Garden room in Hammersmith and Fulham

Often not, for houses with a rear garden — Class E permitted development allows an incidental-use outbuilding (office, gym, studio) under 2.5m high within 2m of a boundary, covering no more than half the garden, with no sleeping accommodation. That rear placement can still qualify in many conservation areas; listed curtilage and flats are the main exceptions. Side placement in a conservation area, or any self-contained sleeping use, needs a full application.

Rear-garden rooms proceed under PD on many houses; listed curtilage and flats are the exceptions.

Garden rooms proceed under permitted development on many houses here, especially where the rear garden is deep enough to clear the 50% coverage rule without squeezing the boundary-height limit. Listed curtilage removes Class E entirely, and flats never had outbuilding rights in the first place — both are common enough in parts of the borough that tenure and listing are worth checking before ordering a pod. A Lawful Development Certificate is cheap insurance when you sell.

Permitted development (GPDO Class E) allows outbuildings for purposes incidental to the house: maximum 2.5m height within 2m of a boundary (4m for dual-pitched roofs further in), no more than half the garden covered, nothing forward of the principal elevation, and no sleeping accommodation. Within conservation areas Class E still applies at the rear, but outbuildings at the side are excluded.

The 'incidental use' test matters: an office or gym qualifies; a self-contained annexe or rentable unit does not and needs full permission. Listed buildings lose Class E entirely — any outbuilding in the curtilage of a listed house needs an application. Where you intend to run a business with visitors or convert to sleeping space later, take the planning route up front.