Most sheds, workshops, and outbuildings don't need planning permission. But the rules are more nuanced than most people realise — and the size and siting conditions trip up a significant number of projects that suppliers and contractors wave through as clearly fine.
Usually no — within the Class E permitted development limits. The height rules and 50% coverage rule are where projects fall foul.
An outbuilding is permitted development under Class E of Part 1 of the GPDO if it is single storey, maximum eaves height does not exceed 2.5 metres, maximum overall height is 4 metres (dual-pitched roof) or 3 metres (any other roof type), reduces to 3 metres maximum if within 2 metres of any boundary, is not forward of the principal elevation, total outbuilding and extension coverage does not exceed 50% of the garden, is used for purposes incidental to the house, and the property is not listed or in a conservation area with highway visibility.
Flat-roofed and mono-pitch outbuildings are limited to 3 metres, not 4. The 4-metre limit applies only to dual-pitched roofs. Many off-the-shelf buildings are sold at heights that assume 4 metres applies to all roof types — it doesn\'t. Any outbuilding within 2 metres of any boundary (not just the rear boundary) drops to a 3-metre maximum regardless of roof type.
All outbuildings, extensions, and additions to the garden count together toward the 50% limit. A large workshop combined with existing garages and a rear extension can easily exceed 50% of the original garden area. The outbuilding must also be used for a purpose incidental to the house — a commercial operation run from an outbuilding may constitute a material change of use requiring planning permission.
Standard searches check the public register. We go further — querying live portals, blocked legacy systems, pre-merger authority databases, committee PDF archives, Land Registry title constraints, and comparable decisions across your postcode cluster. What we retrieve determines what you know before you build, buy, or appeal.