Class Q Permitted Development: Converting Agricultural Buildings to Homes

What is Class Q permitted development?

Class Q is a permitted development right that allows the change of use of an agricultural building, and certain associated building operations, to create one or more dwellinghouses. It was introduced to help bring redundant farm buildings back into productive use and to support rural housing without the need for a full planning application.

Although it is a permitted development right, Class Q is not automatic. You must apply to the local planning authority for prior approval, and the authority will assess your proposal against a defined set of criteria before you can proceed.

How many homes and how much floorspace does Class Q allow?

The limits on Class Q have changed over time, and the rules were significantly amended in 2024. In broad terms, an agricultural unit can deliver a set number of new homes up to a combined floorspace cap, with a limit on the size of any individual dwelling. Larger conversions and a greater number of units are now possible than under the original rules, but the floorspace and unit caps still apply and must be checked carefully for your specific holding.

Because the thresholds are detailed and have been revised, it is important to confirm the current limits before designing your scheme. Getting the number of units or the floorspace wrong is one of the most common reasons a Class Q application fails.

What does the council assess at prior approval?

When you apply for prior approval under Class Q, the local planning authority can only consider a defined list of matters. These include:

• Transport and highways impacts of the development
• Noise impacts of the development
• Contamination risks on the site
• Flooding risks on the site
• Whether the location or siting makes the dwelling impractical or undesirable
• The design and external appearance of the building
• Whether the building is structurally capable of conversion

Frequently asked questions

Does my building qualify for Class Q?
To qualify, the building must have been in lawful agricultural use on the relevant qualifying date, must be structurally capable of conversion without substantial rebuilding, and must not sit within an excluded area such as certain protected landscapes. Listed buildings and sites with an existing planning condition restricting change of use are also excluded. A site-specific assessment is the only reliable way to confirm eligibility.

How long does a Class Q application take?
The local planning authority has a statutory period of 56 days from the date of a valid application to determine whether prior approval is required and, if so, whether it is granted. Preparing a strong application with the right supporting information up front, including a structural assessment, gives you the best chance of a positive decision within that window.

What if my building is too dilapidated to convert?
Class Q only permits a conversion, not a rebuild. If the structure requires works that go beyond what the rules allow, the proposal can fall outside Class Q and be refused. Where a building is borderline, a structural engineer's report is essential, and in some cases a full planning application for replacement or new build may be a more realistic route. We can advise on the best strategy for your particular building.