Ancillary area
An ancillary area of a building is an area that supports the function/s of the primary areas, that is, it is not part of the primary purpose of the building, but is required in order that the primary purpose can function.
Examples of ancillary areas include:
- Plant rooms.
- Cleaners’ rooms.
- ICT rooms.
- Building services rooms.
- Storage rooms.
- Circulation spaces.
In shared buildings, an ancillary area might support more than one occupant, e.g. a shared kitchen, meeting spaces, utility areas, and so on.
In residential buildings, ancillary areas include spaces which do not form part of the main dwelling directly, but nonetheless add some useful value, e.g. patio area, office, garage, conservatory, porch, utility room, and so on.
NB Planning Gateway One – Glossary, published on the Planning Portal, defines ancillary accommodation as: ‘Rooms or spaces in a building used to support the residential use, such as refuse stores, cycle stores, plant rooms and storerooms.’
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