Outbuilding Planning Permission

When does an outbuilding need planning permission in England, and when is it permitted development? Understand the national height and curtilage limits, the incidental-use rule, and how to check your property before you build.

Outbuildings — sheds, home offices, gyms and stores — are covered by their own national permitted development class in England, built around height limits, how much of the garden you cover, and the requirement that the building is incidental to the enjoyment of the house rather than separate living accommodation.

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When it may be permitted development

These are the common features that keep a project on the simpler route.

The outbuilding is single storey within the national height limits — lower if it sits within two metres of a boundary — and does not cover more than half the curtilage.
It is genuinely incidental to the house (office, gym, store) rather than self-contained living or sleeping accommodation.
It sits to the rear, not forward of the principal elevation, and the property retains its full permitted development rights.

When planning permission is more likely

These are the usual triggers that push a scheme beyond straightforward PD rights.

The building exceeds the national height limits, is two storey, or covers too much of the garden under the curtilage rule.
It will be used as a separate dwelling, an annexe with sleeping accommodation, or a holiday let — uses that are not incidental and need permission.
The property is listed, in a conservation area, or in an Article 4 area, where outbuilding rights are commonly restricted by the local authority.

What CanUBuild checks

Faster answers before you speak to an architect or builder

The tool is designed to answer the first question most homeowners have: is this worth pursuing, and what is most likely to block it?

CanUBuild checks your exact address against national datasets for conservation areas, listed status, Article 4 directions, flood risk and tree preservation orders.

The outbuilding workflow captures the deciding details: height, distance to boundary, footprint relative to the garden, intended use and position on the plot.

You see nearby decided applications so you can gauge how your local planning authority has treated similar garden buildings.

FAQ

Questions people ask before starting a project

Do I need planning permission for a garden outbuilding?

Often not, if it stays within the national permitted development height and curtilage limits and is incidental to the house. But designations, position, or any residential use can require a full planning application.

How tall can an outbuilding be without permission?

National permitted development sets maximum heights that are lower within two metres of a boundary. Beyond those limits, or for anything two storey, you will usually need planning permission.

Can I sleep or live in an outbuilding?

Permitted development requires the building to be incidental to the main house. Using it as self-contained living or sleeping accommodation, or as a separate dwelling, takes it outside permitted development and generally needs permission.

Does being in a conservation area affect an outbuilding?

Yes. Conservation area and Article 4 controls commonly restrict outbuildings, especially larger ones or those visible from the street, making permission more likely.

Next step

Check your property before paying for drawings

Search for the address, choose your project type, and get a planning feasibility answer based on permitted development rules, constraints, and local precedent data.

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