HMO Change of Use Applications: When Converting a Property Needs More Than a Licence

Converting an ordinary family home into a shared HMO is a common way London landlords increase rental yield — but the conversion itself can trigger a legal process entirely separate from the HMO licence application. Understanding when a change of use application is needed, on top of licensing, avoids a costly surprise partway through a project.

What "change of use" actually means

Under planning law, different uses of a building fall into different use classes. An ordinary dwelling is use class C3. A small HMO (broadly 3-6 unrelated occupants) is use class C4. Moving a property from C3 to C4 is a change of use, which planning law treats as a distinct event from the HMO licensing process run by a different part of the council.

Permitted development — usually, but not always automatic

In most of England, a C3-to-C4 conversion falls under permitted development rights, meaning no specific planning application is needed for that change of use alone. However, as covered in our planning permission article, a significant number of London boroughs have removed this right via an Article 4 Direction, meaning full planning permission is required for exactly the same conversion.

Larger HMOs always need planning permission

For HMOs with 7 or more occupants (a "sui generis" use), planning permission is required everywhere in London regardless of Article 4 status — there is no permitted development route for HMOs at this scale.

Building regulations may apply too

Beyond planning, physical conversion work — adding partition walls, converting rooms, installing additional bathrooms or kitchens — will often separately require Building Regulations approval, particularly around fire safety, means of escape, and sound insulation between converted rooms. This is a third, distinct approval process from both planning and licensing.

Sequencing matters

Because these are genuinely separate processes with separate application routes and timescales, sort out the planning position first if there's any doubt about Article 4 status in your borough, before committing to conversion works or a licence application timeline that assumes the change of use is unproblematic.

We focus on licensing — but we'll flag what else you need

Our service handles your HMO licence application specifically. As part of reviewing your property, we'll flag if your borough's Article 4 status or the scale of your conversion suggests a separate planning or building regulations process is needed, so you're not caught out mid-project.