Do I Need Planning Permission for an HMO in London? (2026)
When a London HMO needs planning permission — small C4 vs large sui generis HMOs, Article 4 directions, licensing, and why the planning and licensing systems are separate.
The rules on houses in multiple occupation trip up more London landlords than any other part of the planning system, because two separate regimes — planning and licensing — apply at the same time and are often confused. Planning decides whether you can use a building as an HMO at all; licensing decides whether that HMO is safe and well-managed to occupy. A property can need one, both or neither depending on its size, its location and the borough. This guide explains when a London HMO needs planning permission in 2026, how Article 4 changes the answer borough by borough, and where licensing fits in.
The use classes are national, but Article 4 directions and licensing schemes are set locally across London's 33 boroughs. We confirm the use class, whether an Article 4 direction applies to your address, and the drawings a change-of-use application needs, before anything is commissioned, free.
Small HMO vs large HMO: the dividing line
Planning splits HMOs by occupancy. A small HMO — a shared house for three to six unrelated people who form more than one household and share facilities such as a kitchen or bathroom — falls in Use Class C4. A large HMO of seven or more sharers falls outside the use classes altogether as a sui generis use. The number of unrelated sharers, not the number of bedrooms, is what sets the class, and the class is what decides whether permission is needed. The concept of a household matters here and is frequently misread: people related by blood, marriage or civil partnership, and a domestic couple, count as a single household, so a five-bedroom house let to one large family is not an HMO at all, while the same house let room by room to five unrelated professionals is. It is the mix of separate households sharing amenities — not the size of the building or the rent — that brings a property into the HMO definition, which is why a modest terraced house can be an HMO while a large single-family home is not.
- 3–6 unrelated sharers sharing facilities — Use Class C4 (small HMO)
- 7 or more unrelated sharers — sui generis (large HMO)
- Households, not just people — a couple counts as one household
- It is occupancy that sets the class, not the number of rooms
When is a small HMO permitted development?
Changing a family dwellinghouse (Use Class C3) into a small HMO (Use Class C4) is permitted development nationally, which in theory means no planning application is needed. The catch is that this is one of the most widely restricted permitted-development rights in London. Boroughs concerned about the concentration of shared housing have made Article 4 directions removing the C3-to-C4 right, sometimes across the whole borough and sometimes ward by ward. Where an Article 4 direction is in force, converting even to a small HMO needs a full planning application. Article 4 directions are not uniform: some cover an entire borough, others only named wards or a single conservation area, and a handful are drawn to catch only larger conversions, so the direction has to be read for the specific address rather than assumed from the borough name. Many London boroughs also apply a policy threshold once an application is required — commonly refusing a new HMO where a set percentage of properties within a short radius are already HMOs, to prevent whole streets tipping into shared housing. That concentration test is often the real hurdle, not the principle of the conversion, and it is why two apparently identical houses on the same road can get opposite decisions depending on what their neighbours are already used for.
Why large HMOs always need planning permission
A large HMO of seven or more sharers is a sui generis use, meaning it sits in no use class and no permitted-development right can move a property into it. Creating one is therefore always a material change of use that needs a full planning application, in every London borough, regardless of Article 4. The council will assess amenity, the concentration of HMOs in the area, parking, refuse storage and the standard of accommodation. Large HMOs are where the planning bar is highest.
- Sui generis — outside the use classes, no PD route in
- Full planning application required in every borough
- Assessed on amenity, HMO concentration, parking, refuse, room standards
- Article 4 is irrelevant — permission is needed regardless
Planning vs licensing: two separate systems
Planning permission and HMO licensing are decided under different laws and answer different questions, and satisfying one does not satisfy the other. Under the Housing Act 2004, mandatory licensing applies to HMOs occupied by five or more people forming two or more households, and many boroughs run additional or selective licensing schemes that catch smaller HMOs too. A licence sets standards for room sizes, amenities, fire safety and management. You can have planning permission and still need a licence — and running an unlicensed HMO is an offence even where planning is not in question. The consequences of getting licensing wrong are serious and financial: operating a licensable HMO without a licence can lead to an unlimited fine or a civil penalty of up to thirty thousand pounds per offence, and it exposes the landlord to a rent repayment order under which tenants or the council can reclaim up to twelve months of rent. Selective and additional licensing schemes are declared by each borough for fixed periods and renewed, so a property that fell outside a scheme last year can be caught this year, which is why the licensing position should be confirmed at the point of purchase or conversion rather than assumed to be settled.
- Mandatory licence — 5+ occupants in 2+ households
- Additional/selective licensing — many boroughs extend this to smaller HMOs
- Licensing covers room sizes, amenities, fire safety, management
- A licence is required even where no planning permission is needed
How do I confirm the route for my HMO?
Three questions settle the planning side: how many unrelated sharers (small C4 or large sui generis), is the property in an Article 4 area, and is it currently a house (C3) or something else. If it is a small HMO outside an Article 4 area, permitted development may cover the change — but licensing will usually still apply. If it is a large HMO, or a small one inside an Article 4 area, plan for a full change-of-use application. We check the Article 4 position for your address, prepare the floor plans a change-of-use application and a licence both require, and lay out the room standards clearly.
What standards does an HMO actually have to meet?
Winning the planning argument is only the start; an HMO also has to be built and managed to standards that the licence enforces, and the drawings are where those two worlds meet. Two areas decide most schemes: whether the rooms are large enough to be lettable at all, and whether the fire-safety layout is compliant. Designing to both from the outset avoids the common trap of a planning consent for rooms that the licensing team will not accept.
Minimum room sizes and amenity standards
National mandatory licensing sets floor-area minimums for sleeping rooms in a licensed HMO — broadly 6.51 square metres for one person over ten years old, 10.22 square metres for two, and 4.64 square metres for a child under ten — and any room below 4.64 square metres cannot be used for sleeping at all. Many London boroughs layer higher standards on top through their own licensing conditions, along with ratios for shared kitchens, bathrooms and WCs based on the number of occupants. Rooms that look fine on a marketing plan often fall short once these thresholds are applied, so we size bedrooms and shared facilities against the licensing standard, not just the planning drawing.
Fire safety and means of escape
HMOs carry heavier fire-safety duties than single-family homes because unrelated occupants sleep behind separate doors. A compliant scheme typically needs a protected escape route, fire-resisting doors to bedrooms and kitchens, interlinked alarms across the property and, in larger HMOs, emergency lighting. The exact package depends on the number of storeys and occupants and is agreed with the council and, where relevant, the fire authority. Because these measures shape door positions, lobby layouts and ceiling build-ups, they belong in the drawings from the first sketch rather than being retrofitted after the layout is fixed.
| HMO type | Planning route | Article 4 effect | Licensing |
|---|---|---|---|
| Small HMO (3–6), no Article 4 | Permitted development (C3→C4) | n/a | Often required |
| Small HMO (3–6), Article 4 area | Full planning application | Removes the PD right | Often required |
| Large HMO (7+) | Full planning application | Irrelevant — always needed | Mandatory (5+/2+) |
| Existing lawful HMO | None (already lawful) | n/a | Licence still applies |
Related services: HMO Conversion Drawings, Change of Use Drawings, Planning Permission.
Frequently asked questions
Do I need planning permission to turn my house into an HMO in London?+
What is the difference between a small and a large HMO?+
Is HMO planning permission the same as an HMO licence?+
How do I know if my street has an Article 4 direction for HMOs?+
What is the minimum bedroom size for an HMO?+
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