HMO planning permission in London: Class C3, C4 and sui generis

The use classes explained

Class C3 is an ordinary residential house or flat lived in by a family or a single household.

Class C4 is a small HMO: shared by 3 to 6 unrelated people who share facilities such as a kitchen or bathroom.

An HMO for more than 6 people is 'sui generis', meaning it sits in a class of its own and always needs a full planning application.

C3 to C4 and Article 4 directions

A change from Class C3 to a small Class C4 HMO is normally permitted development. Many London boroughs have Article 4 directions that remove this right in parts or all of the borough, so planning permission is then required.

Always check whether an Article 4 direction covers the address before buying or converting.

Planning is separate from licensing

HMO licensing is a separate process run by the council's housing team. Planning permission does not grant a licence, and a licence does not grant planning permission.

What councils look at

Councils typically consider room sizes, shared kitchen and bathroom space, waste and cycle storage, the effect on neighbours, and how many HMOs already exist nearby. Clear, accurate floor plans are essential.