Some of the best development opportunities aren't new sites at all. They're buildings already standing, already serviced, already connected to the grid, just sitting in the wrong use. Think an empty high street unit with flats written all over it, a redundant barn a stone's throw from the nearest village, an office block nobody's booked a desk in since 2021.
The question that decides whether any of that potential is worth pursuing is deceptively simple: do you need full planning permission for the change of use, or is there a faster route in? Get that answer right early, and you save yourself months of guesswork, or a very expensive enforcement notice.
This guide walks through what counts as a change of use, the two routes into one, what building regulations expect of you, and - because knowing the rules is only half the job - how to actually find these opportunities before someone else does.
In planning terms, a change of use happens when a building or piece of land is used for something materially different from what it was last authorised for. That might mean turning a shop into a restaurant, an office into flats, or a redundant agricultural building into a home.
The framework for all of this is the Use Classes Order, substantially reshaped in 2020. The changes bundled most shops, offices, gyms, nurseries and light industrial units into a single, flexible Class E, separated out the community and leisure uses that used to sit alongside them into Class F, kept residential uses under Class C, and left everything that doesn't fit neatly anywhere - takeaways, pubs, drive-thrus, theatres - as sui generis, meaning "its own kind" in planning terms. We've covered Class E and its permitted development implications, along with the wider use classes system, in more detail elsewhere, so we'll keep things at a summary level here.
Here's the bit that trips people up: not every change of use needs permission. Moving between uses within the same class - say, from a hairdresser's to an estate agent's, both Class E - generally needs nothing at all. It's only when a change is "material" that planning steps in, and material simply means the change is significant enough to affect how the site is used, how it looks, or what impact it has on the people around it.
Once you've established that a change of use is material, there are two ways to get there: permitted development or full planning permission. Which one applies depends almost entirely on what you're converting from and to.
Route one: permitted development. The General Permitted Development Order grants automatic rights for specific, pre-approved conversions, provided you meet the criteria and, in most cases, secure prior approval from the local authority. Class MA covers the move from Class E commercial space to residential, and has become the default route for high street and office conversions since it replaced the old Class O and Class M rights. Class Q allows agricultural buildings to become homes, subject to its own set of size and design conditions. Class G, alongside a handful of other classes, covers further specific conversions worth knowing about if they apply to your site. Each of these has enough nuance to warrant its own guide, so we've gone into the detail separately - this page is about knowing which door to knock on, not replicating what's behind it.
Route two: full planning permission. If your conversion doesn't fit a permitted development class, you're into a full application. This typically covers sui generis moves (turning a shop into a hot food takeaway, for example), most changes into commercial or industrial use, and anything within an Article 4 direction area, where a local authority has deliberately removed PD rights to protect the character of a high street, conservation area or similar.
As a rough decision flow: if you're staying within the same use class, you likely need nothing. If you're moving between classes and a PD right exists for that specific move, you're looking at prior approval. If neither applies, or you're in an Article 4 area, it's a full planning consent change of use application. For the full picture on permitted development rights generally, including size and design limits, our permitted development guide is the place to go deeper.
If you land on the full application route, a bit of groundwork before you submit will save you time later. Pre-application advice from the local planning authority is worth having, even where it's not compulsory - it flags concerns early, before you've committed a full set of drawings to them.
A typical application needs scaled plans of the existing and proposed layout, a planning statement setting out the case for the change, and, depending on the site, supporting surveys covering things like parking, noise, contamination or ecology. What's proportionate varies enormously by site and use, so this is another area where pre-application conversations pay off.
Case officers weigh a change of use application against the local plan, checking it against policies on things like town centre vitality, housing mix and employment land protection. Beyond policy fit, they're looking at amenity impact on neighbours, highways implications (particularly for anything generating more trips or deliveries), and noise, especially where a quiet use is becoming a noisier one.
On timescales, minor applications are typically determined within eight weeks, with larger or more contentious schemes running longer. Fees vary by application type and floorspace, and both fees and timescales are covered in more depth in our planning permission guide and our guide to planning permission costs.
Here's a distinction that catches out a lot of first-time developers: planning permission and building regulations approval are entirely separate consents, and you can need one without the other. Get planning sign-off for your change of use and assume you're done, and you might find building control knocking on your door regardless.
The rule of thumb is that a material change of use - converting a shop to a flat, say, or a barn to a home - usually triggers a building regulations requirement, even in cases where the planning system itself doesn't ask for anything (because the change sits within permitted development, or falls under a class where no planning application was needed at all). Building regs exist to make sure the building is actually safe and fit for its new purpose, which is a different test entirely from whether the local authority is happy with the principle of the change.
In practice, that usually means addressing fire safety (escape routes, compartmentation, fire doors), sound insulation between units, particularly in conversions creating multiple dwellings, ventilation, and thermal performance, bringing insulation up to a standard appropriate for the new use. None of this is optional extra polish; it's what turns a converted shell into somewhere someone can legally live or work.
Everything above answers the "how do I get permission" question. The harder question, and the one that actually makes or breaks a pipeline, is "how do I find the right building in the first place?"
A good change of use opportunity tends to have a recognisable shape: underused Class E stock on a high street with better value as residential, vacant space above shops that's been empty for years while the ground floor trades on, or redundant agricultural buildings a Class Q conversion could turn into homes. None of these announce themselves. They sit quietly in plain sight until someone with the right search does the legwork.
That's where a lot of developers spend more time than they'd like - driving streets, checking Rightmove, chasing agents for tips. The more systematic approach is to search by use class, vacancy signals and planning history across a wider area, then narrow down to the sites where a conversion genuinely stacks up.
This is the gap LandInsight is built to close. You can filter sites by use class to surface Class E, agricultural and other conversion candidates directly, pull up comparable conversions nearby to sense-check whether a scheme's viable, and check the planning history on any given building, including previous applications, refusals and approvals, before you've spent a single hour on due diligence. Instead of hoping you stumble across the right opportunity, you can go looking for it deliberately.
Find conversion opportunities by use class with LandInsight.
Do I need planning permission to change the use of a building?
It depends on the move. Staying within the same use class usually needs nothing. Moving between classes might qualify for permitted development, or might need a full planning consent change of use application, depending on the specific classes involved and whether an Article 4 direction applies.
What is a material change of use?
A change significant enough to affect how a site functions, how it appears, or what impact it has on the surrounding area. Minor internal changes within the same use class generally don't meet this bar; moving between distinct uses usually does.
Can I convert an office to residential without planning permission?
Often, yes, via Class MA permitted development rights, though prior approval from the local authority is still required and the conversion needs to meet specific conditions. Our Class MA guide covers the criteria in full.
Do I need building regulations approval for a change of use?
In most cases, yes. A material change of use typically triggers building regs requirements around fire safety, sound insulation, ventilation and thermal performance, regardless of whether planning permission was needed for the change itself.
How long does change of use permission take?
For permitted development, prior approval decisions are typically made within a matter of weeks. Full planning applications for minor changes are usually determined within eight weeks, with larger schemes taking longer.
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