Do You Need Planning Permission for an Outbuilding?

What counts as an outbuilding?

An outbuilding is any separate structure built within the land (known in planning as the curtilage) surrounding your home. The Planning Portal, a joint venture with the Ministry of Housing, Communities and Local Government, confirms that the rules covering outbuildings apply to sheds, greenhouses, and garages as well as other ancillary garden buildings such as swimming pools, ponds, sauna cabins, kennels, enclosures (including tennis courts), and many other kinds of structure for a purpose incidental to the enjoyment of the dwellinghouse. In practice this covers the most popular projects homeowners ask about: garden offices, home gyms, summerhouses, garden rooms, detached garages, and outdoor pools.

What is permitted development and why does it matter?

Permitted development (often shortened to PD) is a set of pre-approved rights that lets you carry out certain building work without making a formal planning application. For outbuildings, these rights are set out in Class E of Part 1 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015 (as amended). The Ministry of Housing, Communities and Local Government has published separate technical guidance to help homeowners understand how the rules work in practice. If your outbuilding meets every condition in Class E, you can build it without applying to your local planning authority (your LPA, usually your district or borough council). If it does not meet every condition, you will need to apply for planning permission.

The six core permitted development conditions for outbuildings in England

The Planning Portal sets out the conditions that must all be satisfied for an outbuilding to be permitted development. Think of these as a checklist: failing any single point means the outbuilding falls outside the permitted development rules and will need full planning permission.

• No part of the outbuilding can sit forward of the wall that forms the principal elevation (the main front face) of the original house.
• The outbuilding must be single storey only.
• The eaves height (the point where the roof meets the walls) must not exceed 2.5 metres.
• The maximum overall height must not exceed 4 metres for a dual pitched roof, or 3 metres for any other roof type.
• If any part of the outbuilding is within 2 metres of the property boundary, the whole structure must not exceed 2.5 metres in height.
• No verandas, balconies or raised platforms are permitted. Any platform such as decking must not exceed 0.3 metres in height.
• The outbuilding must not be used as self-contained living accommodation and must not have a microwave antenna.

Height restrictions explained

The height rules are the ones that catch most people out, so it is worth pausing on them. According to the Planning Portal, outbuildings and garages must be single storey with a maximum eaves height of 2.5 metres and a maximum overall height of four metres with a dual pitched roof, or three metres for any other roof. The eaves height limit of 2.5 metres applies regardless of where the building sits. The overall height limit then depends on roof style: a traditional triangular pitch can reach 4 metres at the ridge, while a flat, pent, or mono-pitch roof is capped at 3 metres. Then there is a separate boundary rule: if any part of the building is within two metres of the property boundary, the entire structure must not exceed 2.5 metres in height, as confirmed by the government's own technical guidance. That 2.5 metre boundary limit therefore overrides the higher general limits whenever it applies.

Position and location rules

An outbuilding cannot be built forward of the principal elevation of the original house. The government's technical guidance makes clear that this rule also prevents permitted development anywhere in front of a hypothetical line drawn through the principal elevation to the side boundary. In most cases this means outbuildings are restricted to the rear and side gardens behind the front building line. The word original here is important: it refers to the house as it was first built, or as it stood on 1 July 1948 for properties built before that date.

The 50 percent coverage rule

One of the most commonly misunderstood limits is the 50 percent rule. The government's technical guidance states that the total area of ground around the house covered by buildings, enclosures, and containers must not exceed 50 percent of the total area of the curtilage, excluding the original house. Critically, this calculation includes not only any new outbuilding you are planning but also any existing outbuildings, any extensions already added to the house, and even detached buildings that were there when the house was built (such as an existing garage). If previous owners have already used up a significant portion of that allowance, your remaining room to build without permission may be smaller than you expect. The government's technical guidance specifically uses a detached garage or garden shed as an example of what must be counted.

