BS 5839-6 is the British Standard for fire detection and alarm systems in domestic premises: houses, flats, HMOs and sheltered housing. It describes a system with two labels: a grade, which says how the system is built and powered, and a category, which says where the detectors go. A typical requirement reads "Grade D1, Category LD2".
Grades: how the system is built
- Grade A: a full system with a control panel, manual call points and detectors that meet the BS EN 54 standards, similar to a commercial system. Used in larger HMOs and sheltered housing.
- Grade C: detectors and sounders connected to a central control with a standby supply, without the full specification of Grade A.
- Grade D1: mains-powered alarms with a tamper-proof standby battery, interlinked. The most common choice for rented homes and small HMOs.
- Grade D2: mains-powered alarms with a user-replaceable standby battery.
- Grade F1: alarms powered by a tamper-proof, long-life battery.
- Grade F2: alarms powered by a user-replaceable battery.
Grades A to D need a mains supply. Grade F alarms are battery only and are generally the minimum for owner-occupied homes rather than rented ones.
Categories: where the detectors go
- LD1: detectors in all escape routes and all rooms where a fire might start, except bathrooms and toilets. The highest level of life protection.
- LD2: detectors in all escape routes and in rooms that pose a high risk to occupants, typically the living room and kitchen.
- LD3: detectors in escape routes only, such as hallways and landings.
- PD1 and PD2: property protection categories.
- Category M: manual call points only.
Kitchens usually get heat detectors rather than smoke detectors, to avoid false alarms from cooking.
Typical requirements
- Owner-occupied house: at least Grade D2 LD3 is recommended, and LD2 is better. In Scotland, the national interlinked alarm rule applies to every home.
- Rented house (single household): Grade D1 or D2, LD2 is common.
- Small HMO (up to two storeys): Grade D1 LD2 is typical.
- Larger HMO (three or more storeys): often Grade A LD2.
- Bedsit HMO: detection in every bedsit, interlinked.
Councils set their own HMO licence conditions, which take priority. Our HMO fire alarm finder gives a quick indication for your property.
Testing
Grade D and F alarms should be tested regularly using the test button, at least monthly. Grade A systems need periodic servicing by a competent engineer, normally every six months.
This guide is general information about UK fire safety law and standards, not legal advice for a specific building. If you are unsure what applies to yours, ask us or a qualified adviser.