HMO Room Sizes and Standards in London: Rooms, Kitchens, Fire and Building Regulations

HMO room sizes: the national minimum and the London standard

The national figures are licence conditions under Schedule 4 of the Housing Act 2004. They apply to every licensed HMO in England. Measure wall to wall, and leave out any floor under a ceiling lower than 1.5 m.

These are floors, not targets. London boroughs publish their own HMO standards, and most set bigger rooms. The deciding question is whether the house keeps a shared living room.

What three London boroughs ask for

We read three published standards: Camden (effective 8 December 2020), Hounslow (May 2018) and Southwark (adopted July 2015). Each one sets a smaller bedroom where the residents share a living room, and a bigger one where they do not.

Doubles follow the same pattern. Without a shared living room, Camden asks for 11 m², Southwark 14 m² for a couple, and Hounslow more than 12 m².

How the inspector measures

The details move the numbers as much as the headline figures. Southwark does not count kitchens, bathrooms, corridors or chimney breasts. Hounslow leaves out chimney breasts, lobbies and bathrooms. Camden deducts the space for any basin or shower inside the room.

Ceiling height matters too. Hounslow asks for at least 2.14 m over 75% of the floor, and Southwark 2.3 m over at least half. Camden and Hounslow allow no more than two people in any room, however large.

HMO kitchen and bathroom requirements per person

The national rules ask only for facilities that are adequate for the number of people sharing. That is Schedule 3 of the 2006 HMO licensing regulations. Boroughs turn "adequate" into numbers, and the numbers decide how many kitchens and bathrooms your layout needs.

All three standards we read share one ratio: one set of kitchen facilities for every five people. A set means a sink and drainer, a cooker, worktop, cupboards, fridge and freezer space, sockets and bins.

Camden asks for more where the kitchen is also the dining room. That means 8 m² for up to five people and 15 m² for six to ten. It also wants 500 mm more worktop for each extra person, so 2.8 m for five.

Where the kitchen sits

Location is a standard too. Hounslow wants the kitchen no more than one floor from each letting room, or a dining area beside it. It also says a kitchen must never be the only way into a bedroom.

Bathrooms and WCs

Bathrooms follow the same five-person logic, with one difference that catches layouts out. At five people, Camden and Hounslow want a WC in its own compartment, not only inside the bathroom.

En-suites count in your favour: Hounslow leaves residents with their own facilities out of the shared count. But Camden and Southwark both warn that rooms with their own kitchen and bathroom become self-contained. That can need planning permission.

HMO fire regulations: LACORS, fire doors and the alarm system

Fire safety in an existing HMO is judged against the LACORS housing fire safety guidance of July 2008. Councils use it when they license and inspect. Camden's standard, for example, requires fire works to follow LACORS and BS 5839-6, the alarm standard.

The guidance does not cover a building converted to the Building Regulations of 1991 or later. So a full conversion is designed to Part B, and LACORS is what the inspector checks it against later. Design for both and you only build it once.

The precautions scale with the type of HMO and the number of storeys.

Grade D means mains alarms with battery back-up, interlinked. LD3 covers the escape route only; LD2 adds the rooms where a fire is likely to start. Grade A is a panel system.

HMO fire door regulations in practice

There is no separate fire door law for HMOs. The rules come from the LACORS guidance, the licence conditions and Part B. FD30 means 30 minutes of integrity; the S adds smoke seals.

These are the fire door details the guidance sets:

1. Self-closers. Needed in most multi-occupied houses, and always on the entrance door to a bedsit.
2. Whole doorsets. A tested door and frame together is preferred to upgrading an old door, except where a listed building needs it.
3. Installation. Fitted and maintained to BS 8214, with the intumescent strips the test report specifies.
4. No inner rooms. A bedroom reached only through a kitchen or lounge should be avoided wherever possible.

HMO Building Regulations: when a conversion is a material change of use

Planning, licensing and Building Regulations are three separate tests. A house can pass the first two and still fail building control.

Regulation 5 of the Building Regulations 2010 sets the test. A change of use is "material" when the building gains a flat, more dwellings, or rooms for residential purposes. A room for residential purposes is a room someone lives and sleeps in that is not a house or flat. Hostels and boarding houses are the named examples.

Whether a shared house falls in that definition is a judgement for building control, so ask at design stage. Bedsits and self-contained units are the clearest cases.

What a material change of use triggers

Regulation 6 then lists the requirements the converted building must meet. In every case these are:

1. Fire safety. Part B1 to B5: means of warning and escape, linings, structure, roofs, and access for the fire service.
2. Ventilation. Part F1 for every room.
3. Water and sanitation. Part G1 and G3 to G6: cold and hot water, WCs, bathrooms and kitchens.
4. Drainage and waste. Part H1 foul drainage and H6 bin storage.
5. Energy and electrics. Part L1 for energy and Part P1 for electrical safety.
6. Combustion appliances. Part J1 to J4 for boilers and flues.

Sound insulation (Part E) is added where the conversion creates flats, more dwellings or rooms for residential purposes. Walls and floors between those rooms must reach 43 dB of airborne sound insulation, and floors must keep impact sound to 64 dB or less. These are the Approved Document E values for a change of use.

They are tested on site, and the results go to building control.

Even without a material change of use, most HMO work is building work anyway. Structural openings, new bathrooms and drainage, and a rewire all need sign-off under regulation 3. Plan for building control from day one.

Planning comes first of all. A house can become a small HMO for up to six residents under Class C4. Seven or more is sui generis and needs full planning permission, and many boroughs have removed the C4 right with an HMO Article 4 direction.

Design the HMO layout in this order

Most failed layouts were drawn in the wrong order: bedrooms first, standards last. This sequence keeps the room count you paid for.

1. Get the borough's current standard. Room sizes, kitchen and bathroom ratios, and any planning policy on self-contained rooms.
2. Fix the headcount. Up to six residents or seven and more decides the planning route, the kitchens and the bathrooms.
3. Draw the escape route. Every bedroom opens onto it, no inner rooms, fire doors on every risk room.
4. Decide on the living room. Keep it and bedrooms can be smaller; lose it and every bedroom grows.
5. Place kitchens and bathrooms. One set per five people, within a floor of every room, WC separate at five.
6. Specify fire and sound separation. The protected route, the alarm grade, and 43 dB walls and floors where Part E applies.

As an illustration of the arithmetic, take six people in Southwark without a shared lounge. Each single room needs 10 m². Two sets of kitchen facilities are needed, and a kitchen for ten users must be at least 14.5 m². Two bathrooms, two WCs and two basins follow.

On our 2026 rates, construction only and ex VAT, light HMO works with the layout kept run at £1,040 to £1,300 per m². A reconfigured house with en-suites is £1,400 to £1,750, and a full conversion £1,760 to £2,200. Our HMO conversion page has the calculator.

The licence is the last step, not the first. Our guide to HMO licence and regulations covers the application, the fees and the certificates.

How we design an HMO to pass the first inspection

We take on HMO conversions as one design and build contract, from the route check to handover. Construction starts from £100,000, so our fit is a whole-house conversion, a building becoming an HMO, or a portfolio.

Craftex started in 2016 as a carpentry and joinery company, and around 60% of our labour is still in-house. Fire doorsets, linings and partitions are our own trades, not a chain of subcontractors.

Send us the address and the floor plans, and get a free HMO route check. You hear which consent the house needs, how many rooms it holds and what the standards will cost to build.

Before you buy or draw anything, check these points against the house: