The minimum floor area thresholds — 6.51m² / 10.22m² / 4.64m²
- 6.51m² — minimum for one person aged 10 or over (the most commonly applied threshold for single rooms in professional and student HMOs)
- 10.22m² — minimum for two persons aged 10 or over (shared rooms in budget HMOs and some student houses)
- 4.64m² — minimum for a person under 10; below this threshold a room cannot be used as sleeping accommodation by any person
- These thresholds apply to sleeping rooms only — not communal living areas, kitchens, bathrooms, or other non-sleeping spaces
- Where a living room is regularly used for sleeping, it falls within the scope of the regulations
How to measure HMO floor area correctly
- Measure internal dimensions (wall to wall, within plaster face) in metric; calculate length × width for rectangular rooms
- For loft conversions: exclude floor area under sections where headroom is below 1.5m — many loft rooms have measured areas below 6.51m² when low-headroom sections are excluded
- For irregular shapes: divide into rectangles and sum the areas
- Strongly recommended: measure all sleeping rooms before applying for a licence and before any enforcement inspection
Licence must specify each room and permitted occupant number
A mandatory HMO licence must specify each sleeping room and the maximum number of persons permitted per room. Using a room for more persons than the licence specifies is a licence breach — civil penalty up to £30,000.
Enforcement — improvement notices, penalties, and RROs
- Improvement notices (Housing Act 2004 s.11/12): served where rooms are below threshold and condition is ongoing; failure to comply is a criminal offence; authority can carry out works in default
- Licence revocation: operating in breach of licence conditions (including room sizes) is a ground for licence revocation under Housing Act 2004 s.70
- Civil penalties: up to £30,000 per offence; chosen by authorities over criminal prosecution in most cases; can be appealed to the First-tier Tribunal
- Rent Repayment Orders: tenants in unlicensed HMOs can apply for up to 12 months' rent — increasingly used by tenant advocates
Amenities — bathrooms, toilets, and kitchen ratios
- 1 bathroom/shower room per 4-5 occupants; 1 toilet per 4-5 occupants (separate where possible) — statutory guidance ratios, local authority conditions vary
- Kitchen: 1 cooker ring per 3-4 occupants; adequate refrigerator space and worktop/storage; large HMOs (7+) may require two kitchen spaces
- Fire safety conditions: interconnected smoke alarm system, heat detectors in kitchens, fire doors on sleeping rooms, emergency lighting — separate from room size requirements but equally mandatory