HMO Planning Rules — Article 4 Directions, C4 vs Sui Generis, and What You Need to Know

**The Town and Country Planning (Use Classes) Order 1987** (as amended) classifies land uses into categories. Changes within the same use class do not require planning permission; changes between use classes do.

**C3 — Dwellinghouse**: a single family home or a home occupied by no more than 6 people living as a single household (or caring relationship). This is where all standard residential properties start.

**C4 — Houses in Multiple Occupation**: a house occupied by 3–6 people who share facilities (kitchen, bathroom, living room) but are NOT a single household. A standard Victorian terrace converted to 3–6 letting rooms is a C4 HMO.

**Sui Generis HMOs**: HMOs occupied by 7 or more people (i.e., larger HMOs) do not fall within the C4 class — they are 'sui generis' (a class of their own). A change to a sui generis HMO always requires planning permission regardless of any Article 4 Direction.

• **What this means in practice**:
• •Changing from C3 (single family home) to C4 (3–6 person HMO) is a change of use that would normally be Permitted Development — no planning permission required
• •UNLESS the local authority has removed that PD right by applying an Article 4 Direction
• •Changing from C3 or C4 to a sui generis HMO (7+ people) ALWAYS requires planning permission, everywhere

**What is an Article 4 Direction?** An Article 4 Direction is a direction made by a local planning authority that removes Permitted Development rights in a specified area. When an Article 4 Direction removes the C3-to-C4 PD right, a planning application is required to convert any C3 dwelling to a C4 HMO in the affected area.

**Why do councils use Article 4 Directions for HMOs?** Many London boroughs have applied Article 4 Directions to all or part of their area to control the spread of HMOs. The concern is that high concentrations of HMOs in residential streets change the character of neighbourhoods, reduce family housing supply, and can cause amenity issues.

• **London boroughs with HMO Article 4 Directions** (position as of mid-2026 — always verify with the specific borough):
• •**Southwark**: Article 4 Direction covers most of the borough — planning permission required to convert C3 to C4 HMO
• •**Lewisham**: Article 4 Direction in parts of the borough
• •**Croydon**: Article 4 Direction covering most residential areas
• •**Brent**: Article 4 Direction in place
• •**Harrow**: Article 4 Direction in place
• •**Newham**: Article 4 Direction covering most of the borough
• •**Ealing**: Article 4 Direction in place

Many other London boroughs have Article 4 Directions in specific wards or neighbourhoods. Always verify the current position with the relevant local planning authority before purchasing an HMO investment property or commencing conversion works.

**How to check**: Contact the planning department of the relevant borough and ask specifically whether an Article 4 Direction removing the C3-to-C4 right applies at the specific address. A pre-application enquiry can confirm this. Many boroughs also publish their Article 4 Direction maps online.

**What happens if you convert without the required planning permission?** Converting a C3 property to a C4 HMO in an Article 4 Direction area without obtaining planning permission is a breach of planning control. Enforcement action can be taken, and you may be required to return the property to C3 use. Planning permission may be sought retrospectively — but refusal is a real risk in Article 4 areas where councils are actively managing HMO density.

Where planning permission is required for a C4 HMO conversion (in an Article 4 Direction area), the application will be assessed against the development plan policies for the borough. Key planning considerations typically assessed:

**HMO concentration**: most London boroughs with Article 4 Directions have policies that seek to limit the concentration of HMOs in any street or neighbourhood. Common policies set a maximum proportion of HMOs in a defined area (e.g., no more than 10% or 20% of properties in a defined street). If the threshold is already met, a planning application may be refused regardless of other merits.

**Amenity**: the LPA will consider the impact on residential amenity — noise, waste management, parking, and the overall character of the neighbourhood.

**Parking**: in areas with parking pressure, additional car ownership from additional residents may be a material consideration.

**Standards for the HMO itself**: while planning is about land use rather than internal standards, the planning officer may consider the size and quality of the accommodation proposed. Very small rooms or inadequate shared facilities may raise concerns.

**Proximity to other HMOs**: some boroughs maintain registers of HMOs and map concentrations. Proximity to existing HMOs in a concentrated area may be a ground for refusal.

HMO planning and HMO licensing are two entirely separate systems:

**Mandatory HMO licensing** (national requirement): In England, all HMOs occupied by 5 or more people forming 2 or more households, in a property of 3 or more storeys, are subject to mandatory HMO licensing by the local authority. A licence is required before the HMO can be occupied.

**Additional licensing schemes** (borough discretion): Many London boroughs have introduced Additional Licensing schemes that extend mandatory licensing to smaller HMOs — typically all HMOs with 3+ occupants in 2+ households, regardless of storey count. These must be checked borough by borough.

• **Key HMO licence conditions**:
• •Minimum room sizes (since 2018: 6.51m² for a single adult, 10.22m² for two adults)
• •Adequate shared facilities (kitchen, bathroom) for the number of occupants
• •Fire safety requirements (fire alarm system, fire doors, escape routes)
• •Electrical Installation Condition Report (EICR)
• •Gas Safety Certificate (annual)
• •EPC rating
• •Maximum number of occupants specified in the licence

**The HMO planning and licensing interaction**: A successful planning application for C4 use does not guarantee that a licence will be granted — the licensing authority will assess the property against HMO standards independently. Conversely, a licence does not regularise a breach of planning control. Both planning permission AND a licence are required.