Which use class is my property?

‘Which use class?’ is a very common question that many ask on a regular basis. This page will hopefully dispel some of the myths and maybe save a few phone calls in the task of answering the question of how to find the use class of a building.

It may fall within Part B, Part C, Class E, Class F1 or Class F2. If it does not fit one of those classes, it may be sui generis or part of a mixed use. So how do you work out which applies?

What is the planning unit?

A use class is normally linked to a planning unit.

Where ‘what use land and buildings have been put to’ is being considered, it is first necessary to determine whether there is a single planning unit or multiple planning units.

Mr Justice Bridge in Burdle v Secretary of State for the Environment [1972] 3 All E.R. 240 it was held that the planning unit is usually the unit of occupation, unless a smaller area can be identified which, as a matter of fact and degree, is physically separate and distinct, and occupied for different and unrelated purposes. The concept of physical and functional separation is key, and Justice Bridge suggested 3 broad categories of distinction:

1. Where it is possible to recognise a single main purpose of the occupier’s use of his land to which activities are incidental or ancillary, the whole unit of occupation should be considered the planning unit
2. Even though the occupier carries on a variety of activities, and it is not possible to say that one is incidental or ancillary to another, the entire unit of occupation should be considered the planning unit, in mixed use
3. Where there are 2 or more physically separate and distinct uses, occupied as a single unit but for substantially different and unrelated purposes, each area used for a different main purpose (together with its incidental and ancillary activities) ought to be considered a separate planning unit

Therefore it is quite possible for ancillary or incidental uses to come within the main planning unit. 

Can the local authority tell me the use class?

The council’s planning history is an important place to start, but there is no definitive national register assigning a lawful use class to every property. A planning officer may give an informal view or pre-application advice, yet that view is only as reliable as the information and evidence available.

Previous permissions, decision notices and approved plans can help, but a permission may never have been implemented and the use may have changed again later. Business-rates descriptions, online directories and commercial apps are also evidence rather than legal proof.

Ask the council for the planning history where it may help, but do not treat an informal telephone answer as a lawful-use determination. Where certainty matters, assemble the evidence and consider a Certificate of Lawfulness of Existing Use or Development.

Okay, so no list – but how can I tell which use class?

To perhaps answer the question of which use class, this is where you need to be a cross between Sherlock Holmes and Miss Marple. You will need to prove it yourself or with the help of your friendly planning consultant.

• What was the building used for when it was open?
• Look at Google Street View and go back in time via the small clock in the top left of the screen. Are there any A boards or other signage that will help? Make a note of the dates
• Look up the building on the Valuation Office Agency (VOA) website – how does that describe the building for business rates? Maybe check more than one year if applicable?
• Ask neighbours to the building – can they help?
• Can you obtain any old leases or other agreements to support your case?
• Did anyone work there – local Facebook groups might help?
• Was it owned by a public body? If so try a Freedom of Information (FOI) request
• Are there any planning applications for a previous change of use? Although note that previous planning on its own is no guarantee as you are not obliged to enact any planning permission

As you can see from the list above, and there may be other sources of information, you may need to be able to prove which use class. If the local authority isn’t keen on the conversion under the GPDO they might be inclined to refuse it as they feel that it wasn’t what you think it was.

I think I now know which use class it is – or do you?!

Great!  However before you submit your application, there are a couple of reasons why it might not be what you think it is!  Is the unit ancillary to another building or another section of the building. A section of offices might actually be B2 because they are ancillary to a factory unit adjoining the offices.

I have known offices to be B2 with no units even close by, because the inspectorate ruled that the offices were ancillary to a unit in another town making pharmaceutical products! If the section can be shown to be a separate planning unit from another part of the building then you may well be fine. This is where a good planning consultant should be able to help.

Where more than one activity takes place, first decide whether one is ancillary to another, whether the property contains separate planning units, or whether there is one genuinely mixed planning unit. A mixed use will usually sit outside a single class and may be described as sui generis. The Use Classes Order contains a specific rule for Class E(g) and B2 uses on one site, or adjacent sites forming one undertaking, provided the B2 area is not substantially increased.

A planning permission may expressly authorise a mixed or sui generis use, so read the description of development and any conditions rather than assuming the Use Classes Order supplies the answer. A change made through Class R is limited to the uses specified by that permitted development right; it does not turn an ordinary office into a sui generis use merely because Class R was used.

Does a long period of vacancy end the lawful use?

Vacancy on its own does not automatically abandon a lawful use, and there is no fixed number of years after which abandonment occurs. It is a matter of fact and degree.

The usual considerations include the physical condition of the building, the length of non-use, whether an intervening use has taken place and the owner’s intentions. A long-closed but readily usable building may retain its lawful use, while a ruin incapable of resuming that use may present a much stronger abandonment case. Demolition can also change the position, but the lawful use of the remaining land and the planning unit still needs to be assessed on the facts.

Where the issue affects a purchase or development proposal, do not rely on vacancy alone. Assemble evidence of the last lawful use and consider whether a Certificate of Lawfulness of Existing Use or Development is appropriate.

Not abandoned, I think I can prove which use class – what now?

Once you have identified the likely lawful use, decide what evidence and application route is needed. A Certificate of Lawfulness of Existing Use or Development (CLEUD) can determine whether an existing use is lawful. A Certificate of Lawfulness of Proposed Use or Development may be suitable where the question concerns a proposed change or activity.

Eek!  I still need help…..

Still confused as to which use class? No worries – book a session with Ian, the founder of Planning Geek and he will assist you via Zoom on both the building and also what you can do with it. You can book a session via this page.

Which Use Class Page Updated: 24th August 2026

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