Evidence pack checklist for a Class Q barn conversion

Class Q prior approval turns on two things you have to prove before anyone looks at the design: that the building was in agricultural use on the qualifying date, and that it is structurally capable of taking the conversion without being rebuilt. Applications fail on those two points far more often than on highways or flooding. Everything else in the pack supports them.

Class Q sits in Part 3 of Schedule 2 to the General Permitted Development Order 2015 and permits change of use of an agricultural building to dwellinghouses, with limited associated building operations.

Establishing agricultural use on the qualifying date

The class requires the building to have been used solely for an agricultural use as part of an established agricultural unit on a specified qualifying date, or, for buildings first used later, for a stated period before the application.

The evidence is documentary and it should be indexed:

• Farm business records, subsidy or grant scheme correspondence showing the holding and its buildings
• Livestock movement records, feed and fertiliser invoices addressed to the holding
• Agricultural tenancy agreements, with the dates and the land they cover
• Dated aerial or satellite imagery showing the building in agricultural context
• Historic ordnance survey extracts and any earlier planning history
• Photographs of the building in agricultural use, dated where possible
• A statutory declaration from the owner or a former occupier where the record has gaps

Use of the word solely matters. A building that has been part let for storage of caravans or used by a non-agricultural business will fail the test, and authorities do check against business rates and enforcement records.

The class also carries conditions about agricultural tenancies. Where the building is subject to a tenancy, the application has to address the tenant's position, so establish that before spending on surveys.

Structural evidence and what it must show

The permitted building operations are limited to those reasonably necessary to convert the building: installation or replacement of windows, doors, roofs and exterior walls, the services needed for a dwelling, and partial demolition to the extent reasonably necessary.

So the structural report has to answer a specific question. Not whether the building can be made habitable, but whether the existing structure is capable of taking the conversion using works within those limits. Where the frame would need substantial replacement, or where new foundations and a new structural frame would effectively produce a new building, the works go beyond the class.

A useful report identifies the primary structure, assesses its condition member by member, states what has to be repaired or replaced and why, and concludes explicitly on whether the works fall within conversion rather than rebuilding. A Structural Survey written for a mortgage valuation does not do this, and submitting one invites a refusal.

Include existing photographs of the frame, the foundations where visible, and any deflection or decay, keyed to a plan.

Extent of works and external appearance

Design is a matter the authority may consider, and the limits on works shape what is possible.

Keep the existing openings where you can and justify new ones. Cladding and roof replacement are permitted where reasonably necessary, but a scheme that changes the roof pitch, raises the ridge or extends the footprint beyond what the class allows is outside the right. The class was amended in 2024, including the number of dwellings permitted, the floorspace limits for each and in total, and a limited allowance for a single storey extension onto existing hard surfacing. Read the current text of the Order, because checklists written before that change describe different limits.

The design case is stronger where the conversion reads as a converted agricultural building rather than a house in a field. That is not a policy test under the class, but it influences how the appearance matter is decided, and the same reasoning applies in a full application. A design and access statement for a barn conversion covers that ground for the alternative route.

Location, highways and the prior approval matters

The authority may consider transport and highways impacts, noise, contamination, flooding, the design and external appearance of the building, adequate natural light in habitable rooms, and whether the location makes it otherwise impractical or undesirable for the building to change to residential use.

That last matter is the one applicants underestimate. A building with no made access, remote from any settlement and reached by a track shared with a working farmyard can be found impractical, and the answer is evidence rather than argument.

Asbestos is worth calling out. Cement sheet roofing is common on agricultural buildings, and its removal is a management matter rather than a planning one, but a contamination desk study that ignores it reads as incomplete.

Reports commonly needed alongside

Ecology is the most common addition. Agricultural buildings support bats and barn owls, and a preliminary roost assessment with follow-up surveys in season is frequently required. Commission it early, because the survey season governs the programme more than the council does.

A Preliminary Ecological Appraisal is the usual starting point, and where roosts are found a licence will be needed before works begin.

Ordering the submission

1. Designation checks: the class is not available on certain designated land or for listed buildings, so confirm this first with dated map extracts.
2. Agricultural use evidence, indexed and paginated, with a covering schedule.
3. Structural report concluding on whether the works fall within conversion.
4. Existing and proposed plans and elevations, with floor areas annotated.
5. Technical reports matched to each prior approval matter.
6. Ecology survey results, or a programme showing when they will be available.
7. A short covering statement walking the officer through the qualifying conditions, then the prior approval matters, in order.

The determination period is 56 days, and development permitted by the class has to be completed within the period the Order sets, running from the date of prior approval. Diary that date on the day the approval arrives.

Where the building fails the structural test, a full planning application in the countryside is a very different proposition and should be approached as one, not as a reworked Class Q. Enter your postcode on PlanScope to see which reports a conversion of this kind is likely to need.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it, and note that a Lawful Development Certificate is the only formal way to confirm that works or a use are lawful. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.