Uttlesford District Council v Secretary of State for the Environment and Rowland White [1991] 2 PLR 76
The point in plain English: A detached outbuilding with its own bedroom, bathroom, small kitchen and front door does not automatically become a separate dwelling. Whether it remains part of the same residential planning unit is a question of fact and degree.
What the High Court decided
A detached garage had been partly converted to provide small living accommodation intended for an elderly relative. The council argued that the self-contained facilities meant the annex had become a separate planning unit.
The Inspector found that the house and annex remained one planning unit in single-family occupation. The High Court upheld that conclusion. The presence of facilities allowing a degree of independence did not, by itself, require the annex to be treated as a separate dwelling.
The court also emphasised that the correct first question was whether the proposal involved a material change of use. Only if it did would the separate statutory question of incidental use need to be addressed.
Why it matters for annexes
There is no single checklist turning an annex into a separate dwelling. Physical and functional relationships, occupation and the overall planning unit all matter.
See Planning Geek’s guide to planning units, ancillary and incidental uses.
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