Class Q or Class R for a redundant farm building
Class Q and Class R both let a redundant agricultural building change use without a full application, but the allowed works, floorspace ceilings and prior approval matters differ sharply.
A redundant farm building can go two ways under Part 3 of Schedule 2 to the General Permitted Development Order 2015 without a full planning application. Class Q turns it into houses. Class R turns it into a flexible commercial use. They are not alternatives you choose on preference, because each has its own qualifying date, floorspace ceiling and list of prior approval matters, and a building that qualifies for one may fail the other outright.
The short answer: Class Q is the residential route with the tighter tests and the bigger uplift in value. Class R is the commercial route with lighter conditions and a narrower set of permitted uses. Part 3 has been amended repeatedly, most recently in May 2024, so check the consolidated text of the Order on legislation.gov.uk before relying on any figure.
What each class permits
Class Q allows the change of use of an agricultural building, and the land within its curtilage, to dwellinghouses in Class C3, together with the building operations reasonably necessary to convert it. Since the May 2024 amendments the ceiling is 10 dwellings with 1,000 m2 of floorspace in total, and no individual dwelling above 150 m2.
Class R allows the change of use of an agricultural or forestry building to a flexible commercial use, with the permitted destinations drawn from storage and distribution in Class B8, hotels in Class C1 and the broad commercial, business and service Class E. The floorspace ceiling was also raised in May 2024, to 1,000 m2.
| Class Q | Class R | |
|---|---|---|
| Resulting use | Dwellinghouses, Class C3 | Flexible use in Class B8, C1 or E |
| Floorspace ceiling | 1,000 m2 in total | 1,000 m2 in total |
| Unit limits | Up to 10 dwellings, each no more than 150 m2 | No unit limit |
| Building works allowed | Those reasonably necessary to convert | Works to the interior only |
| Prior approval threshold | Always required | Where floorspace exceeds 150 m2 |
The works point is the one that decides most cases. Class Q permits a defined, limited set of operations: replacement of windows, doors, roofs and exterior walls, the installation of services, and partial demolition where reasonably necessary. Class R does not permit building operations beyond internal works at all, so a barn needing a new roof cannot be brought into commercial use under Class R and then fixed.
Qualifying conditions on the building and the unit
Both classes require the building to have been in agricultural use, as part of an established agricultural unit, on a specified date. The May 2024 amendments moved that date, and getting it wrong is fatal rather than fixable, so confirm the current date in the consolidated Order and gather the evidence for it early.
Both classes are also unavailable on certain land. Conservation areas, National Parks, National Landscapes, the Broads and World Heritage Sites are excluded, as are sites of special scientific interest, safety hazard areas, military explosives storage areas, scheduled monuments and listed buildings. A barn attached to a listed farmhouse is normally caught by the listing, which rules out both routes and sends you to a full application with listed building consent.
And the building has to be capable of conversion. Permitted development does not extend to works amounting to rebuilding, so a structure held up by its ivy is not a candidate. The honest test is whether the existing building could take the loads imposed on it with the limited works the class allows, which is a question for a structural engineer rather than for optimism.
Prior approval matters under each class
Class Q prior approval covers transport and highways impacts, noise impacts, contamination risks, flooding risks, whether the location makes residential use impractical or undesirable, and the design or external appearance of the building. That last pair gives the authority real discretion, and refusals on location are common for buildings in the middle of a working farmyard or at the end of a long unmade track.
Class R prior approval is narrower. Where floorspace exceeds 150 m2, the authority considers transport and highways impacts, noise impacts, contamination risks and flooding risks. There is no design matter and no impracticality test, which is why Class R applications are refused less often.
Both determinations run to 56 days. Prepare the highways evidence properly, because access onto a rural road with poor visibility is the most frequently cited reason on either route, and the distinction between the documents that answer it is covered in the comparison of a travel plan and a transport statement.
Land excluded, and the interaction between the two classes
Class Q and Class R draw on the same pool of agricultural floorspace, and the Order limits how much of a holding can be converted. Floorspace already converted under one class counts against what remains available under the other, so a farm that has used Class R on a 600 m2 barn has reduced the headroom for a later Class Q scheme.
That interaction rewards planning the whole holding at once. Decide which buildings are better as houses and which are better as workshops or storage before using either right, because the sequencing cannot be undone.
There is also a trap in using Class R first as a stepping stone. A building whose lawful use has become Class E or B8 is no longer in agricultural use, so it can no longer qualify under Class Q. The ladder only goes one way.
Evidence of previous agricultural use
Authorities ask for proof, and a statutory declaration on its own rarely satisfies them. What works:
- Dated aerial photography and historic mapping showing the building in agricultural context
- Rural Payments Agency records, Basic Payment Scheme or equivalent scheme claims, and field parcel records
- Invoices and accounts for feed, fertiliser, veterinary services or contracting
- Agricultural tenancy or contract farming agreements
- Photographs of the interior showing agricultural fitting out, dated
Where the holding was sold recently, get the evidence from the previous owner before the trail goes cold. A buyer who completes and then tries to reconstruct a decade of agricultural activity usually cannot.
Choosing between them, and when neither works
Class Q suits a sound, well-proportioned building with its own access, away from the working yard, in a location where residential use is credible. Class R suits a building closer to the yard, where noise and movements make housing hard to defend, and where a commercial occupier wants space without the design scrutiny.
Neither works for a building on protected land, a building that needs rebuilding, or a conversion that wants rooflights in a traditional barn where the authority takes a firm design line under Class Q. In those cases a full application, supported by a Planning Statement and a design assessment, is the straighter road, and the authority's own policies on rural reuse often allow more than the Order does.
A note on space standards: the 150 m2 cap under Class Q is a maximum, not a minimum, and the national space standard may still be a relevant consideration for the units created, as discussed in the comparison of the nationally described space standard and local minimum sizes.
PlanScope can draft the supporting statements for either route, with the prior approval matters set out as separate sections and the evidence gaps flagged for you to fill, and you can browse the full set at all 66 report types. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
This is general guidance, not legal advice. A lawful development certificate is the only formal way to confirm that a conversion is lawful, so check the position with your local planning authority or a qualified professional before relying on it.
Frequently asked questions
Can I use Class R first and Class Q later on the same building?
No. Once the lawful use has become Class E, B8 or C1 under Class R, the building is no longer in agricultural use and cannot qualify under Class Q. Converted floorspace also counts against the allowance available on the holding, so using one right reduces what remains for the other.
Does Class R allow me to re-roof a barn?
No. Class R permits works to the interior of the building only, so structural repairs, a new roof or new external walls fall outside it. Class Q does allow a limited set of operations reasonably necessary for conversion, including roof and wall replacement, but not works amounting to rebuilding.
What stops a Class Q prior approval most often?
Two matters that Class R does not include. The first is whether the location makes residential use impractical or undesirable, which catches buildings inside working farmyards and at the end of long unmade tracks. The second is design and external appearance, where authorities take a firm line on fenestration in traditional agricultural buildings.
Is a barn attached to a listed farmhouse eligible?
Usually not. Listed buildings are excluded from both classes, and a barn within the curtilage of a listed building is often caught by the listing itself. The route in that case is a full planning application together with listed building consent, supported by a heritage assessment of the building's significance.
How long does prior approval take?
The determination period for prior approval under Part 3 is 56 days from a valid application. If the authority does not notify a decision within that period, the development may generally proceed, but the application must have been valid and complete, so missing information is the usual reason the clock never properly started.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.