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Barn conversions guide: planning permission and costs

A complete guide to barn conversions in the UK, covering: planning, building regulations, and budget.

4 min read

Is there any project more quiescently British than a barn conversion? With their high ceilings, rustic beams, and general country-ness, who wouldn’t want to spend their days in one?

So if you’re thinking of purchasing your own barn or putting to good use that old outbuilding round back, here’s everything you’ll need to know about this conversion classic…

Planning permission

Changes to planning laws in 2014 mean you can convert a barn under permitted development rights. This government scheme allows certain projects to go through without the need for full planning permission, and in the case of a barn conversion, can be utilised to create up to five new residential dwellings.

However, like with many planning laws, the rules around permitted development can be a little complex. Barn conversions fall under a Class known as ‘MB’, found in Part 3 of the Second Schedule of the General Permitted Development Order.

You’re able to convert your barn into a dwelling if the following conditions are met…

  • The site must have only been used for agricultural use.
  • The barn in question must have been standing by 20th March 2013. If you wish to convert a new barn, it’ll need to have existed solely as an agricultural building for at least 10 years.
  • The total floorspace of your barn to be converted must be no more than 465m².
  • The 465m² can be divided into five separate dwellings.
  • If the site is subject to an agricultural tenancy, landowners must have the express consent of their tenants.

It’s also worth noting that under this Class, permitted development allows reasonable construction operations, but only within the existing structure. New internal walls? Fine. New doors and windows? You’re good to go. But if you want to simply knock down flimsy elements and essentially build a residence from scratch, then this won’t be covered.

What's more, you’re barn conversion will also be excluded from the scheme should you reside in a conservation area or national park.

Lawful Development Certificate

Think you’re out of the planning woods? Think again.

While you might not need a full planning application, you will need to obtain a lawful development certificate. This is vital for a barn conversion, and failure to do so could result in heavy fines or even the demolition of your project.

To prove your build is legal, you’ll need to give Prior Notification to your local authority. This will involve submitting your proposed designs and having them reviewed in order to make sure you’re within your permitted development rights.

Other considerations will be…

  • Transport
  • Noise impact
  • Contamination
  • Flood risk
  • And ‘whether the location or siting of the building makes it otherwise impractical or undesirable for the building to change from agricultural use to residential use.’

Including the wait for your project to be validated and assigned a planning officer, this stage can take anywhere between 8-13 weeks. To give yourself the best chance of first-time approval, we recommend getting an architect to handle the process on your behalf.

Building regulations

Building regulations are a set of statutory requirements that all buildings must meet in order to create a safe and healthy environment to inhabit.

They cover everything from the structure, thermal performance, sound-proofing, drainage, all the way to fire safety - to name just a few!

To ensure your project is in line with UK building regulations, you must commission a set of technical drawings of your proposed build, demonstrating all legal requirements have been met, before submitting this to either your local building control or by hiring a private approved inspector.

The scope of work covered by this stage means you’ll need more than one professional on board to prepare your application. For a barn conversion, this will typically include…

  • A structural engineer
  • An architect
  • A CCTV surveyor
  • A party wall surveyor
  • An approved inspector

Learn more about building regulations.


Your budget will depend on a lot of different factors, such as…

  • State of the existing structure
  • Complexity of design
  • Project size
  • Professionals hired
  • Location of your project
  • Quality of materials

For smaller barns, you’ll likely need a budget of £80 - 100,000. For large scale projects, this could go up to £250,000.

Learn more about your finance options.

Looking to create a barn conversion of your own? Resi offers free consultations, giving you expert advice on everything from budget, timelines, to design. Book yours today - did we mention they’re free?

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