape routes and rooms or areas that present a high fire risk.
  • LD3 Minimum Protection: Alarms in all circulation spaces that form part of escape routes.
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