Amenity in an HMO conversion: light and space

Converting a house to a house in multiple occupation puts you in front of two separate regimes with different standards for the same rooms. Planning assesses amenity for future occupiers and for the surrounding area. HMO licensing under the Housing Act 2004 sets mandatory minimum room sizes and condition standards. The licensing minima are floors, not targets, and a council's planning policy frequently asks for more. HMO conversion amenity standards are where applications fail, usually on a small rear bedroom that satisfies the licence and not the local plan.

Work out which standard is higher for each room before you draw the layout.

Amenity standards applied to houses in multiple occupation

Many authorities publish a supplementary planning document for HMOs, and where one exists it is the document officers apply. Typical contents are a minimum room size schedule by occupancy, a communal living space requirement expressed per occupant, a minimum provision of external amenity space, refuse and recycling storage capacity, cycle parking, and sometimes a requirement that a communal living room be retained rather than converted into a let room.

That last requirement defeats more schemes than any other. A six bedroom HMO created by converting the front reception room into a bedroom will often be refused where the policy requires a shared living space in addition to the kitchen.

Whether you need permission at all depends on scale and on whether an Article 4 direction applies. A change from a single dwelling to a small house in multiple occupation for three to six people is permitted development under Part 3 of the General Permitted Development Order unless a direction has removed that right, which many university towns and cities have done. Seven or more occupiers is a larger HMO outside the use classes, and that always needs permission.

Room sizes and the licensing overlap

The mandatory licence conditions set minimum sleeping room floor areas: 6.51 m2 for one person aged over ten, 10.22 m2 for two people aged over ten, and 4.64 m2 for a child under ten. Floor area below 1.5 metres in height does not count towards those figures, which matters in a loft room.

Set the two schedules side by side. A room of 7 m2 is lawful for one occupier under the licence and may fall short of a planning policy asking for 8 or 9 m2 for a single let room. Design to the higher figure and both are satisfied. Design to the licence minimum and you may hold a licence for a property you cannot lawfully use as proposed.

Natural light to each let room

Every let room needs a window to the outside air, and officers assess whether the light is adequate rather than simply present.

The rooms that cause problems are predictable. A basement or lower ground room with a lightwell. A rear room lit only through a deep single storey extension. An internal room created by subdividing a larger one, with a borrowed light or a high level window. A loft room lit by a single small rooflight.

Where a room is marginal, a calculated assessment carries far more weight than a statement that the room has a window. A Daylight and Sunlight Assessment applying the recognised internal method, reported room by room, is what an officer can rely on. Basement rooms need particular care, and the approach is set out in our note on daylight assessment for a basement conversion.

Ventilation sits alongside light. Each room needs background ventilation and a means of purge ventilation, and a window that is restricted for fall protection may not provide the openable area assumed. The same drawing that proves the light should prove the opening.

Shared amenity space and bin storage

Shared facilities are assessed on capacity rather than presence.

• Kitchen provision scaled to the number of occupiers, with worktop length, hob rings, sink and fridge capacity usually specified in local standards.
• Bathroom and WC provision per occupier, with the ratio set by the licensing standard.
• A communal living space in addition to the kitchen where policy requires it, with a minimum area per occupier.
• Refuse and recycling storage sized to the collection frequency and the number of occupiers, within the drag distance the waste authority allows.
• Secure cycle parking, which in urban areas is often required at one space per occupier.
• Usable external space, with the rear garden retained rather than wholly given over to bin and cycle storage.

Bin storage is the detail that produces objections from neighbours, because an HMO generates more waste than the household it replaced and the bins end up at the front. Show the store, its capacity and the route to the collection point on the application drawings, not in a paragraph.

Noise and disturbance within the building

Internal noise between let rooms is a planning and a licensing consideration, and it is also the thing that generates complaints to the council after conversion.

The standard expectation is upgrading separating walls and floors between let rooms, though planning policy rarely specifies a figure. Where a council does set one, it is usually expressed as a sound insulation performance between rooms rather than the dwelling standard applied between flats. Building Regulations requirements on a material change of use apply separately, so confirm the position with building control at the outset.

Practical measures that officers recognise: resilient layers under new floor finishes, acoustic plasterboard with an independent lining to party walls between rooms, solid core doors with seals, and locating a kitchen away from a bedroom below. External noise matters too where the property is on a main road and windows must stay closed.

Where planning and licensing differ

The two regimes answer different questions, and conflating them causes most of the confusion.

Planning asks whether the use is acceptable in that location: the concentration of similar uses in the street, parking stress, amenity for future occupiers and the effect on neighbours. Licensing asks whether the property is safe and adequately equipped for the number of people living in it. Planning permission does not guarantee a licence, and a licence does not make an unauthorised use lawful.

They also sit with different teams on different timescales. A licence application is dealt with by the private sector housing team and a planning application by development management, and neither will tell you what the other requires. Where parking stress is in issue, a survey carried out to a recognised methodology is the evidence that counts rather than an assertion about local conditions.

Documents for the application

A conversion application that gets validated and determined without a request for further information contains the following.

1. Existing and proposed floor plans at 1:50 or 1:100, with every room labelled, its use stated and its floor area given.
2. A room schedule listing each let room, its area, the area above 1.5 metres in height, its window area and its proposed occupancy.
3. A comparison of each room against both the licensing minimum and the planning standard, with the policy reference.
4. A plan showing communal space, external amenity space, bin store and cycle store with capacities.
5. A daylight assessment for any marginal room.
6. A management plan covering waste, noise and the letting arrangement.
7. A parking survey where the policy requires one or where parking stress is likely to be raised.

A Planning Statement pulling those threads together against the relevant policies is worth the effort on a contested application, and internal daylight evidence should follow the method described in our note on internal daylight assessment.

And check for an Article 4 direction first. In many towns that single check determines whether you are making an application at all.

Enter your postcode on PlanScope to see which reports a conversion is likely to need.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.