Overcrowding is more common than many landlords realise — particularly in the HMO sector and in areas with high housing demand. The most frequent cause is unauthorised subletting: a named tenant sublets a room to an additional occupant without the landlord's knowledge, pushing occupancy above the permitted level. Including an anti-subletting clause and carrying out regular inspections are the most practical preventive measures.
For HMO operators, the minimum room sizes introduced under the 2018 HMO licensing regulations are an absolute floor — a room that does not meet the minimum size cannot be used as a bedroom for an adult regardless of the licence conditions or tenant demand. Councils inspect HMO room sizes during licence inspections.
The Housing Act 1985 overcrowding standards
Two separate standards determine whether a property is overcrowded in law:
- Room standard: a property is overcrowded if persons of opposite sexes aged 10 or over who are not a couple must sleep in the same room. This standard applies regardless of room size — a large bedroom shared by an adult brother and sister triggers the room standard
- Space standard: a property is overcrowded if the number of occupants exceeds the permitted number for the available rooms. Rooms below 50 sq ft cannot count; rooms of 50–70 sq ft count as half a person; rooms of 70–90 sq ft count as one person; rooms above 90 sq ft count as two persons
- Criminal offence: a landlord who knowingly permits overcrowding is guilty of an offence under section 331 of the Housing Act 1985. Maximum fine in a magistrates' court is unlimited
- Civil penalty: local authorities can impose civil penalties of up to £30,000 for overcrowding offences as an alternative to prosecution — a faster and more commonly used route
- Local authority power: the council can serve an Overcrowding Notice specifying the maximum number of permitted occupants and prohibiting additional persons from being permitted to sleep in the dwelling
HMO minimum room sizes — the 2018 regulations
HMO room sizes are regulated under the HMO licensing regulations:
- Single bedroom (one adult): minimum 6.51 square metres of usable floor area. A room below this size cannot lawfully be used as a single bedroom under the HMO licensing conditions
- Shared bedroom (two adults): minimum 10.22 square metres. A room used by two adult occupants must meet this minimum
- Children under 10: minimum 4.64 square metres for rooms used by a child under 10
- Usable floor area: areas under 1.5m ceiling height are typically excluded from the usable floor calculation — relevant for attic rooms and rooms with sloped ceilings
- HMO licence conditions: licences specify the maximum number of occupants per room and per property. Exceeding licence conditions — including using a sub-standard room as a bedroom — can result in licence revocation and civil penalties
HHSRS overcrowding assessment
Overcrowding is a recognised hazard under the Housing Health and Safety Rating System:
- Overcrowding appears as Hazard 29 in the HHSRS — assessed for the risk it poses to occupants (psychological harm, spread of infection, increased accident risk in crowded living conditions)
- Local authority inspection: the council can carry out an HHSRS inspection on receipt of a complaint about overcrowding. If overcrowding is identified as a Category 1 hazard, the council must take enforcement action
- Enforcement options: Improvement Notice (requiring reduction in occupancy), Prohibition Order (restricting use of part of the property), or Emergency Prohibition Order (immediate effect) in severe cases
- Prosecution: a landlord who knowingly permits overcrowding can be prosecuted. Courts can impose unlimited fines in a magistrates' court for continued overcrowding following a Prohibition Order
- Civil penalties: local authorities can impose civil penalties up to £30,000 per offence — used increasingly in preference to prosecution for a faster resolution
Tenant subletting — the most common cause of overcrowding
Most overcrowding cases arise through unauthorised subletting — address this proactively:
- Include an anti-subletting clause in every tenancy agreement: 'The tenant shall not sublet or share occupation of the property or any part of it without the landlord's prior written consent'
- A tenant who sublets without consent breaches the tenancy on Ground 12 (breach of any obligation of the tenancy). This is a discretionary possession ground — you must show the breach and that it is reasonable to grant possession
- Carry out regular mid-tenancy inspections (at least annually, with proper notice). Note the number of persons present and investigate if you observe signs of additional occupancy (extra bed, additional belongings beyond the named tenants)
- Reference all adult occupants at the start of the tenancy — not just the named tenant. This provides a baseline record of intended occupants
- If subletting is discovered: serve a written notice on the subletter requiring them to vacate. If the principal tenant does not remedy the breach, consider serving a Section 8 notice on Ground 12
Preventing overcrowding — practical steps for landlords
A proactive approach reduces the risk of enforcement action and tenant disputes:
- Specify the maximum permitted occupants in the tenancy agreement and in the HMO licence (where applicable). This creates a clear contractual baseline
- Regular inspections: mid-tenancy inspections (at least annually) allow early identification of additional occupants. Document inspection findings with photographs and a written report
- Tenancy agreement occupancy clause: 'The property may only be occupied as a private residence by the persons named in this agreement and not more than [X] persons in total'
- HMO licence compliance: confirm that each room used as a bedroom meets the minimum size requirements before licensing. Do not allow additional occupants to exceed the licence conditions — the council may inspect at any time
- Prompt response to complaints: if a neighbour or the local authority raises concerns about overcrowding, investigate and respond promptly. A documented proactive response reduces the risk of enforcement action and demonstrates good faith
Frequently asked questions
What is the maximum number of people who can legally live in a property?+
There is no single universal answer — the maximum depends on the space standard under the Housing Act 1985 (number of rooms and their sizes), HMO minimum room sizes if the property is licensed as an HMO, and the HMO licence conditions (which specify the maximum occupancy). The practical maximum is determined by the smallest of these constraints. A calculation based on room sizes and the Housing Act 1985 space standard is the starting point — consult a housing professional or the local authority's housing team if you are uncertain.
Can I be prosecuted for overcrowding if I did not know about it?+
The Housing Act 1985 overcrowding offence requires that the landlord 'knowingly permits' overcrowding — so genuine ignorance is a defence. However, a landlord who fails to carry out inspections or who ignores obvious signs of additional occupancy (e.g. significantly increased utility usage, multiple names appearing on correspondence) may be found to have known or ought to have known. Regular inspections and a well-documented inspection record are the most effective defence against a 'knowingly permitted' prosecution.
My tenant has moved in additional people without telling me — what should I do?+
Serve a written notice on the tenant requiring them to reduce occupancy to the permitted level by a specified date (typically 14–28 days). If the breach is not remedied by that date, serve a Section 8 notice on Ground 12 (breach of tenancy obligation) — the anti-subletting clause in your tenancy agreement is the relevant obligation. Ground 12 is discretionary, so you must also establish that it is reasonable to grant possession. Document all steps carefully.
Does overcrowding affect my HMO licence?+
Yes — if a council inspection reveals that occupancy exceeds the licence conditions, or that rooms below the minimum size are being used as bedrooms, the council can impose additional licence conditions, suspend the licence, or commence revocation proceedings. A licence revocation requires a new application and can leave you operating an unlicensed HMO during the process — with associated penalties. Address any overcrowding immediately on discovery and notify the council proactively.