A flat or home unit often includes areas (for example, a laundry, storeroom or garage) that are physically separate from the flat or home unit. As long as you use these areas primarily for private or domestic purposes in association with the flat or home unit for the whole period you own it, they are exempt on the same basis that the flat or home unit is exempt.
However, if you dispose of one of these structures separately from the flat or home unit, they are not exempt. If one of these structures is compulsorily acquired without your flat or home unit also being acquired, see Compulsory acquisitions of part of your main residence.