Sui generis use: what it means in planning
A sui generis use sits outside every class in the Use Classes Order, so the flexibility that lets a shop become an office does not apply. Here is what that means for your site.
Sui generis is Latin for "of its own kind", and in the English planning system it means a use that the Town and Country Planning (Use Classes) Order 1987 deliberately leaves outside every use class. A nightclub, a petrol filling station, a hot food takeaway and a large house in multiple occupation are all sui generis. The practical consequence is blunt: because the use sits in no class, there is no class to move around inside, so any material change into it or out of it is development and needs planning permission.
That single sentence decides a lot of deals. A buyer who assumes a former restaurant can reopen as a takeaway, or that a pub can quietly become a shop, is assuming a flexibility the Order has removed.
What the term means in law
Section 55 of the Town and Country Planning Act 1990 says development includes a material change in the use of buildings or land. The Use Classes Order then takes some of that back. Article 3(1) provides that where a building or land is used for a purpose in a specified class, use for any other purpose in the same class is not development. That is the whole engine of use class flexibility.
Sui generis uses get no such protection. They are either named in article 3(6) as uses that are not included in any class, or they simply do not fit any class description because of their character.
The uses the Order names
Article 3(6) lists the exclusions expressly. The list includes theatres, amusement arcades and funfairs, launderettes, petrol filling stations, scrapyards and breakers' yards, hostels providing no significant element of care, waste disposal installations, retail warehouse clubs, nightclubs, casinos and betting offices.
The 2020 amendment moved a further group out of the old A and D classes and into sui generis territory: public houses, wine bars and other drinking establishments, drinking establishments with expanded food provision, hot food takeaways, cinemas, concert halls, bingo halls, dance halls and venues for live music performance. Those changes took effect on 1 September 2020 and they matter because a great deal of older advice still describes pubs as Class A4 and takeaways as Class A5. Those classes no longer exist.
Houses in multiple occupation sit on a threshold rather than a list. Class C4 covers a small shared house of three to six residents. A house occupied by seven or more unrelated people is sui generis, which is why councils in high-demand student areas argue so hard about resident counts.
How a case officer applies it
An officer asks three questions in order. What is the lawful existing use of the planning unit? Is the proposed use within the same class as that existing use? If either the existing or the proposed use is sui generis, the answer to the second question is automatically no.
The first question is the one that causes trouble. The lawful use is not what the sign above the door says, and it is not what the business rates record says. It is the use that was lawfully established and has not been abandoned or replaced. Where the planning history is thin, evidence matters more than the label: rent statements, staff rotas, licensing records, accounts, dated photographs.
Officers also look at the planning unit itself. A pub with a small hotel element occupying the same unit might be assessed as a single mixed use rather than two separate ones, and a mixed use is itself sui generis.
An illustrative example
Take a vacant unit on a suburban parade, last used as a sandwich shop with a few tables, now proposed as a hot food takeaway opening until 11pm. This example is illustrative rather than a real case.
The sandwich shop sits within Class E, which since September 2020 covers retail, cafes and restaurants, offices, light industry, clinics, nurseries, gyms and indoor sport in one class. The takeaway is sui generis. So the change needs express planning permission, and the application will be judged on odour, noise, litter, late-night activity, parking and any local policy on hot food near schools. A ventilation and extraction statement is usually the document that decides whether the extract system is acceptable, and some councils apply exclusion zones around secondary schools that rule the use out regardless of how good the kitchen design is. We have looked at that policy hurdle in more detail in a separate article on takeaways near schools.
Run the same scenario in reverse and the answer is the same. A takeaway reverting to a cafe also needs permission, because you cannot move out of sui generis for free either.
Where people get it wrong
The most common error is treating "no permitted development right" as "no chance". Plenty of sui generis changes are perfectly acceptable in policy terms and are granted quickly. The Order removes the automatic route, not the prospect of consent.
The second error is assuming the flexibility inside Class E extends to neighbours of that class. It does not. A shop can become an office or a gym without permission because both sit inside Class E, but neither can become a drinking establishment without an application.
Third, people forget that prior approval routes for residential conversion generally depend on a qualifying Class E use. A building in sui generis use cannot use Class MA, and a period spent in sui generis use can break the continuous Class E history that route requires.
And fourth, operational development is a separate question entirely. Even where a change of use needs no permission, a new shopfront, a flue up the rear elevation or an external plant enclosure may each need consent in their own right.
Related terms that are easy to confuse
| Term | What it means | Effect on permission |
|---|---|---|
| Use class | A group of uses listed in the 1987 Order | Movement within the class is not development |
| Sui generis | A use in no class | Every change into or out of it is development |
| Mixed use | Two or more uses in one planning unit with none ancillary | Treated as sui generis in practice |
| Ancillary use | A subordinate use serving the main one | Not a separate use at all |
Ancillary is the distinction worth spending time on. A small trade counter inside a warehouse is ancillary to storage and distribution. Grow that counter until it is drawing general retail customers and it becomes a separate use in its own right, at which point the whole unit may have changed character. Intensification arguments start here.
What to do if your site is sui generis
Start by establishing the lawful use rather than assuming it. If the history is unclear, a certificate of lawfulness for an existing use under section 191 of the 1990 Act is the formal way to fix the position, and a certificate for a proposed use under section 192 confirms that something you intend to do needs no permission.
Then build the application around the reasons the use is excluded from the classes in the first place. Sui generis uses are usually excluded because of their amenity effects, so the evidence base should meet those effects directly. For a late-opening venue that means sound insulation and plant noise. For a filling station it means contamination and highway safety. For a large HMO it means room sizes, amenity space, refuse storage and cumulative concentration in the street.
A short Planning Statement that sets out the existing lawful use, the proposed use, the reason a class change is not available and the policy tests you are meeting will save a validation query. Where a local policy sets a numerical threshold, address the number rather than the principle.
This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. A lawful development certificate is the only formal way to confirm that a use or works are lawful.
Enter your postcode on PlanScope to see which of the 66 reports a change of use on your site 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.
Frequently asked questions
Is a pub still Class A4?
No. The 2020 amendment to the Use Classes Order removed the old A classes in England from 1 September 2020. Public houses, wine bars and other drinking establishments became sui generis, as did drinking establishments with expanded food provision. Older guidance still referring to A4 is out of date, so check the current consolidated Order on legislation.gov.uk before relying on it.
Does sui generis mean permission will be refused?
No. It means there is no automatic right to change the use, so an application is required. The application is then judged on the development plan and material considerations like any other. Many sui generis changes are granted, particularly where the amenity issues that keep the use out of the classes are addressed with proper evidence on noise, odour, hours and parking.
How many people make an HMO sui generis?
Class C4 covers a small house in multiple occupation shared by three to six residents who are not a single household. Occupation by seven or more unrelated residents falls outside C4 and is sui generis. Some councils have also made Article 4 directions removing the permitted change from C3 to C4, so the local position needs checking as well as the national one.
Can a sui generis building convert to flats under prior approval?
Class MA depends on the building having been in a qualifying Class E use, so a building in sui generis use does not qualify. A period spent in a sui generis use can also break the continuous Class E history the route requires. Where the prior approval route is unavailable, a full planning application for change of use is the alternative.
How do I prove the existing lawful use?
Gather dated evidence covering the relevant period: leases, rent records, accounts, utility bills, staff rotas, licensing records and photographs. If the evidence is contested or the history is long, apply for a certificate of lawfulness for an existing use under section 191 of the Town and Country Planning Act 1990. That is the only formal way to settle the point.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.