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Do I need planning permission or building control approval to merge two flats into one?

Merging two flats into one, commonly known as amalgamation is likely to require planning permission as it will impact the local planning authorities housing supply. The council’s views on this will vary from council to council. It is recommended that you contact your local planning authority to understand their position.

If you do not need to apply for planning permission then you can apply for a lawful development certificate to prove that the change is lawful.

Building regulations will be required if there are physical works taking place as part of the amalgamation, this may include removing walls or changing electrics. Visit the relevant common projects on our site for more information.

Common Questions

Can I change my house into a shared house for students (HMO)?

In many cases, yes. Converting a single residential property (Class C3) into a small House in Multiple Occupation (HMO) for up to six occupants can often be done under permitted development rights, specifically under Class L. This means that planning permission isn’t usually required.

However, if your property is located in an area covered by an Article 4 Direction, permitted development rights are removed, and you would need to apply for full planning permission to change the use from C3 (dwellinghouse) to C4 (HMO).  

Read more information about use class changes on Planning Portal

Do I need planning permission to put up a shed?

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

Can I use an outbuilding as a home office?

Yes, in most cases you can use an outbuilding as a home office without needing planning permission. As long as the use remains incidental to the main dwelling it is still considered part of your domestic residential use.

Read more about outbuildings

Do I need planning permission to replace an existing bay window?

Replacing the window within a bay window is treated the same as any other window. Meaning that the replacement of windows which have a similar appearance to those previously used would not require an application for planning permission.

Repairs, maintenance and minor improvements will also not require an application.

If you live in a listed building or a designated area then different rules may apply.

For more details on replacing windows, visit our common projects section.

Do I need planning permission to add a garden office?

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

Browse our Outbuildings Mini Guide

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