You might have come across the term “Class Q Permitted Development.” This piece of planning legislation allows certain barns to be converted into residential dwellings without needing full planning permission.
Yet, not all barns qualify. Misunderstanding the criteria could lead to costly delays.
As a barn conversion architect, I’ll break down what you need to know before you begin.
Class Q is a permitted development right under the Town and Country Planning (General Permitted Development) (England) Order 2015.
In simple terms, it allows the conversion of certain agricultural buildings into homes – without going through the full planning permission process.
It’s especially useful for landowners or buyers who want to convert an unused barn into a family home, holiday let, or even multiple dwellings, but don’t want to go through months of formal planning.
Not every barn is eligible. To qualify under Class Q, your building must meet strict conditions:
The barn must have been part of an established agricultural unit on or before 24th July 2023.
It must be structurally capable of conversion.
This doesn’t allow complete rebuilds. The barn must be strong enough to support the new structure : walls, roof, etc. without major works. You will usually require a structural report as part of your application to prove this.
It must be in England and not in a restricted location, such as:
National Parks
Areas of Outstanding Natural Beauty (AONB)
Conservation areas
Sites of Special Scientific Interest (SSSI)
Listed building
Under current Class Q rules, you can convert:
Up to 10 dwellings per agricultural unit
A maximum of 1000 square metres of floor space
This could be:
3 x large family homes
5 x smaller homes (under 100 sqm each)
Or a mix of both
Although Class Q skips full planning permission, you still need to apply for Prior Approval from your local authority.
They will assess:
Transport & access.
Flood risk
Noise/environmental impact
Design and external appearance
Natural light in habitable rooms
Important: If the barn is in poor condition, not structurally sound, or previously used for something other than agriculture, the council can reject the application.
When planning a barn conversion, many clients ask:
“Should I apply for planning permission or use Class Q?”
The answer depends on the type of barn, your design goals, and the location of the site. Here’s a quick breakdown:
Feature | Class Q (Permitted Development) | Full Planning Permission |
Eligibility | Agricultural buildings only | Any structure (incl. listed barns) |
Design Flexibility | Limited. You must retain much of the original structure | Full flexibility (subject to local planning) |
Speed | Faster — Prior Approval usually takes 8 weeks | Slower. Planning may take 12+ weeks |
Risk | Risk of rejection if structure isn’t sound or doesn’t qualify. | More subjective, but wider design scope. |
Location Limits | Not allowed in AONB, National Parks, etc. | Can apply anywhere (with justification) |
Cost | Lower upfront costs | Higher costs for drawings and reports |
Time Limits | Must be completed within 3 years | Must be substantially started within 3 years |
You want to convert quickly
The barn is structurally sound
You’re satisfied with a modest design
The site isn’t listed or protected
The barn is listed, or in a conservation area
You want to extend, alter, or modernise the structure significantly
You have design ambitions that Class Q won’t allow
Pro Tip: Start with a Class Q assessment. If it is not viable, a well-prepared full planning application is often the better route
Pros:
Faster approval process (typically 8 weeks)
No formal planning permission required
Can increase land value significantly
Cons:
Not applicable to listed buildings or sensitive sites
Limited design flexibility. Major alterations may invalidate your rights
Structural limitations can increase build costs
As a specialist barn conversion architect, I can:
Assess Class Q eligibility before purchase
Work with structural engineers to confirm viability
Design a compliant layout that maximises light, flow, and usability
Prepare and submit Prior Approval applications
If Class Q fails, pivot to a full planning application with a robust case
Class Q can be a powerful route to barn conversion, but only when the conditions are right. Many of our clients start with Class Q in mind, only to find full planning is a better long-term solution for their site and design aspirations.
Either way, the key is understanding your options early. If you’re considering a barn conversion, I’d be happy to help assess the best path forward.
Get a step-by-step overview of planning, design, and construction from a specialist barn architect or view our barn conversion services
Let’s explore the potential of your barn project.
Get in touch, David would be happy to guide you through the process.