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.

Planning permission is not required for internal changes such as changing a bathroom to an accessible wetroom, however, if you live in a listed building, you will have to apply for listed building consent for any significant works, whether internal or external.

Building regulations approval will likely be required for changes to a make a bathroom accessible, specifically when the change will impact the structure of the room, drainage and electrical systems. It is recommended to have work completed by a member of the competent person scheme.

For houses, replacing windows with double glazing usually doesn’t require planning permission, provided the style and appearance are similar to the original. However, if you live in a flat/maisonette, listed building, or a conservation area, planning permission or listed building consent may be required, especially if the changes affect the external appearance.

Read more about planning permission for windows and doors for houses

Read about planning permission for windows and doors for flats and maisonettes

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A single storey rear extension can fall under permitted development, meaning planning permission may not be required providing it meets certain criteria.  

In terms of height, the extension must:

• Be no taller than four metres at its highest point

• Have eaves no higher than the eaves of the original house

• Not exceed the height of the original dwelling  

Read about planning permission for extensions on Planning Portal

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Balconies, verandas and raised platforms will often require planning permission as they do not fall under permitted development rights.

An exception to this is Juliet balconies which do not have any external access or platform, allowing them to be classed as permitted development.

A raised platform of under 0.3 metres is also allowed without planning permission, this may be an area with slightly raised decking.

When applying for planning permission for a balcony it is important to consider your neighbours privacy and garden. The features and location of the property may have a significant impact. If the building is listed or in a conservation area, then this may have a bearing on any decisions.