Properties that cannot use these permitted development rights: flats, maisonettes, and converted houses

The permitted development allowances described in Class E apply to houses only. The Planning Portal is explicit that they do not apply to flats, maisonettes, or houses created through permitted development change of use rights (for example a former office converted to residential use under Schedule 2, Part 3). If you live in a flat or maisonette, or in a home that was originally something else and converted under a change of use, you will need to apply for full planning permission for any outbuilding regardless of its size or position. In Wales, the GOV.WALES guidance confirms the same position: the permitted development allowances described apply to houses, not flats, maisonettes, or other buildings.

Listed buildings

A listed building is one that has been placed on the National Heritage List for England (or the equivalent in Wales) because of its special architectural or historic interest. If your property is a listed building, the permitted development rights in Class E do not apply. The GOV.WALES guidance confirms you will need to apply for planning permission for construction of, or amendments to, any outbuildings within the curtilage of a listed building. You may also need separate Listed Building Consent for any works that affect the character of the listed structure, so it is essential to contact your LPA before starting any work.

Conservation areas and other designated land: National Parks, Areas of Outstanding Natural Beauty, the Broads, and World Heritage Sites

A conservation area is a place that a council has designated as having special architectural or historic character worth preserving. In National Parks, the Broads, Areas of Outstanding Natural Beauty, and World Heritage Sites, the permitted development rules are tighter. The Planning Portal confirms that in these areas the maximum area to be covered by buildings, enclosures, containers, and pools more than 20 metres from the house is limited to 10 square metres. Additionally, outbuildings to the side of the house on designated land will require planning permission rather than being permitted development. These restrictions mean that even a modestly sized garden structure may trigger the need for a full application if your property is in one of these areas.

Article 4 Directions: when permitted development rights are removed

An Article 4 Direction is a formal notice issued by a local planning authority that removes some or all permitted development rights from a defined area or class of property. According to the GOV.WALES guidance, these are most common in conservation areas where the character of an area could be threatened by unmanaged development. An Article 4 Direction can also arise from conditions attached to a previous planning permission on your specific plot. Your solicitor should have advised you at the time of purchase if an Article 4 Direction exists, but you can check with your LPA at any time. If one applies to your property, an outbuilding that would otherwise be permitted development will instead need a full planning application.

Use of your outbuilding: incidental and ancillary use only

For an outbuilding to fall within Class E, it must be used for a purpose incidental to the enjoyment of the dwellinghouse. The government's technical guidance explains that this means uses such as a garden shed, home office, hobby room, gym, or playroom used by the residents of the house. A purpose incidental to a house would not, however, cover normal residential uses such as separate self-contained accommodation or the use of an outbuilding for primary living accommodation such as a bedroom, bathroom, or kitchen. Using an outbuilding as a bedroom or installing a kitchen in it is likely to take it outside the PD rules and into the territory where full planning permission is needed, regardless of the building's size. If you want to run a business from an outbuilding, that too may require permission depending on the nature and scale of the activity, so it is worth checking with your LPA.

When you will need full planning permission

To summarise the situations where a full householder planning application is likely to be required rather than permitted development applying:

• The outbuilding is in front of the principal elevation of the original house.
• It exceeds the height limits (eaves above 2.5 metres, or overall height above 4 metres for a dual pitched roof or 3 metres for other roof types, or above 2.5 metres anywhere within 2 metres of a boundary).
• It would take the total built coverage of the curtilage beyond 50 percent.
• The property is a listed building.
• The property is a flat, maisonette, or converted house under Part 3 change of use rights.
• The property sits within a National Park, Area of Outstanding Natural Beauty, the Broads, or a World Heritage Site and the outbuilding is to the side of the house or has a floor area exceeding 10 square metres more than 20 metres from the house.
• An Article 4 Direction or a condition on a previous planning permission has removed Class E permitted development rights from your property.
• The outbuilding is intended to be used as self-contained living accommodation.

