Outbuildings are a popular addition to many residential properties across the UK, providing valuable extra space for a variety of purposes, from home offices and gyms to workshops and summerhouses. If you are considering an outbuilding project, understanding the rules surrounding planning permission for outbuildings in the UK is essential.
Depending on the size, location, design and intended use of your proposed outbuilding, you may be able to construct it under Permitted Development (PD) rights without submitting a full planning application. However, certain properties and locations are subject to additional restrictions.
This guide explains the key planning rules for outbuildings, when planning permission may be required, Permitted Development requirements, building regulations and other important considerations.
What Is Considered an Outbuilding?
In planning terms, an outbuilding is a structure located separately from the main house but within its garden or property boundary, known as the curtilage.
Common examples of outbuildings include:
- Garden sheds
- Garages
- Carports
- Greenhouses
- Garden offices
- Studios
- Workshops
- Summerhouses
- Garden rooms
- Home gyms
An outbuilding can provide useful additional space without extending the main house. However, its planning status will depend on factors such as its size, position, appearance and intended use.
What Can an Outbuilding Be Used For?
Outbuildings can generally be used for purposes that are incidental to the enjoyment of the main dwellinghouse. This could include a home office, hobby room, gym, storage area or workshop.
The distinction between incidental use and independent residential accommodation is important. An outbuilding intended to function as a separate home, holiday let or independent living unit may require planning permission.
Do You Need Planning Permission for an Outbuilding?
In many cases, an outbuilding can be constructed without planning permission under Permitted Development rights. However, the development must meet the relevant conditions and limitations.
The rules are not identical for every property. Permitted Development rights can be restricted or removed by planning conditions, Article 4 Directions, the property’s location or its status.
If your proposal does not comply with the applicable PD requirements, you may need to submit a planning application to your local planning authority.
Permitted Development Rights for Outbuildings
Permitted Development rights allow certain types of development to take place without the need for a full planning application.
For residential outbuildings, the relevant rules generally apply to structures within the curtilage of a dwellinghouse, provided the applicable conditions are satisfied.
Key Permitted Development Criteria for Outbuildings
The main requirements include the following:
Single-Storey Construction
The outbuilding must be single storey.
Height Restrictions
The applicable height limits depend on the type of roof and the building’s position.
Generally:
- The eaves should not exceed 2.5 metres in height.
- The overall height should not exceed 4 metres for a dual-pitched roof.
- The overall height should not exceed 3 metres for other types of roof.
- Where the building is within 2 metres of a boundary, the maximum overall height is generally 2.5 metres.
Careful measurements are therefore essential when designing an outbuilding close to a neighbouring boundary.
Intended Use
The building must be used for purposes incidental to the enjoyment of the dwellinghouse.
It should not normally be used as an independent dwelling or separate residential accommodation under these rights.
Coverage of the Garden
The development must comply with the limitation relating to the amount of land around the original house that can be covered by additions or other buildings.
Generally, no more than 50% of the area of land around the original house can be covered by additions or other buildings.
The definition of the “original house” is important when assessing this requirement.
Position of the Outbuilding
An outbuilding should not normally be positioned in front of the principal elevation of the original house.
This can be particularly important for properties where the front garden provides the proposed location for a garage, office or other structure.
When Are Permitted Development Rights Restricted?
Not every residential property benefits from unrestricted Permitted Development rights.
Additional restrictions may apply where the property is:
- A listed building
- Located within a conservation area
- Located within a National Park
- Located within the Broads
- Located within an Area of Outstanding Natural Beauty
- Located within a World Heritage Site
- A flat or maisonette
Article 4 Directions and planning conditions can also remove or restrict certain Permitted Development rights.
Outbuildings for Flats and Maisonettes
The Permitted Development rights available to houses do not generally apply in the same way to flats and maisonettes.
If you own or occupy a flat or maisonette and are considering constructing an outbuilding, you should seek specific planning advice before starting work.
When Does an Outbuilding Require Planning Permission?
Planning permission may be required where the proposed structure does not comply with the applicable Permitted Development conditions.
Examples can include:
- An outbuilding exceeding the relevant height limits
- A structure that is too large or does not comply with the applicable coverage restrictions
- An outbuilding positioned where Permitted Development rights do not allow it
- A building intended to provide independent residential accommodation
- Development on a property where PD rights have been removed
- Certain proposals affecting listed buildings or designated areas
- A proposal involving a material change of use
The precise requirements depend on the circumstances of the property and development.
