Composite and mixed uses on one site

If your premises do two things at once, the planning answer depends on whether one of them is subordinate to the other. A café with a small takeaway counter is probably a café. A unit where half the floor area and most of the evening trade is takeaway is probably a composite use, and a composite use sits outside the Use Classes Order altogether. That single distinction decides whether you can change what you do without planning permission.

The starting point is the planning unit: the parcel of land and the activity on it that planning law treats as one thing. Get the unit wrong and every conclusion that follows is wrong too.

The planning unit comes first

The approach courts take, set out in the well-known judgment in Burdle v Secretary of State for the Environment, works through three situations.

Where an occupier uses the whole of their unit for one main purpose, with other activities that are incidental or ancillary to it, the whole unit is the planning unit and its use is the main purpose. The ancillary activity does not need its own permission.

Where two or more physically separate and distinct areas are occupied for substantially different and unrelated purposes, each area is its own planning unit with its own use.

And where there is a variety of activities within one unit, none of which is ancillary to another, the whole unit is the planning unit and its use is composite.

The second situation is a question of fact: separate entrances, separate tenancies, separate staff, physical division. The third is a question of degree, and it is where the arguments happen.

Ancillary, or a second primary use

Nothing turns on what you call it. Officers look at the facts, and the facts they look at are consistent.

Floor area given to each activity. Turnover split. Staff numbers and the hours they work. Opening hours for each activity, and whether one continues after the other stops. Separate advertising and separate signage. Deliveries and servicing attributable to each. Customer numbers and how they arrive.

An activity stays ancillary while it remains clearly subordinate and functionally linked to the main use. A gym with a small protein bar for members is a gym. The same gym with a street-facing juice bar open to the public until late is running two uses, and the second one has its own highway, noise and amenity consequences that the authority will want to assess.

There is no numeric threshold. Anyone offering you one is guessing. What you can do is document the balance, because the evidence is what any later argument will turn on.

Why a composite use is sui generis

The Town and Country Planning (Use Classes) Order 1987, as amended in 2020, puts most commercial activity into Class E, which covers retail, cafés and restaurants, financial and professional services, indoor fitness, medical and health services, crèches and nurseries, offices, research and development, and light industrial processes that can be carried out in a residential area.

Movement between those sub-categories is not development, which is the flexibility Class E was created to deliver. A shop can become an office or a clinic without an application.

A composite use does not sit in Class E, or in any other class. It is sui generis, which means every change of use to or from it is potentially development requiring permission. That cuts both ways and the downside is usually the one that bites: a sui generis mixed use has no permitted change rights, so you cannot move within Class E even for the part of your business that would qualify on its own.

Several uses are sui generis without being composite, including hot food takeaways, drinking establishments, cinemas, theatres, nightclubs, laundrettes, petrol filling stations, betting offices and casinos. Mixing one of those with a Class E activity produces a composite use almost by definition.

Changing the balance is a change of use

Where you hold a permission for a mixed use, the permitted use is the mix as described. Changing the proportions can be a material change of use even though both activities were already happening.

That is the trap in practice. An occupier who grows the takeaway side of a restaurant from a quarter to two thirds of the business has not added a new activity, and they may well have made a material change of use requiring permission. Whether it is material is a matter of fact and degree, judged on the character of the use and its effects.

Intensification works the same way. More covers, longer hours, delivery riders arriving through the evening and additional extraction all change the character of what is happening, and the authority assesses the effect rather than the label.

If you are planning to shift the balance deliberately, apply. A Planning Statement setting out the existing lawful use, the proposed balance and the effects on amenity, parking and servicing is a modest document that prevents an expensive argument later.

Proving your existing lawful use

You cannot argue about a change from a baseline you cannot establish. Assemble the evidence before you need it.

Useful material includes the original planning permission and any conditions, previous Lawful Development Certificates, business rates records, leases and licences, dated photographs of the shopfront and interior, accounts showing the turnover split, staff rotas, delivery invoices, premises licences and environmental health registrations.

Where the position is unclear, a Lawful Development Certificate for an existing use under section 191 of the Town and Country Planning Act 1990 is the only formal way to establish it. It is worth the fee on any premises where the use has evolved over years and nobody has ever written down what it became.

Conditions that come with a mixed use permission

Permissions for composite uses are almost always conditioned, and the conditions are where the commercial constraints actually live.

Expect limits on the floor area given to each element, restrictions on opening hours by element, delivery and servicing hours, a requirement for an approved extraction and odour control scheme, waste storage arrangements, and sometimes a restriction on the number of covers or on external seating.

Read the extraction condition carefully. For any food use the ventilation and odour position is normally dealt with by a Ventilation and Extraction Statement submitted either with the application or at discharge stage, and the specification has to match the kitchen you are actually installing.

Two drafting points are worth raising at the time rather than later. A condition that fixes a floorspace split by reference to a named drawing is easier to live with than one expressed as a percentage of an undefined total. And a condition allowing the balance to be varied by written agreement without a further application is a tailpiece, which the courts have treated as unlawful in the circumstances explained in tailpiece conditions and why they are unlawful.

Most of these conditions have to be satisfied before trading begins rather than before building work starts, so they belong on the schedule alongside the conditions you must discharge before work starts. Fitting out a kitchen and then discovering the extraction scheme has not been approved is a common and avoidable delay.

The practical sequence

Work out what your planning unit is. Work out whether each activity is ancillary or primary, with evidence. If the answer is composite, accept that you are sui generis and that changes need permission. Then decide whether to apply for the use you actually want, rather than the one your premises happen to have drifted into.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

Enter your postcode on PlanScope to see which documents a change of use application at your premises is likely to need. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.