House extensions, conservatories and porches are popular ways to improve a property, create additional space and make a home more practical. Whether you want a larger kitchen, a bright garden room or a covered entrance, it is important to understand the planning rules before starting construction.
Some projects can be completed under permitted development rights without a formal planning application. Others require planning permission because of their size, location, design or impact on neighbouring properties. Separate building regulations may also apply, even when planning permission is not required.
This article explains the planning permission requirements for house extensions, conservatories and porches in England, including the main permitted development rules, common restrictions and steps to take before beginning your project.
Do House Extensions, Conservatories and Porches Need Planning Permission?
Not always. Under permitted development rights, certain home improvements can be carried out without submitting a planning application, provided they meet specific limits and conditions.
The rules differ depending on the type of project. A rear extension, for example, is assessed differently from a porch at the front entrance. Conservatories generally follow the same planning rules as other house extensions.
However, permitted development rights do not apply in every situation. Restrictions may affect properties in conservation areas, listed buildings, flats and maisonettes, or homes where permitted development rights have been removed or limited.
Before deciding whether you need permission, consider the proposed size, height, position and appearance of the structure, as well as any previous extensions to the property.
You can use Planning Build’s guidance on whether you need planning permission to understand the initial checks involved.
Planning Permission for House Extensions
A house extension can provide additional living space without the need to move. Common examples include single-storey rear extensions, side extensions and larger additions across more than one floor.
In England, some extensions fall within permitted development rights. However, they must comply with the relevant limitations and conditions.
Size and Height Restrictions
Permitted development rules place limits on the dimensions and position of house extensions. The applicable limits depend on the design and location of the proposed addition.
For example, a single-storey rear extension may be permitted without a planning application if it meets the relevant limits for depth, height and boundary distances. Larger extensions may require a separate prior approval process, while proposals outside the permitted development limits will generally need planning permission.
Other important restrictions include:
- Extensions must not exceed the permitted height limits.
- Eaves height is restricted where an extension is close to a boundary.
- Extensions generally cannot extend beyond the principal elevation or a side elevation that fronts a highway.
- The total area of land around the original house covered by extensions and other buildings must not exceed the applicable limit.
- Certain features, including balconies and raised platforms, are not permitted under the standard householder extension rights.
The rules consider the original house and previous enlargements, not simply the new extension in isolation. An addition built by a previous owner may therefore affect the permitted development allowance available to you.
For the detailed limits, consult the Planning Portal’s guidance on extensions.
When Does a House Extension Require Planning Permission?
You may need a planning application if your extension exceeds permitted development limits, affects a property with restricted development rights or falls outside the relevant rules for the type of house or site.
Planning permission may also be needed where a property is listed or subject to specific planning conditions. Listed building consent may be required for alterations affecting a listed building, even where a separate planning permission assessment is also necessary.
If your proposal needs an application, a householder planning application is commonly used for qualifying alterations or extensions to an existing house.
Planning Build can help you understand the householder planning application process and the information that may be required.
Planning Permission for Conservatories
A conservatory can create additional living space while allowing more natural light into your home. Although conservatories often have extensive glazing and a different appearance from conventional extensions, they generally fall under the same planning rules as other house extensions.
This means that the proposed conservatory must comply with the relevant permitted development limits and conditions if you want to build it without a planning application.
When Can You Build a Conservatory Without Planning Permission?
A conservatory may be permitted development when its size, height and position meet the applicable requirements.
Factors to consider include:
- How far the conservatory extends beyond the original rear wall.
- Whether it is attached to the side or rear of the house.
- Its overall height and proximity to boundaries.
- The amount of land around the original house already covered by buildings and extensions.
- Whether previous extensions have used some of the permitted development allowance.
- Whether restrictions apply to the property or its location.
The fact that a conservatory is made primarily from glass does not automatically exempt it from planning permission. Its dimensions and position remain important.
Do Conservatories Need Planning Permission in Restricted Areas?
Properties in conservation areas and other designated locations may have additional restrictions. A listed building may require listed building consent for work affecting its character, and permitted development rights may have been removed through a planning condition or an Article 4 Direction.
If you are planning a conservatory on a property with these restrictions, check the position before commissioning detailed designs or arranging construction.
You can find further information in the Planning Portal’s conservatory guidance.
