There is no national HMO fire alarm specification. The requirement reaches a landlord through the licence conditions the council attaches to that property, informed by a fire risk assessment and by national guidance on fire safety in shared housing. That is why two identical houses in neighbouring boroughs can be told to fit different systems and both answers are correct.
Where the requirement comes from
Licensable HMOs carry licence conditions issued by the local housing authority, and those conditions normally state the grade and category of alarm system required. Alongside that, the common parts of an HMO fall under fire safety law, so the fire risk assessment applies too. The two are meant to agree, and where they do not, the licence condition is the one with a direct enforcement route.
Grade and category together
An HMO specification normally names both: a grade describing the equipment, typically mains powered with standby supply and interlinking, and an LD category describing coverage. Meeting one without the other is the classic failure. A house with alarms in every required room, all battery powered where a mains grade was specified, fails on grade while looking compliant to anybody counting devices.
Why the answer varies
Councils apply national guidance on fire safety in shared housing to local stock, and the assessed risk genuinely differs: number of storeys, number of households, whether there is a shared kitchen, whether occupants are students or families, whether the escape route is protected. A bedsit style HMO with shared cooking is a different risk from a shared house with a single kitchen, and the specifications reflect that.
What to do first
Get the licence conditions for that specific property in writing before buying anything, and get the fire risk assessment done by somebody who has read them. Fitting a system and then asking the council is the expensive order to do it in, because a system of the wrong grade cannot be upgraded by adding devices.
Questions people ask about hmo fire alarm requirements
What fire alarm does an HMO need?
Whatever the licence conditions for that property specify, normally a stated grade and an LD category, informed by the fire risk assessment. There is no single national answer.
Why does my council require more than the one next door?
Because the requirement follows the assessed risk of the specific property and the way that authority applies national guidance on shared housing. Different stock genuinely warrants different systems.
Do I need a fire risk assessment as well as the alarm?
Yes. The common parts of an HMO are covered by fire safety law, so the assessment is a separate duty from anything the licence says about equipment.