Planning Considerations for an Outbuilding
Where planning permission is required, the local planning authority will assess the proposal against relevant planning policies and material considerations.
Impact on Neighbours
The authority may consider whether the proposed outbuilding would cause:
- Loss of privacy
- Overshadowing
- Loss of light
- An overbearing impact
- Noise or disturbance
- Other adverse effects on neighbouring properties
Design and Appearance
The size, scale, design and materials of an outbuilding can influence the planning assessment.
A structure that is appropriately designed and proportionate to the garden is more likely to integrate successfully with the existing property and surrounding area.
Heritage Considerations
Additional considerations may apply where the property is listed or located within a conservation area or another designated heritage setting.
Listed building consent may also be required for works affecting a listed building or its setting, depending on the circumstances.
How Do You Apply for Planning Permission for an Outbuilding?
If planning permission is required, an application will normally be submitted to the relevant local planning authority, often through the Planning Portal.
The application may require:
- A completed planning application form
- Site location plans
- Block plans
- Existing and proposed floor plans
- Elevation drawings
- Design and access information where applicable
- Supporting documents
- The relevant planning application fee
How Long Does Planning Permission Take?
The timescale for a planning application can vary depending on the proposal, local authority and whether additional information is required.
Once an application has been submitted and validated, the local planning authority will assess it and may consult neighbours and relevant statutory consultees.
If planning permission is refused, there may be a right of appeal depending on the circumstances.
Lawful Development Certificates for Outbuildings
If you believe your proposed or existing outbuilding benefits from Permitted Development rights, you may wish to consider applying for a Lawful Development Certificate (LDC).
An LDC is not the same as planning permission. Instead, it provides formal confirmation from the local planning authority that the proposed or existing development is lawful in planning terms.
Although an LDC is not always legally required before carrying out permitted development, it can provide useful evidence of the property’s planning position, particularly if you intend to sell or refinance the property.
Building Regulations for Outbuildings
Planning permission and Building Regulations are separate matters.
Planning controls issues such as the use, appearance, location and impact of a development, whereas Building Regulations address matters such as structural safety, insulation, ventilation, fire safety and construction standards.
Some smaller outbuildings may be exempt from Building Regulations, depending on their size, use, construction and distance from boundaries.
When Might Building Regulations Apply?
Building Regulations may become relevant where an outbuilding:
- Is used for sleeping accommodation
- Exceeds applicable size thresholds
- Is constructed in a way that does not qualify for an exemption
- Includes certain structural or building systems requiring approval
Electrical installations and plumbing may also be subject to separate regulatory requirements.
You should check with your local building control body or a suitably qualified professional before construction begins.
Common Uses for Outbuildings in the UK
Outbuildings can serve a wide range of purposes.
Home Offices
Garden offices have become increasingly popular as more people work remotely or operate businesses from home.
Workshops and Studios
An outbuilding can provide dedicated space for hobbies, crafts, artistic work or other activities that may be difficult to accommodate within the main house.
Home Gyms
A garden gym can provide a convenient private space for exercise without requiring a separate gym membership.
Storage
Sheds, garages and storage buildings remain some of the most common types of outbuilding.
Leisure Spaces
Summerhouses, hobby rooms and family recreation spaces can provide additional usable areas within a garden.
The intended use should always be considered carefully because an outbuilding used as independent residential accommodation may require planning permission.
Outbuildings Used as Accommodation
One of the most important planning considerations is whether an outbuilding is genuinely ancillary to the main house or is effectively being used as a separate dwelling.
A garden building containing facilities such as a kitchen, bathroom and sleeping accommodation may attract greater planning scrutiny, particularly if it can function independently from the main house.
Can You Build a Garden Annexe Without Planning Permission?
A garden annexe or self-contained accommodation will generally require careful consideration and may require planning permission.
If you are proposing an annexe for a family member, guest accommodation or another residential purpose, it is advisable to establish the planning position before construction begins.
Design Tips for Outbuildings
Good design can help your outbuilding integrate with the property and surrounding area.
Keep the Building Proportionate
Consider the size of the garden and the scale of the existing house. An outbuilding should not unnecessarily dominate the available outdoor space.
Choose Appropriate Materials
Using materials and finishes that complement the existing property can help the structure blend into its surroundings.
