A building or part of a building counts as a dwelling at any time when—
Land that is, or is at any time intended to be, occupied or enjoyed with a dwelling as a garden or grounds (including any building or structure on such land) is taken to be part of that dwelling at that time.
Land that subsists, or is at any time intended to subsist, for the benefit of a dwelling is taken to be part of the dwelling at that time.
A building, or part of a building, used for a purpose specified in section 116(2) or (3) of FA 2003 is not used as a dwelling for the purposes of subsection (1).
Where a building, or part of a building, is used for a purpose mentioned in subsection (4), no account is to be taken for the purposes of subsection (1) of its suitability for any other use.