What is Class Q?
Class Q of the General Permitted Development Order (GPDO) allows for the conversion of agricultural buildings into homes, offering a simplified and expedient alternative to the traditional routes via the planning system. Class Q has become a particularly valuable mechanism across rural England where redundant barns and farm structures present prime opportunities for development.
At Salmon Planning + Architecture we have helped numerous clients navigate the complexities of the Class Q rules to unlock the residential potential of agricultural buildings – especially in Somerset, Devon, Cornwall and across the South-West.
Analysis of the 2025 Changes to Class Q
The new regulatory changes to Class Q that came into effect on 21 May 2025 create important opportunities.
To benefit from immediate Class Q concessions, the building must have formed part of an established agricultural unit since 24 July 2023 (previously the date was March 2013).
The main change is that the previous limit of five dwellings has now been increased to ten, with the permitted floor space increased from a theoretical maximum of 865 sqm to 1000 sqm. Set against this, the maximum size of any dwelling has been reduced to 150 sqm ie, a limit of 100 sqm per dwelling for ten dwellings.
Also introduced is a new relief for buildings in existence on or before 24 July 2023. These buildings can now be extended by up to 4 m on an existing hard surface to the rear of the building. This will present opportunities for the conversion of smaller buildings. Protuberances of up to 200 mm will also now be permitted to allow for bat boxes or roof lights, for example.
The other major new concession is that many more rural buildings that are not in use for agricultural purposes will now benefit from Class Q opportunities.
The new rules apply to the following situations:
- If a building existed before 24 July 2023 and at that time was part of an Established Agricultural Unit (EAU), the building will be eligible for Class Q. If the building was part of an EAU after this date, ten years must pass to benefit from Class Q.
- If the building existed on or before 24 July 2023 and was at that time part of an EAU but after this date ceased to be part of an EAU and no longer used for non-agricultural purposes, it will now also benefit from the new Class Q rules.
- If the same building continued to be an EAU but has been used for non-agricultural purposes, the regulations now permit the building to benefit from Class Q. This is a major concession for buildings previously denied Class Q and means, for example, that a building used for stabling horses, or for storage use or for a business, can now benefit from Class Q rights.
Class Q does not operate in National Landscapes, National Parks, Conservation Areas, nor does it apply to heritage protected buildings or for buildings that do not have an existing ‘suitable’ access.
Conclusion
The new regulations are overwhelmingly positive and will allow more buildings to be converted into dwellings.
Whilst the size limit remains a constraint, by pursuing a long-term strategy it is possible for Class Q buildings to be replaced by high-quality, new-build dwellings that are unfettered by size limits.
