What single household means in Class C3

Class C3 of the Town and Country Planning (Use Classes) Order 1987 turns on the phrase "single household", and the phrase does not mean what most landlords assume. Three friends sharing a house are not a single household. Two of them plus one of their brothers are not a single household either. The definition borrowed from housing law is narrow, and getting it wrong is how a C3 let becomes an unauthorised change of use to Class C4 or to a sui generis large HMO.

Getting it right is mostly a matter of reading two sections of the Housing Act 2004 alongside the Use Classes Order.

The three limbs of Class C3

C3 covers dwellinghouses, and it has three parts.

C3(a) is use by a single person, or by people to be regarded as forming a single household.

C3(b) is use by not more than six residents living together as a single household where care is provided to residents.

C3(c) is use by not more than six residents living together as a single household where no care is provided, which picks up small group homes and similar arrangements that are not families but do live communally.

All three limbs carry the same qualifier. If the occupiers do not form a single household, none of the limbs apply, and the use is either Class C4 or something outside the Order entirely.

Class C4, added in 2010, covers a small house in multiple occupation occupied by between three and six unrelated individuals sharing basic amenities, taking the meaning of an HMO from section 254 of the Housing Act 2004. Above six sharers the use is sui generis and needs planning permission in its own right.

What counts as a single household

Section 258 of the Housing Act 2004 does the work. Persons are treated as forming a single household only if they are all members of the same family, or if their relationship falls within a category prescribed by regulations.

Same family means one of three things. The occupiers are married, in a civil partnership, or living together as if they were. One is a relative of the other. Or one is a relative of a person within the first category. Relative is defined to include parent, grandparent, child, grandchild, brother, sister, uncle, aunt, nephew and niece, including step-relations and half-blood relations.

The prescribed relationships added by regulations pick up a small number of live-in arrangements such as domestic staff and carers employed by a member of the household.

Everything else falls outside. A couple and the sister of one of them are a single household. A couple and their friend are not. Three postgraduate students on a joint tenancy who cook together every evening and describe themselves as a household are not, because the test is relationship, not lifestyle.

That is the point landlords most often get wrong, and it is worth saying plainly. Behaviour does not create a household. Family relationship does.

Where two sharers sit

Two unrelated people sharing a house sit in a gap, and the gap is useful.

Section 254 defines an HMO by reference to occupation by persons forming more than one household, and the standard test requires three or more occupiers. Two unrelated sharers therefore do not create an HMO, so Class C4 cannot apply, and councils generally treat the property as remaining within Class C3. The Order itself does not say so in terms, and the reasoning is not free of doubt, so check the position with the local planning authority before building a business on it.

The practical consequence is straightforward. Moving from a family let to a two person sharer let is rarely a material change of use. Moving from two sharers to three is the step that engages Class C4 and, in an area with an Article 4 direction, engages the need for planning permission.

Care, support and the line with Class C2

C3(b) and Class C2 look similar on paper and are argued about constantly. C2 covers residential institutions, including residential care homes and hospitals. C3(b) covers up to six residents living together as a single household with care provided.

Whether residents live together as a single household is a matter of fact and degree. Inspectors look at whether meals are taken communally, whether the property is the residents' home rather than an institution, how staffing is arranged, whether staff sleep in, how long residents stay and how much of daily life is shared. A supported living scheme for four adults with learning disabilities, run in an ordinary house with waking night cover, will often be C3(b). The same building run as a registered care home with 24 hour clinical staffing and high turnover looks like C2.

Seven residents changes the analysis whatever the care arrangements, because both C3(b) and C3(c) cap at six.

Where a scheme sits close to the line, a pre-application enquiry with a short written description of the operating model is the quickest way to find out. If permission is needed, a planning statement that sets out the staffing model, the tenure arrangements and the daily routine gives the officer something to assess other than the floor plan.

What the council will actually look at

Evidence beats assertion. When an officer investigates whether a C3 use has slipped into C4 or beyond, they look at the same short list every time.

• The tenancy structure: one joint tenancy naming all occupiers, or separate room-only agreements with individual start dates.
• The council tax and licensing position, including whether an HMO licence has been granted under Part 2 of the Housing Act 2004.
• The layout, particularly locks on bedroom doors, en suites added to bedrooms, kitchenettes, and whether the communal living room has been converted to a bedroom.
• Bin provision, cycle storage and the number of cars on the frontage, which is how neighbours notice first.
• Marketing material, which is often the clearest evidence of all.

Losing the only communal living room is the single most reliable indicator that a house has become an HMO in planning terms, and it is the detail that shows up on drawings submitted for an entirely different application.

Illustrative example: a landlord converts the ground floor reception room of a three bedroom terrace into a fourth bedroom and lets all four rooms on separate agreements. No building work needed permission. The change of use from C3 to C4 did, in an Article 4 area, and the drawings submitted later for a rear extension are what alerted the enforcement team.

Changing between C3 and C4, and back

Part 3 of Schedule 2 to the GPDO 2015 permits change of use from C4 to C3, and from C3 to C4, without a planning application. Many councils have removed the C3 to C4 direction of that right by Article 4 direction, typically in university towns and areas with concentrated shared housing, so the first check on any acquisition is whether a direction covers the address.

Going above six occupiers is a change to a sui generis use and always needs permission. Expect the council to ask for amenity standards, refuse and cycle storage, and parking evidence. Where on-street parking is under pressure, a parking survey carried out to a recognised methodology carries far more weight than an assertion that tenants will not own cars.

On enforcement, do not rely on the old four year rule for changes of use. The Levelling-up and Regeneration Act 2023 moved enforcement time limits in England towards a single ten year period, so check the current position and the commencement date before assuming a historic use has become immune.

This is general guidance rather than legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

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