Fire alarm grades and categories for flats and HMOs

BS 5839-6 applies to domestic premises, meaning dwellings. BS 5839-1 applies to everything else. The confusion in blocks of flats and HMOs is that a single building is usually both at once: the corridors, stairs and plant rooms are non-domestic and fall under BS 5839-1 and the Fire Safety Order, while the inside of each flat is domestic and falls under BS 5839-6. One building, two standards, applied to different parts of it.

A grade tells you what the system is built from and, above all, how it is powered and controlled. It says nothing about how many rooms have detectors in them. Reading the grades in order of how much they depend on somebody remembering to do something makes them much easier to hold on to.

A category tells you which rooms get a detector and nothing about the equipment. The LD categories protect life. They are numbered so that the lower the number, the more of the building is watched, which is the opposite of what most people assume on first reading.

This is the point that makes the rest of it usable. The grade and the category are chosen independently, and any combination is possible. A building can be given a Grade A system covering escape routes only, which is Grade A LD3. Another can be given interlinked mains alarms covering escape routes and the kitchen, which is Grade D1 LD2. Reading "Grade A LD2" as a single quality level, rather than as a statement about the equipment followed by a statement about the coverage, is what leads to quotations that answer one half of the specification and quietly ignore the other.

This trips up more landlords than the standard does. The Fire Safety Order 2005 covers the common parts of a block of flats or an HMO: the corridors, the stairs, the bin store, the plant room. Conditions inside an individual dwelling are dealt with under housing legislation instead, through the Housing Health and Safety Rating System, and for licensable HMOs through the conditions attached to the licence. On top of both sits the Smoke and Carbon Monoxide Alarm regulations, which set a minimum for rented homes regardless of what anything else says.

LACORS housing fire safety guidance is not law. It is the practical guidance that local authority housing teams in England and Wales generally work from when they judge whether the fire precautions in a shared or rented property are reasonable, and it is written around exactly the grade and category vocabulary above. When a licensing officer tells you the property needs a particular standard of alarm system, this is usually the document behind the statement, which makes it worth knowing by name even though you will never be prosecuted under it.

Buying to the grade without buying to the category, or the reverse. An installer who prices a Grade A panel system and then covers escape routes only has delivered expensive equipment doing a modest job. An installer who covers every room with battery alarms has delivered coverage that nobody will maintain and that a licensing officer will not accept. Both quotations can honestly claim to have met half of what the assessment asked for, which is why the specification has to be read as two requirements and checked as two requirements.