Not all planning applications involve building something new. Sometimes the biggest change is what a building is used for. Converting a shop into a flat. Turning a house into an HMO. Making an office into a restaurant. These are change of use applications — and they play by different rules than extensions.
They also get refused more often. Significantly more often.
What Is a Change of Use?
In planning terms, every building has a designated "use class." When you want to change what a building is used for — from one class to another — you may need planning permission. The current system groups uses into classes, and some switches between classes are allowed without a full application.
Class C3 — Dwelling houses (a single household living as a family)
Class C4 — Houses in multiple occupation (HMOs, 3–6 unrelated people sharing)
Sui Generis HMO — Larger HMOs (7+ people) — always needs permission
Class E — Commercial (shops, offices, restaurants, gyms, clinics — merged in 2020)
Class F.1 — Learning and non-residential institutions
Class F.2 — Local community uses
The 2020 merging of shops, offices, and restaurants into a single Class E was one of the biggest planning reforms in decades. You can now change between these uses without any planning application at all.
When You Don't Need Permission
Some changes of use are "permitted development" — meaning you can make the switch without a full planning application, though you may need "prior approval."
Class E to C3 (Class MA) — commercial to residential. Needs prior approval. The building must have been in commercial use for at least 2 years and vacant for at least 3 months.
Within Class E — shop to office, office to restaurant, etc. No application needed.
C3 to C4 — house to small HMO. Permitted development in most areas, BUT many councils have Article 4 directions removing this right.
Prior approval is not the same as planning permission. It's a lighter-touch process where the council can only assess specific impacts (noise, transport, flooding) rather than the full range of planning considerations. But it's not automatic — councils can and do refuse prior approval applications.
Why Change of Use Applications Get Refused More
Change of use applications — particularly conversions to residential — face higher refusal rates than standard householder extensions. There are structural reasons for this.
Impact on neighbours is different. An extension affects one or two adjacent properties. A change of use — especially to an HMO or to multiple flats — can affect an entire street. More car parking, more bins, more noise, different hours of activity. Planning officers weigh these impacts heavily.
Amenity standards are hard to meet. Converting a commercial building into flats requires adequate light, ventilation, outdoor space, and room sizes. Many commercial buildings simply can't meet residential standards without significant compromise.
Loss of commercial use. Councils in many areas are trying to protect high streets and employment land. Converting a viable shop or office to residential use may conflict with local plan policies about maintaining commercial activity.
HMO concentration. Many councils have policies limiting the proportion of HMOs on a street. If your street already has several, another conversion is likely to be refused regardless of the quality of your application.
Check approval patterns in your area →
Flat Conversions: The Numbers
Converting a house into flats is one of the most commonly refused application types in our dataset. The reasons are consistent: insufficient parking, inadequate bin storage, loss of family housing, and impact on the character of the area.
Councils in areas with high housing demand — particularly London boroughs — are especially resistant to losing family-sized homes to flat conversions. Many have explicit policies requiring replacement family units or minimum size thresholds below which conversion isn't permitted.
The approval rate varies enormously by council. Some approve the majority of flat conversions. Others refuse more than they approve. Your council's local plan policy on conversions is the single most important factor.
HMOs: The Most Contested Change of Use
HMO applications are politically charged. They provoke strong reactions from neighbours, they concentrate demand for parking and waste collection, and they change the character of residential streets. Many councils have responded by introducing Article 4 directions that remove permitted development rights for C3 to C4 conversions — meaning you need planning permission even for a small HMO.
If your council has an Article 4 direction covering HMOs, you'll need full planning permission to convert a house to a small HMO — even though this would normally be permitted development. Check with your council before assuming you can convert without applying.
In areas with Article 4 directions and HMO concentration policies, refusal rates for HMO applications can exceed 40%. In areas without these restrictions, the approval rate is much more favourable.
How to Improve Your Chances
- Check the local plan first. If your council has policies protecting the existing use (e.g. protecting family housing or high street retail), a change of use application is starting from a weaker position.
- Address parking and bins. These are the most common practical objections. Show how you'll provide adequate parking and waste storage in your application.
- Meet residential standards. If converting to dwellings, ensure every unit has adequate natural light, ventilation, minimum floor areas, and some form of outdoor amenity space.
- Check precedent. Has a similar change of use been approved nearby? That's your strongest evidence that the principle is acceptable in your area.
What gets approved in your area?
PlanningLens analyses real planning decisions near your postcode — including change of use applications. See what your council approves and refuses.
Check Your Postcode — Free →The Bottom Line
Change of use applications face more scrutiny than extensions. The refusal rates are higher, the policy landscape is more complex, and the political sensitivity — especially around HMOs and loss of commercial space — adds an unpredictable element.
But "riskier" doesn't mean "impossible." The majority of change of use applications are still approved. The key is understanding your council's specific policies, addressing the common refusal reasons upfront, and checking what's been approved nearby before you invest in a full application.
Free Postcode Check
See approval rates, comparable decisions, and refusal patterns near your property. Data from 2,500,000+ real planning decisions.
Check Your Postcode →