Do you need Permission to Convert a House into Flats?

As a landlord, looking to convert a house into flats can be a clever move to maximise the rental income but could also allow for a higher total sale price. It also allows for flexibility; you might later choose to sell one flat and retain the other(s).

The short answer to the question above is yes – to convert a single dwelling to flats, you will need full planning permission and building regulations approval. There are a few other consents you may also need where applicable, as detailed below.

Image above – design by Louise, interior designer from Merton, London. See more and shortlist them for your home project here. 

Is subdividing a house classed as Permitted Development?

Subdividing a house in to multiple units does not fall under permitted development and full planning permission will be required.

Listed Building Consent 

If the original building is listed, you will need listed building consent on top of the full planning permission. It’s worth noting that altering a listed building to affect its character without consent is a criminal offence.

Conservation Area Consent

If the house is in a conservation area, you may need conservation area consent if any demolition works are required as part of the development.

Building Regulations

Property conversions will required Building Control approval. As with planning permission, your architect is well placed to advise and help submit this application.

Space standards – what’s the minimum size a flat can be?

There are National Space Standards that provide details for minimum acceptable sizes for the Gross Internal Area related to the level of occupancy, as well as key dimensions for habitable rooms, storage requirements and floor to ceiling heights.

Full details are available from this resource, but some of the key requirements are as follows:

‘The minimum floor to ceiling height is 2.3m for at least 75% of the Gross Internal Area.’

The minimum size for a flat is 37 m2. This is for a one bed flat for one person. *The brackets below for a 1b1p is where the flat has a shower room instead of a bathroom.

Fire regulations

You may also need to consult the fire service regarding fire escape issues and/or appoint a fire engineer.

Party wall award

If you are doing work that affects the structure of a shared wall or floor with a neighbouring property, you will need a Party Wall Award. See our article here on whether you will need a party wall surveyor: https://designfor-me.com/advice-and-tips/do-i-need-a-party-wall-surveyor/

Converting a house to an HMO

If you decide to convert your house to a HMO (house in multiple occupation) instead or as part of dividing it, you will need a licence.