How to adapt corporate space without falling foul of planning rules

Planning permission is needed when ‘development’ takes place. Development is defined by statute as being operational (physical) works and a material change in the use of land, even where no construction work is proposed.

You should therefore think in two boxes: physical works and changes of use. First, operational works (for example, building, engineering or other physical works), and separately, a material change of use of land or premises. If what you are planning falls into either box, permission may be needed unless a specific exemption applies or works are so minor as to be inconsequential.

The only way to achieve 100% certainty that a current use is lawful if there is no planning permission is to obtain a Certificate of Lawfulness of Existing Use or Development. This requires an application to the local council (planning authority) with detailed and corroborated evidence that the specific use of a defined area of land has been undertaken for a continuous period of ten years. The burden of proof is on the applicant on a greater than 50% probability.

This is a legal process, where the evidence will be scrutinised closely. However, the planning merits of the use are not under consideration as they would be for a planning application. Proving the factual position that the same use has continued within the stated site boundary for ten years is the objective. When a Certificate of Lawfulness is granted for a particular use, no enforcement action can then be taken concerning that use.

A ‘material change of use’ means the character of how the land or building is used has changed in a way the planning system considers significant. In plain terms, it is not just ‘what’ you do, but the real-world impacts it creates. What counts as ‘material’ is not defined in legislation and is assessed as a question of fact and degree, informed by what is happening on the ground and by case and appeal decisions. An intensification of an existing use can amount to a material change that requires permission.

The general rule is that internal changes don’t need planning permission. However, internal work can still trigger the need for planning permission. A mezzanine floor, although wholly internal, may need planning permission in a retail setting, or where a planning condition or Section 106 obligation (legal agreement) restricts mezzanines or total floorspace.

For example, a shopping centre may lend itself to additional internal floorspace at mezzanine level but already be providing the maximum retail floorspace permitted by planning condition. Even where there is no floorspace condition, a building used for retail cannot be increased by more than 200 sq. metres of gross floorspace. In both cases, a planning permission would be required.

Any works to a listed building (external or internal) that affect its character as a building of special architectural or historic interest require Listed Building Consent, quite separately from any need for planning permission. Internal alterations are not exempt and need to be assessed as to whether listed building consent is required.

Permitted development (PD) rights are a shortcut, where legislation grants permission for certain works without a planning application. The Town and Country Planning (General Permitted Development) (England) Order 2015 (as amended) also grants permission for certain changes of use between use classes, though many require a prior approval process with the local authority.

PD rights can be removed by planning condition or by a local planning authority process which covers a defined area, known as an Article 4 Direction, in which case a full planning application is needed. A common Article 4 direction affects landlords, where the right to use a family dwellinghouse as a House in Multiple Occupation is removed and so planning permission must be obtained for such change of use.

Many business uses sit within legally defined ‘use classes’. If the existing and proposed uses are both within the same use class, the change is not ‘development’ and can be made without planning permission.

The Town and Country Planning (Use Classes) Order 1987 (as amended) specifies these use classes, including Class E (commercial, business and services), Class B2 (general industrial) and Class B8 (storage and distribution). The Class E use is wide ranging, but interpretation needs care.

Uses that do not fall within a defined class are ‘sui generis’, meaning ‘a class of their own’; any change to or from a sui generis use will require planning permission. Examples of sui generis uses include hot food takeaways, scrapyards, petrol filling stations, car showrooms and pubs, and potentially premises used for example as business centres or data centres where a bespoke mix of uses does not fit a class.

Examples of lawful use classes and relevant permitted change of use are given below from the 2021 amendments to the Permitted Development Rights Order 2015. Check the full Order as to whether a PD route exists and whether prior approval is required. Then confirm that there are no planning conditions or obligations, or Article 4 Directions removing PD on your site.

If you need planning permission, plan early and instruct reports to support the case. Councils decide change-of-use applications against policy and site-specific impacts. Key considerations include the Local Plan policy position, which is the legal starting point for the decision – applications should be determined in line with the plan policies unless material considerations indicate otherwise.

‘Material considerations’ include neighbour impact (e.g. overlooking, noise, hours, traffic and amenity), highways and parking, design and appearance of any external changes, heritage impact, environmental matters such as flood risk and contamination, and the site’s planning history and appeal decisions. All bases should be covered within the planning application, particularly if an appeal against refusal may be needed. The majority of appeals are by written representations and under new Regulations from 1 April 2026 usually no extra materials can be added to strengthen the appeal case.

You should:

• Check the lawful use class and planning history of the site.
• Understand relevant permitted development rights.
• Review planning conditions and any Article 4 Directions that may remove PD rights.
• Seek Listed Building Consent where character of the building or its setting may be affected
• Check Building Regulations requirements.
• Obtain specialist advice where uses are complex or unclear.

You should not:

• Assume minor works are exempt; check first.
• Ignore planning conditions or restrictions in section 106 agreements.
• Overlook the need for express permission for external works if no PD rights apply.
• Rely on assumptions; always verify the lawful position.

Potential consequences of non-compliance include enforcement action, disruption to trading and costs to regularise unauthorised development.

Before making any change, identify your current lawful use, define your proposed use, and check whether the change is within the same use class, a permitted development route, or requires full permission. What physical works are needed to the premises and will planning permission be required? Where there is any doubt, take early advice, gather evidence, and consider a Certificate of Lawfulness to lock down your position. Remember that PD rights may be limited by planning conditions, legal agreements or Article 4 Directions, and that listed buildings may need listed building consent.

If you would like to discuss anything we have covered in this article, or if you want to find out more about how we can support you, please don’t hesitate to get in contact with a member of our team.