"Sui generis," a Latin term meaning "of its own kind," is used in planning to describe properties or land uses that don’t fit into any specific category defined by standard use classes. These use classes are outlined in the Town and Country Planning (Use Classes) Order 1987.
In the UK planning system, every type of building or land use is generally classified under a specific "use class" as outlined by the Town and Country Planning (Use Classes) Order 1987. However, some uses don't comfortably fit into any of these predefined categories. These are known as "Sui Generis," a Latin term meaning "of its own kind."
Sui Generis Planning Usage applies to these unique cases and plays a critical role in determining whether planning permission is required for a change in use. Unlike uses within the same class that can often be changed under permitted development rights, Sui Generis uses almost always require full planning permission. This guide explores the intricacies of Sui Generis Planning, the types of properties affected, the process of gaining permission, and how to ensure a successful outcome.
Definition
"Sui Generis" refers to uses that stand alone and do not fall under any other use class. As the planning landscape evolves with the needs of modern society, more and more land uses fall under this category.
Legal Framework
Sui Generis uses are governed by the Town and Country Planning (Use Classes) Order 1987 (as amended), which separates different land uses into classes for administrative ease. Changes within the same class often do not require planning permission, but Sui Generis Planning Usage is excluded from this flexibility.
Some of the most frequently encountered Sui Generis uses include:
Each of these uses is considered to have a significant impact on the local environment or community, warranting individual assessment under planning regulations.
The threshold at which an HMO becomes Sui Generis is crucial for landlords, developers, and investors to understand. It often dictates whether a simple conversion can proceed under permitted development rights or requires a full planning application.
When planning a conversion to a large HMO under Sui Generis Planning Usage, consider:
Unlike standard use classes, moving to or from a Sui Generis use always requires formal planning permission. This is to ensure that each case is assessed individually on its own merits and for suitability and impact.
Many LPAs use Article 4 Directions to control the spread of HMOs or other sensitive uses. An Article 4 Direction removes permitted development rights, even for small HMOs (C3 to C4), ensuring stricter planning control.
Since Sui Generis uses are already outside the bounds of permitted development, Article 4 does not directly change their planning requirements. However, it reinforces the need for careful pre-application strategy and professional input.
Most councils outline policies on Sui Generis uses in their Local Plans, often under housing, community safety, or environmental sections. Understanding local priorities and potential objections is critical.
Addressing these in the design and supporting documents significantly increases your chances of success.
A property owner in Croydon sought to convert a 3-bed semi-detached home into a 9-bed HMO. Due to the number of occupants, the proposal fell under Sui Generis Planning.
Steps Taken:
Result:
Approved with minor design adjustments. The council appreciated the proactive engagement and comprehensive approach.
Sui Generis Planning Usage requires detailed knowledge of both national and local policy. Mistakes or omissions can lead to delays, refusals, or enforcement action.
Some developments combine Sui Generis uses with others (e.g., takeaway + residential units). This adds complexity, as each component is assessed separately.
Planning permission is only one part of the puzzle. Building regulations approval is required for structural changes, fire safety, energy performance, and more. Get in touch today with an architectural consultant at 4D Planning to discuss your Building Regulations requirements.
Key Focus Areas
No. Both are Sui Generis uses and require full planning permission for change of use.
No. A 7-bed HMO is Sui Generis and requires planning permission.
Yes, if the use has continued for over 10 years (or 4 years for residential), you may apply for one. Otherwise no, you will need planning permission.
Navigating the world of Sui Generis Planning can be complex, but understanding it is essential for anyone developing or changing the use of a property. Whether you're investing in a large HMO, planning to open a new bar, or converting a commercial unit, proper planning is crucial.
By leveraging professional expertise, thoroughly preparing your planning application, and engaging with your local authority early, you can maximise your chances of a successful outcome.
Sui Generis Planning Usage may be unique, but with the right approach, it can be a highly rewarding path for property developers, landlords, and entrepreneurs alike. Just to give you an example, in 2025 we successfully sourced planning permission and listed building consent for a music school in Twickenham (Richmond). The proposed use falls under Sui Generis, although it could also fall under F1(a).
4D Planning have many years of experience obtaining planning permission for a range of Sui Generis uses all over Greater London and other parts of the UK. Each project is unique and requires individual attention to detail to ensure a successful outcome. Contact us today for a free consultation.
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