HMO room sizes and amenity standards in Wales

Cardiff landlords applying for an HMO licence must satisfy the council that the property is suitable for the number of occupiers. Unlike England, which introduced nationally prescribed mandatory licence conditions in 2018, Wales has no equivalent national regulation setting minimum floor areas. The Welsh Government's guidance leaves room size assessment to each local authority, which means the applicable figures vary across Wales and cannot be read from any single national instrument. For Cardiff, the source is the council's own HMO Licensing Fire Safety and Amenity Standards document, updated September 2022, and it is the figures in that document that Cardiff licensing officers apply when processing applications for both mandatory and additional licences.

For a complete picture of when licensing is required in Cardiff and how the mandatory and additional schemes work alongside each other, see our guide to HMO licensing in Wales. This article focuses specifically on the physical standards that Cardiff applies once a property falls within a scheme: minimum bedroom floor areas, shared kitchen and bathroom requirements, and how those figures are applied in practice. An interactive room size checker at the foot of the article lets you calculate whether a proposed bedroom meets Cardiff's standard before you submit an application or begin a conversion.

No national standard: why the figures vary across Wales

Several secondary property sources attribute specific bedroom dimensions to a Welsh order or regulation. One common version cites the Licensing of HMOs (Prescribed Description) (Wales) Order 2006 for room sizes. That Order defines which HMOs require mandatory licensing in Wales. It contains no floor area figures whatsoever. The room sizes that appear alongside that citation are in fact the England mandatory licence conditions introduced in 2018 and have no standing in Wales. Cardiff does not use them, has never adopted them, and applying them to a Cardiff application will produce the wrong answer. The Welsh Government's position is that suitability for occupiers is a local authority judgement, which is why Cardiff's published document is the correct starting point for any Cardiff HMO, and why a landlord licensing in Swansea or Newport would need to check those councils' standards separately.

The condition that changes everything: is there a separate living room?

Cardiff's figures for bedroom minimum sizes are not a single number. They depend on one condition: whether the property provides a separate living room as a communal space for residents. This conditional is the part that general UK property guidance consistently omits, and its omission leads landlords to apply the wrong figure in the majority of Cardiff shared houses.

Where a separate living room is provided, residents have somewhere to study, eat and relax outside their bedroom, so the bedroom itself is assessed against a lower minimum. Where no living room is provided and the bedroom is the only private space available to the occupier, a larger minimum applies to compensate. Cardiff Council's guidance makes this distinction explicit, and officers assess each property against whichever configuration applies to it.

Only usable floor area counts. Areas under approximately 1.5 metres of ceiling height are typically excluded. Cardiff's published examples are described as a guide, and the council acknowledges that alternative layouts may be acceptable, but any room that falls short of the stated minimum will need specific justification at application stage and may not be approved.

Shared kitchen and amenity standards in Cardiff

Bedroom floor areas are only part of what Cardiff assessors check. The same September 2022 document sets out minimum requirements for the shared spaces and facilities that HMO occupiers use in common. For kitchens, the minimum is 7 square metres for up to six occupants, with an additional 2.5 square metres required for each occupant beyond six. A shared living room, where provided, must be at least 11.5 square metres for up to six occupants.

Bathroom and toilet provision is set by occupancy ratios rather than fixed floor areas. Cardiff requires one bathroom for every five occupants, and one WC for every four occupants (or one per five where the WC is in a separate compartment). There is no minimum bathroom floor area in the Cardiff document: the requirement is that there is sufficient space to wash, change and dry. One sink per five occupants and two linear metres of worktop per five occupants round out the kitchen amenity requirements. All figures are from the same HMO Licensing Fire Safety and Amenity Standards document and apply to both mandatory and additional licensed HMOs in Cardiff.

Cathays and Plasnewydd: additional licensing, same standards

Cathays and Plasnewydd are subject to Cardiff's additional HMO licensing scheme, which captures smaller properties that do not reach the threshold for mandatory licensing. Landlords operating in those wards sometimes assume that additional licensing carries different or lighter physical standards. It does not. The HMO Licensing Fire Safety and Amenity Standards document applies to both schemes, and officers assess additional licensed properties against the same room size and amenity figures as mandatory ones. The practical difference between the two schemes is the range of properties required to hold a licence, not the standards applied once a licence is sought. For more on Cardiff's HMO concentration rules and the planning position in these wards, see our article on HMO fire safety compliance in Wales, which covers the connected fire safety requirements that apply in tandem with these amenity standards.

Planning and building control: separate requirements

A Cardiff HMO conversion that requires planning permission faces assessment under two separate regimes. Licensing standards govern whether the council will grant a licence once the building is in use as an HMO. Planning and building regulations standards govern whether the conversion itself is acceptable and may require consultation with Cardiff's planning officers before work begins. Building regulations Part M (accessibility) and the Nationally Described Space Standard, where it is applied as a planning condition, can impose minimum dimensions that differ from the licensing figures. Where the two sets of requirements conflict, the more demanding standard effectively governs the design. Our step-by-step guide to converting a Cardiff house to an HMO covers the planning permission process and the sequencing of consents in more detail.

How Cardiff applies these standards in practice

Cardiff's published figures are explicitly described as a guide. The council states that alternative layouts may be accepted, which gives licensing officers some discretion where a room falls slightly short but the overall property is otherwise suitable. In practice, a room that meets the relevant minimum is unlikely to attract a refusal on size grounds. A room that falls short will need the landlord to demonstrate that the shortfall is offset elsewhere in the property, and that outcome is not guaranteed. The safest approach at design stage is to build to the applicable standard rather than plan around the discretion. For landlords appraising a purchase with existing room layouts, the interactive tool below gives an immediate read on whether each room clears the Cardiff benchmark, which informs the pre-purchase negotiation and the refurbishment budget.

Cardiff licensing officers also have the authority to impose additional conditions on a specific HMO licence where the property's layout warrants it, for instance requiring a larger minimum than the published figure where local circumstances make that reasonable. Conditions imposed on renewal may differ from those on the original grant, particularly if amenity standards or council policy have been updated in the intervening period. For a broader view of the compliance landscape for Cardiff HMO landlords, our 2026 HMO investment guide sets these requirements in the context of deal appraisal and return on investment.