How to apply for planning permission for an outbuilding

If your outbuilding does need full planning permission, you will make a householder planning application to your local planning authority, most commonly online via the Planning Portal. You will generally need to supply a completed application form, a location plan showing the site in relation to surrounding roads and properties, a site plan showing the outbuilding in relation to the house and boundaries, and elevation drawings showing what the building will look like from each side. Your LPA may also require a fee. Councils aim to decide straightforward householder applications within eight weeks, though this can take longer during busy periods. Approval can come with conditions, such as restrictions on materials or hours of use. You have the right to appeal to the Planning Inspectorate if permission is refused.

Building Regulations: a separate requirement from planning permission

Even if your outbuilding is permitted development and needs no planning permission, you may still need to comply with Building Regulations. These are an entirely separate set of rules. As the government's technical guidance states, permitted development rights do not remove requirements for permissions or consents under other regimes such as the building regulations and the Party Wall Act. Building Regulations set minimum standards for structural integrity, fire safety, electrical safety, and energy efficiency. For most small detached garden buildings, Building Regulations do not apply, but thresholds matter. As a general guide, a detached outbuilding with a floor area under 15 square metres is unlikely to need Building Regulations approval. A building between 15 and 30 square metres may be exempt if it is at least one metre from any boundary or is built from substantially non-combustible materials. A building over 30 square metres will generally need Building Regulations approval. These thresholds are indicative: always confirm with your LPA or a Building Control body because the precise rules depend on how the building is used and how it is connected to services such as electricity.

Lawful Development Certificates: getting written confirmation

Even when you are confident your outbuilding is permitted development, you are not legally required to seek any formal approval. However, the government's technical guidance confirms it is possible to apply for a Lawful Development Certificate (LDC) from the local authority to be certain that a proposed development is lawful and does not require a planning application. An LDC is formal written confirmation from your LPA. It does not grant permission (no permission is needed for permitted development) but it proves that you do not need it. This distinction matters when you sell or remortgage your home, because conveyancing solicitors and mortgage lenders will routinely flag any structure that lacks either planning permission or a certificate of lawfulness. Applications for an LDC are submitted via the Planning Portal and require a completed form, plans showing the siting and dimensions of the structure, and a fee. Because the council is assessing a legal question rather than making a policy judgement, it cannot refuse a certificate simply because it dislikes the design: if the development meets the criteria, the certificate must be granted.

Wales: key differences to be aware of

Outbuilding rules in Wales are broadly similar to those in England but are set under separate Welsh legislation. The GOV.WALES guidance confirms that the permitted development rules for outbuildings in Wales apply to houses only, not to flats, maisonettes, or other buildings. Listed building restrictions apply in the same way: you will need planning permission for construction of, or amendments to, any outbuildings within the curtilage of a listed building. One notable Welsh specific rule is that no development can take place on land between the side elevation of the existing dwelling and the side boundary of your property in designated areas, and the total area of ground covered by outbuildings situated more than 20 metres from any wall of your dwelling cannot exceed 10 square metres in those areas. Article 4 Directions exist in Wales too and may have been applied in conservation areas or other sensitive locations. Always refer to the GOV.WALES outbuildings guidance and check with your Welsh LPA for the most current position.

Common outbuilding types: a quick reference

The following common project types all fall within the outbuilding rules described above, provided the conditions in Class E are met:

• Garden sheds and storage buildings: covered by Class E provided size, height, and position conditions are met.
• Detached garages: covered by the same rules as other outbuildings. An attached garage joined to the house is treated as an extension and different rules apply.
• Home offices and garden rooms: covered by Class E as long as the use remains incidental to the house and the building is not used as self-contained accommodation.
• Greenhouses: covered by the Planning Portal's outbuilding rules and subject to the same limits.
• Swimming pools and outdoor pools: covered by Class E and counted within the 50 percent coverage calculation.
• Home gyms and hobby rooms: covered by Class E when used by residents of the house for leisure purposes incidental to domestic life.
• Sauna cabins and summerhouses: specifically listed in the Planning Portal guidance as covered by the outbuilding rules.

This guide is general information, not advice on your specific case. Planning decisions turn on the facts of each property, so check with your local planning authority or apply for a Lawful Development Certificate where you need a definitive answer. Last reviewed 28/06/2026.