Installing patio doors at the rear of your house is likely to fall under permitted development rights, meaning an application for planning permission is not required, provided certain limits and conditions are met.

The doors should be of similar appearance to those previously used, if they are not then generally planning permission will be required.

If you live in a listed building, you will need listed building consent for any significant works.

If you live in a designated area such as a conservation area or national park, then additional restrictions may be in place.

If you are unsure whether the work falls within permitted development rights you can check with your local planning authority or submit a lawful development certificate to prove the change is lawful and prevent any future enforcement action.

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Following a grant of planning permission, it may be necessary to make amendments to the proposals that were originally approved. A non-material amendment may be applied for to approve a minor change to the planning permission which does not breach any conditions originally placed on the consent.

There is no statutory definition for ‘non-material’ as it can vary on a case-by-case basis. In general, if the change will increase the size, change the appearance of a development or have a large impact on other considerations then it will not be considered non-material.

Read more about this non-material amendment applications.

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Planning permission is not normally required to turn two properties into one by knocking through a party wall provided the changes are internal and do not impact the external appearance of the property.

You should check with your local planning authority that they agree, and there are not any previous planning changes or conditions which may have an impact.

Additional permissions may be required depending on the building’s history and their location. If the building is listed, an application for listed building consent will be required before any major changes are made to the dwellings.

The work will have to comply with building regulations, the focus will be on structural work and safety.

‍Read more about how building regulations apply to internal walls.

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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There is no single legal definition of "habitable room", as its use and meaning are subject to context. Generally, a habitable room is a space in a building that is designed for people to live, sleep, or spend extended periods of time in, but does not include bath or toilet facilities, corridors or utility rooms.