From our experience different residential clients require extensions for different reasons due to land use restrictions and/or personal needs.
For instance, most of our previous residential clients required extensions to increase their existing ground floor to mainly accommodate amenity space such as a visitors' toilet, utility area, and cloakroom storage. While others require larger extensions to increase a kitchen, dining area and living rooms on the loft or first floor.
Wrap around single/double extensions
Some extensions fall under permitted development certicate route while others require planning permission approval through the local council. Nonetheless, all extensions require building regulation approval.