Planning Permission for Porches
A porch can provide a sheltered entrance, extra storage space and protection from the weather. In England, a porch outside an external door of a house can usually be built under permitted development rights if it meets three main conditions.
The porch must:
- Have a ground-floor area of no more than 3 square metres, measured externally.
- Be no more than 3 metres high above ground level.
- Be at least 2 metres from any boundary of the property that fronts a highway.
If any of these limits is exceeded, planning permission may be required.
These allowances apply to qualifying houses, not automatically to flats, maisonettes or every type of converted property. Restrictions on permitted development rights can also affect whether the rules are available.
Before building a porch, check the proposed measurements and the position of the entrance in relation to the road and property boundaries.
For more detail, read the Planning Portal’s guidance on porches.
What Other Factors Can Affect Planning Permission?
Even where a project appears to fall within permitted development limits, additional considerations may affect what you can build.
Property Location and Restrictions
The location of your property can affect the permitted development rights available. Conservation areas, listed building status, planning conditions and Article 4 Directions may restrict otherwise permitted work.
If you live in a flat or maisonette, do not assume that the permitted development rules for houses apply to your property.
The Impact on Neighbours
The design and position of an extension can affect neighbouring properties through overlooking, loss of light, increased sense of enclosure or changes to the character of the street.
These considerations may be relevant when a planning application is assessed. Addressing them during the design stage can help you develop a proposal that responds to the surrounding area.
Previous Extensions
Previous alterations can affect the permitted development allowance remaining for your property. Check the history of the house, including additions completed by previous owners, before relying on permitted development rights.
Building Regulations
Planning permission and building regulations are separate requirements. A project that does not need planning permission may still need building regulations approval.
Building regulations address matters such as structural safety, fire safety, energy efficiency and other technical standards. Some conservatories and porches may qualify for exemptions from certain building regulations requirements, but these exemptions have specific conditions.
Check the applicable requirements with your building control body before work begins.
How to Check Whether Your Project Needs Planning Permission
Before building a house extension, conservatory or porch, follow these steps to establish which requirements apply.
1. Define your proposal. Establish the intended size, height, location and design of the addition.
2. Check the property’s planning history. Previous extensions and planning conditions may affect the options available.
3. Review the relevant permitted development rules. Compare your proposed dimensions and position against the official guidance for the type of work.
4. Check for additional restrictions. Establish whether the property is listed, lies within a conservation area or is affected by an Article 4 Direction.
5. Seek professional advice if necessary. If the rules are unclear or your proposal is close to a permitted development limit, obtain guidance before starting construction.
6. Prepare an application if required. If your proposal falls outside permitted development rights, you may need to submit a planning application with the appropriate drawings and supporting information.
Planning Build’s planning permission services can help you understand the requirements relevant to your proposed development.
Frequently Asked Questions
Can I build a rear extension without planning permission?
Yes, some rear extensions fall within permitted development rights in England. The extension must meet the relevant size, height, position and other conditions. Larger proposals may require prior approval or planning permission.
Does a conservatory have the same planning rules as an extension?
Generally, yes. Conservatories are subject to the same main permitted development rules as other house extensions. Their glazed construction does not automatically remove the need to comply with planning restrictions.
What is the maximum size of a porch without planning permission?
Under the standard permitted development rules in England, a porch must not exceed 3 square metres in external ground-floor area or 3 metres in height. It must also be at least 2 metres from a boundary with a highway. Other restrictions may apply.
Do I need planning permission for a porch on a listed building?
You should check the specific requirements before proceeding. Listed building consent may be required for work affecting the building’s character, and planning permission may also be necessary depending on the proposal and applicable restrictions.
Can I start building while waiting for planning permission?
You should not begin work that requires planning permission until the necessary permission has been granted. Starting without the required approval can lead to enforcement action and additional costs.
Get Advice Before Starting Your Home Improvement Project
House extensions, conservatories and porches can improve the space and functionality of your home, but the planning requirements depend on the details of your proposal and the property itself.
Checking permitted development rights, reviewing previous alterations and identifying any restrictions early can help you understand whether you need planning permission and what steps to take next.
If you are unsure about the requirements for your project, contact Planning Build to discuss your proposal and the planning support that may be appropriate.
