Adding an outbuilding can be an effective way to create extra space at home without extending the main property. Whether you want a garden office, workshop, storage building, home gym, or hobby room, understanding the permitted development rules for an outbuilding can help you determine whether you need planning permission.
Permitted development rights allow certain types of building work to proceed without a full planning application, provided the relevant conditions and limitations are satisfied. However, these rights are not unlimited. The proposed building’s dimensions, position, intended use and relationship with the existing house can all affect whether your project qualifies.
Before ordering a garden building or commissioning architectural drawings, it is worth checking the planning requirements that apply to your property. Taking this step early can help you avoid unnecessary design changes, delays and potential enforcement issues.
This guide explains how permitted development applies to outbuildings, which restrictions to consider and when professional planning advice may be beneficial.
What Is an Outbuilding Under Permitted Development?
An outbuilding is generally a separate structure within the grounds of a residential property. It is usually intended to support the use of the main home rather than operate as an independent property.
Common examples include:
The name given to a building does not automatically determine its planning status. Its actual use, design and relationship with the main house are important considerations.
For example, a garden office used by the household may qualify as permitted development if all applicable requirements are met. A building intended to operate as a separate home, however, raises different planning considerations.
Understanding this distinction is an important first step when assessing an outbuilding proposal.
Does an Outbuilding Qualify as Permitted Development?
Some outbuildings can be built without submitting a planning application because they fall within permitted development rights. However, the proposal must satisfy the relevant conditions and limitations.
There is no single rule that applies to every garden building. A structure that qualifies at one property may require planning permission at another because of differences in the site, existing development or planning restrictions.
Before proceeding, consider the following questions:
These questions help establish whether the project may fall within permitted development rights. Assess the proposal as a whole rather than relying on one measurement or assumption.
What Are the Main Permitted Development Rules for Outbuildings?
Several limitations can affect whether an outbuilding qualifies as permitted development. The precise requirements should be checked against the circumstances of the property and the current planning rules.
1. The Outbuilding Must Generally Be Single Storey
Under the relevant householder permitted development rules, an outbuilding must generally be single storey. A proposed two-storey garden building will usually need a different planning route.
This can affect projects where the homeowner wants to create a substantial studio, workshop or garden building with an upper floor.
If your design includes more than one storey, do not assume it can proceed under permitted development. A planning consultant can review the proposal and advise on the appropriate next steps.
2. Height Restrictions Must Be Satisfied
The permitted height of an outbuilding depends on its roof design and its position in relation to the boundary.
Generally, the maximum overall height may be:
The maximum eaves height is generally 2.5 metres.
These measurements can influence the shape and proportions of a proposed garden building. A design that appears suitable for the available space may need to be adjusted if it exceeds the relevant limits.
It is important to measure the proposed structure carefully and confirm which height restrictions apply before construction begins.
3. The Position of the Building Matters
An outbuilding cannot generally be positioned on land forward of a wall forming the principal elevation of the original house when relying on these permitted development rights.
This means that the proposed location should be considered before the design is finalised.
A building placed behind the main house may have a different planning position from one proposed at the front or side of the property. Additional restrictions can also apply to properties in designated areas.
A site plan showing the main house, boundaries, existing buildings and proposed outbuilding can help clarify the layout and identify potential issues.
4. Garden Coverage Must Be Considered
Permitted development rules generally limit how much of the land around the original house can be covered by extensions and other buildings. In broad terms, no more than half of that land can be covered by additions or other buildings.
This is not simply a calculation based on the proposed outbuilding alone. Existing extensions and other structures may also need to be taken into account.
For example, a property with a large rear extension, garage and several existing garden buildings may have less remaining allowance than a property with very little existing development.
Before choosing the size of a new outbuilding, review the existing layout and calculate the relevant coverage carefully.
5. Balconies, Verandas and Raised Platforms May Affect Eligibility
The permitted development rules also restrict certain features associated with outbuildings.
Verandas and balconies are not generally permitted under these rights. Raised platforms are also restricted, with the relevant rules limiting their height to 0.3 metres.
If your proposal includes a decked area, viewing platform or similar feature, check the requirements separately rather than assuming the whole project qualifies because the main building meets the size restrictions.
Does the Intended Use of an Outbuilding Matter?
Yes. The intended use is an important consideration when determining whether permitted development rights apply.
Outbuildings are generally expected to serve a purpose incidental to the enjoyment of the main dwelling. This can include household activities such as working, storage, exercise, hobbies and recreation.
However, a building intended to provide independent residential accommodation may fall outside the ordinary permitted development provisions for outbuildings.
Garden Offices and Workshops
A garden office, workshop or hobby room may qualify as permitted development if the building meets the relevant conditions and remains ancillary to the main home.
Calling a building an office or studio does not, by itself, establish that planning permission is unnecessary. The actual use and physical characteristics of the proposal still matter.
Outbuildings Used for Sleeping
If you intend to use an outbuilding for sleeping, the planning position should be checked carefully. The circumstances will depend on the design, use and relationship with the main dwelling.
A building designed to function as a self-contained living unit, particularly one with facilities for independent occupation, may require planning permission.
If you intend to accommodate a family member or create a separate annexe, it is advisable to establish the appropriate planning route before commissioning the design.
Do Property Type and Location Affect Permitted Development Rights?
Not every property benefits from the same permitted development allowances.
Flats and Maisonettes
The householder permitted development rights for outbuildings generally apply to houses rather than flats and maisonettes.
If you live in a flat or maisonette with access to a garden or shared outdoor space, do not assume that the same rules apply as they would to a house with its own garden.
The ownership and use of the land may also be relevant. Establish the planning position before arranging construction.
