There are three different types of extensions.
- Single storey extension
- Two storey, or multi-storey extension
- Over-structure extension (typically over-garage)
Single storey extensions are built on to a part of the house whereby one side (or more) of the extension adjoins the property. Single storey extensions are only the ground floor, plus any basement built to it.The main consideration with these extensions are the size, impact on neighbours, and the roof.
Two storey, or multi-storey extensions, can be built to any part of the existing building as with a single storey extension. There is however a much stronger possibility of nuisance towards neighbours, so even if planning permission is not required, it’s advised to get a letter from the Planning Department.
Over-structure extensions are when you are extending over the top of an existing structure such as a garage, kitchen, living or dining room. This is not always simple. The existing structure may not be strong enough to support such an extension, and so sometimes a new foundation or other extra structural support may need to be installed. Planning permission is not always required, but Building Control certainly is.