Yes, but this type of conversion will require full planning permission. This is because you’d be changing the use of the ground floor from residential to commercial (typically to a use class such as E), while the upper floor would remain as a residential flat (Class C3). The change of use triggers the need for planning approval.  

Find out more about change of use

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Rules governing outbuildings apply to sheds, playhouses, greenhouses and garages as well as other ancillary garden buildings such as swimming pools, ponds, sauna cabins, kennels, enclosures (including tennis courts) and many other kinds of structures for a purpose incidental to the enjoyment of the dwellinghouse.

If you are unsure if your planned building falls into the category of 'outbuildings' or if you are unsure if planning permission is required, please contact your local planning authority.

Outbuildings are considered to be permitted development, not needing planning permission, subject certain limits and conditions.

Read about the limits and conditions for outbuildings

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If you carry out development without the necessary planning permission, and it doesn’t fall within permitted development rights, you may be in breach of the planning rules. In such cases, you will usually need to submit a retrospective planning application to seek approval for the work already completed or started. However, there is no guarantee that permission will be granted.  

Learn more about planning breaches on Planning Portal  

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Once submitted, your planning application first goes through a validation process. After its validated, the formal decision period is 8 weeks. However, in some cases, especially for more complex proposals or if further information is needed, your local authority may request an extension of time.

Understand more about the decision-making process on Planning Portal

You may wish to make loft alterations to enhance the storage facilities available or to increase the living space of the home. Converting the loft of a house is considered to be permitted development (not requiring an application for planning permission) subject to certain limits and conditions.

Remember, building regulations approval is required to convert a loft or attic into a liveable space.

Find out about loft conversions

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There are different rules for flats and maisonettes regarding loft conversions. Read guidance for converting the loft of a top floor flat.

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