Listed Buildings
Additional restrictions apply to listed buildings and their settings. An outbuilding within the curtilage of a listed building will generally require planning permission, and other heritage-related consent may also be relevant depending on the proposal.
If your property is listed, seek advice before relying on permitted development rights.
Designated Areas
Properties in certain designated areas can be subject to additional limitations. The applicable restrictions depend on the designation and the location of the proposed building.
The property’s planning history and any relevant restrictions should be reviewed before the design is finalised. Meeting the standard dimensions alone does not guarantee that an outbuilding can proceed without planning permission.
What If Your Outbuilding Does Not Meet the Permitted Development Rules?
If a proposed outbuilding falls outside the relevant permitted development limits, this does not automatically mean that the project cannot go ahead.
Instead, it may mean that a planning application is required. The appropriate approach will depend on the design, location, intended use and planning circumstances of the site.
In some cases, adjusting the dimensions, position or design may help bring a proposal within the applicable requirements. In other cases, submitting a planning application may be the more appropriate option.
A planning consultant can review the proposal, identify the relevant constraints and explain the available routes before you commit to construction.
For projects involving garages, it may also be useful to read our guide to planning permission for a garage, which explores planning considerations associated with this type of building.
Can You Obtain a Lawful Development Certificate for an Outbuilding?
A Lawful Development Certificate can provide formal confirmation of the planning status of a proposed or existing development where the legal requirements are satisfied.
For a proposed outbuilding, an application may be appropriate where you want confirmation that the development would be lawful if carried out as described. The application generally needs to include sufficient information to establish the proposal and demonstrate why it qualifies.
This may involve plans, measurements, site information and details of the intended use.
A certificate is not a substitute for planning permission where permission is required. However, it can provide useful written evidence of the planning position.
Whether an application is appropriate will depend on the specific circumstances of your project.
What Happens If You Build Without Checking Planning Permission?
Starting work before establishing the planning position can create avoidable complications.
If an outbuilding requires planning permission and has been constructed without it, the local planning authority may investigate the development. Depending on the circumstances, you may need to consider a retrospective planning application or other steps to address the issue.
There is no guarantee that retrospective permission will be granted. If permission is refused and enforcement action is taken, alterations or removal of the building may be required.
Checking the planning requirements before construction allows you to address potential problems while the design can still be changed.
It is also important to remember that planning permission and Building Regulations are separate matters. Depending on the building’s size, construction and intended use, Building Regulations may need to be considered even where planning permission is not required.
How to Check Whether Your Outbuilding Qualifies
Before ordering a building or starting work, take time to review the proposal.
Step 1: Confirm the property details. Establish the property type and check whether any restrictions affect the site.
Step 2: Prepare accurate measurements. Record the proposed dimensions, roof design, eaves height and distance from the boundaries.
Step 3: Review the garden layout. Identify existing extensions, garages and other structures that may affect the permitted coverage calculation.
Step 4: Clarify the intended use. Consider whether the building will support the main household or is intended to provide independent accommodation.
Step 5: Check the planning history. Previous permissions and conditions may affect the planning position.
Step 6: Seek advice where necessary. If any requirement is unclear, obtain professional guidance before committing to the project.
This process can help you identify potential planning issues early and determine whether further checks or an application may be needed.
How Expert Planning Consultants Can Help
Although permitted development can offer a straightforward route for some outbuilding projects, applying the rules correctly requires consideration of the complete proposal and the property’s circumstances.
At Expert Planning Consultants, we can review your proposed outbuilding, assess the relevant planning considerations and advise on the most appropriate route forward.
Depending on your project, this may involve reviewing the site layout, proposed measurements, existing development, intended use and relevant planning history. Where planning permission is required, we can also discuss the next steps involved in preparing a suitable application.
Obtaining advice before construction can help you understand your options, identify potential constraints and avoid relying on assumptions that may not apply to your property.
Frequently Asked Questions About Permitted Development Outbuildings
Do all outbuildings qualify as permitted development?
No. An outbuilding must meet the relevant conditions and limitations to qualify. Its dimensions, location, intended use, property type, and any applicable restrictions all need to be considered.
Can I build an outbuilding without planning permission?
It may be possible if the proposed building falls within permitted development rights and satisfies all the applicable requirements. If it does not, planning permission may be necessary.
How close can an outbuilding be to a boundary?
An outbuilding can potentially be positioned close to a boundary, but additional height restrictions generally apply when it is within two metres of the boundary. The full proposal should be checked against the relevant rules.
Can I use a permitted development outbuilding as a garden office?
A garden office may qualify where the applicable conditions are met and the use remains ancillary to the main dwelling. The description of the building alone does not determine its planning status.
Can I build an outbuilding for a family member to live in?
An outbuilding intended to provide independent residential accommodation may require planning permission. If you plan to create an annexe, establish the planning requirements before construction begins.
Do I need a Lawful Development Certificate?
A certificate is not automatically required for every outbuilding. However, it may provide formal confirmation of the planning status of a proposed or existing development where the relevant legal requirements are met.
Does permitted development mean Building Regulations do not apply?
No. Planning permission and Building Regulations are separate. Building Regulations may apply depending on the building’s construction, size and intended use.
Plan Your Outbuilding Project With the Right Advice
Permitted development rights can make it possible to add useful space to your property without a full planning application. However, the rules for outbuildings involve more than simply choosing a building that fits in your garden. Height, position, garden coverage, intended use and property-specific restrictions can all affect the outcome.
Before proceeding, it is worth establishing whether your proposed outbuilding meets the relevant requirements or whether a different planning route is needed.
Contact us today to discuss your outbuilding project and obtain professional planning advice before work begins. We can help you review your proposal, understand the planning considerations, and identify the most suitable next steps.