Outbuildings under permitted development are class E of the householder classes: a building, enclosure, pool or container within the curtilage of a house for a purpose incidental to the enjoyment of the house, allowed without an application provided the total ground covered by everything other than the original house does not exceed half the curtilage, the building is single storey within a height limit that drops within a distance of a boundary, nothing goes forward of the principal elevation, and on designated land nothing goes to the side of the house. Permitted development for outbuildings is the right a garden office, a studio, a workshop or a garage scheme runs on, and what can I build in my garden without planning permission is answered by the room left under the half-curtilage limit after what already stands. Outbuilding planning permission is needed where the use is not incidental, a self-contained annexe to live in, a business, a bedroom, or where the limits are exceeded; this page sets out permitted development garden buildings as the developer reads them, and the envelope sheet on this site reads the outbuilding room from the curtilage you measured.
The half-curtilage rule, and what counts against it
The limit is on the total area of ground covered by buildings, enclosures, containers and pools other than the original house, which means extensions, sheds, greenhouses, a swimming pool and a shipping container all count, and the curtilage it is a share of excludes the ground the original house covers. The sheet takes the curtilage without the house and the outbuildings already standing and returns the room left; a plot with a large existing garage and a pool may have none, whatever the garden looks like.
Heights, the boundary and the incidental use
An outbuilding is single storey with a maximum eaves height, a maximum overall height that depends on the roof shape, and a lower overall limit within a distance of a boundary; no veranda, balcony or raised platform; not forward of the principal elevation; and on designated land not between a side elevation and the boundary. The use must be incidental to the enjoyment of the house, a home office, a gym, a store, a hobby room, and an outbuilding fitted out as a self-contained dwelling, let out or used for a business is not within the class however it was built.
The annexe question, and what the file keeps
A garden building for a relative that shares the house's facilities and is used as part of the household may be incidental; one with its own kitchen, bathroom and front door lived in separately is a new dwelling and needs an application, and the line is drawn by the authority at a certificate application rather than by the builder. Curtilo Pro keeps the outbuilding reading against the plot with the curtilage, the existing buildings and the use intended, so the room the offer was built on is what the file shows; the order and the technical guidance cited below state the figures.
Questions people ask about outbuildings
How big can an outbuilding be without planning permission?
As large as the room under the half-curtilage limit allows after everything already standing, within the height limits, single storey, not forward of the house, and for an incidental use. The sheet on this site reads the room from your curtilage; the order cited below states the heights.
Can I live in an outbuilding built under permitted development?
Not as a separate dwelling: the class covers incidental use only. Sleeping accommodation used as part of the household is usually incidental; a self-contained unit is a new dwelling needing an application. The authority's view at a certificate application settles it.
Do outbuildings count against the extension limits?
Yes, both share the half-curtilage limit for the total ground covered other than the original house. The sheet reads the outbuilding room after the extensions you plan.
Sources
- legislation.gov.uk, The Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2 Part 1: the householder classes, the extension depths and widths, the outbuilding and porch limits and what designated land removes
- GOV.UK, Permitted development rights for householders: technical guidance, the government's reading of Part 1 with diagrams of the original house, the rear and side limits and designated land
- GOV.UK planning practice guidance, When is permission required: development, permitted development rights, prior approval and article 4 directions