Consider Neighbouring Properties
Think carefully about windows, height and positioning to minimise potential privacy, overlooking and overshadowing concerns.
Consider Landscaping
Trees, planting and other landscaping can help soften the visual impact of an outbuilding.
Plan Access Carefully
Make sure there is safe and practical access to the structure, particularly where it will be used as a workshop, garage or storage area.
What Happens If You Build an Outbuilding Without Planning Permission?
If planning permission was required but was not obtained, the local planning authority may investigate the development and consider enforcement action.
Depending on the circumstances, this could require the owner to submit a retrospective planning application or take steps to remedy or remove the unauthorised development.
It is therefore important to establish whether planning permission or another form of approval is required before construction begins.
Planning Permission for Outbuildings UK: Frequently Asked Questions
Do I need planning permission for a garden shed?
Not necessarily. A garden shed may fall within Permitted Development rights if it meets all applicable conditions and limitations. The size, height, position, intended use and location of the property should be checked before construction.
How big can an outbuilding be without planning permission in the UK?
There is no single maximum size that applies to every outbuilding. Permitted Development rules include requirements relating to the amount of garden that can be covered, height, location and use. The specific circumstances of the property must therefore be assessed.
Can I build an outbuilding close to my neighbour’s boundary?
You may be able to, but additional height restrictions apply where an outbuilding is within 2 metres of a boundary under the relevant Permitted Development rules. Other planning considerations may also apply.
Can I use my garden office as a bedroom?
Using an outbuilding for sleeping accommodation can change the planning and Building Regulations position. A building intended to provide independent or residential accommodation may require planning permission and additional approvals.
Can an outbuilding have a toilet or bathroom?
The installation of plumbing does not automatically determine whether planning permission is required. However, a bathroom, kitchen or other facilities may indicate that the building is capable of independent use, so the overall use and circumstances should be carefully considered.
Can I build an outbuilding in a conservation area?
Possibly. Some Permitted Development rights continue to apply in conservation areas, but additional restrictions can apply depending on the type and location of the development. You should check with the relevant local planning authority before proceeding.
Do I need planning permission for a garden gym?
A garden gym may be permitted development if the building satisfies the relevant conditions and is used for a purpose incidental to the enjoyment of the main dwellinghouse. Planning permission may be required if the proposal falls outside those rights.
Do I need planning permission for a garden office?
A garden office can potentially be built under Permitted Development rights if the relevant conditions are satisfied. Its use should remain incidental to the main dwelling rather than becoming a separate residential unit.
What is the difference between planning permission and a Lawful Development Certificate?
Planning permission authorises development that requires consent, subject to the conditions attached to the permission. A Lawful Development Certificate provides formal confirmation that an existing or proposed development is lawful in planning terms.
What happens if my outbuilding does not comply with Permitted Development rules?
If an outbuilding does not meet the relevant PD conditions, planning permission may be required. If the structure has already been built without the necessary permission, you may need to consider a retrospective planning application or other steps to address the planning breach.
Do outbuildings need Building Regulations approval?
Not always. Some smaller outbuildings can benefit from Building Regulations exemptions, depending on their size, use, construction and location. However, larger buildings or those intended for sleeping accommodation may require Building Regulations approval.
Can I convert an existing garage into living accommodation?
Converting a garage into habitable or independent accommodation can involve both planning and Building Regulations considerations. Whether planning permission is required depends on the proposed use, the existing planning position and any restrictions affecting the property.
Get Expert Advice on Planning Permission for Outbuildings
Understanding planning permission for outbuildings in the UK is important before you invest in a garden office, gym, workshop, garage, summerhouse or other garden structure.
While many residential outbuildings can benefit from Permitted Development rights, the rules are subject to specific conditions and limitations. Restrictions may also apply to listed buildings, flats, conservation areas and properties affected by Article 4 Directions or planning conditions.
Getting the planning position right at the outset can help you avoid unnecessary costs, delays and potential enforcement action.
If you are unsure whether your proposed outbuilding requires planning permission, or you need advice on Permitted Development, a Lawful Development Certificate or a planning application, Charrette Law can help.
Contact Charrette Law today for expert guidance on planning permission for outbuildings across the UK. Our team can assist with assessing your proposal, understanding applicable planning restrictions and preparing for the appropriate planning process.
