A Simple Guide for Homeowners
Many homeowners in the UK can extend their homes without needing to apply for full planning permission. This is possible because of something called permitted development rights.
However, these rights come with strict limits and conditions, and they do not apply to every property. Understanding how they work can help you avoid costly mistakes before starting an extension.
This guide explains the basics of permitted development and when you may still need planning permission.
What Are Permitted Development Rights?
Permitted development (often shortened to PD) is a set of national planning rules that allow certain types of development to take place without submitting a full householder planning application.
These rules are set out in the Town and Country Planning (General Permitted Development) Order.
For homeowners, permitted development commonly covers things like:
- Rear house extensions
- Small side extensions
- Loft conversions
- Outbuildings such as garden rooms
- Some roof alterations
- Porches and small external changes
However, these rights only apply if your proposal stays within strict size and design limits.
Common Permitted Development Limits for Extensions
While the exact rules can vary depending on the project, some typical limits include:
Rear Extensions
For detached houses:
- Up to 4 metres beyond the rear wall of the original house
For semi-detached and terraced houses:
- Up to 3 metres beyond the rear wall
Under the larger home extension permitted development rights, these limits can sometimes increase to:
- 8 metres for detached houses
- 6 metres for semi-detached and terraced houses
These larger extensions require the submission of a Prior Approval application before works can start. You can not apply for Large Home Extension Prior Approval retrospectively. If you do not submit a Prior Approval application before starting works, you will require householder planning permission to regularise works.
Height Restrictions
Extensions must not be higher than the existing house and must usually stay within:
- 4 metres maximum height for single-storey extensions
- Lower eaves heights near boundaries
Materials
Materials used in the extension should be similar in appearance to the existing house. Alternatively a conservatory is also acceptable under permitted development.
Land Coverage
Permitted development rules generally require that at least half of the land within the curtilage of the property remains undeveloped. The curtilage area is usually made up of the land within the front and rear garden area, however this is dependent on specific on-site circumstances.
When Permitted Development Does NOT Apply
Many homeowners assume permitted development automatically applies, but this is not always the case.
Permitted development rights may be restricted or removed if:
- The property is in a Conservation Area
- The property is in a National Park
- The property is in an Area of Outstanding Natural Beauty
- The home is a listed building
- The property is a flat or maisonette
- Planning conditions have removed permitted development rights
You can read more about this in our guide:
Why Permitted Development Rights May Not Apply to Your Property
Previous Extensions Can Affect Your Rights
Permitted development limits are calculated based on the original house, not the current one.
This means that:
- Previous extensions count towards the limits
- Outbuildings may affect garden coverage
- Alterations made by previous owners can affect what you can build today
Because of this, many homeowners accidentally assume they can build more than the rules allow.
Why Many Homeowners Still Apply for a Lawful Development Certificate
Even if your extension qualifies as permitted development, many homeowners choose to apply for a Lawful Development Certificate (LDC).
This provides official confirmation from the council that the development is lawful.
Benefits include:
- Peace of mind before building starts
- Proof for future buyers when selling the property
- Protection from planning enforcement issues
You can learn more about this service here:
Lawful Development Certificate Application Support
Get Professional Advice Before You Start
Permitted development rules can be complex, and small details can make a big difference.
Before committing to drawings or construction, it’s often worth confirming the planning position of your property.
A Home Extension Planning Report provides:
- A review of your property’s planning history
- Confirmation of permitted development rights
- Advice on what you can realistically build
- Identification of planning risks
Order a Home Extension Planning Report
Related Guides for Homeowners
You may also find these guides useful:
- Do I Need Planning Permission for My Extension?
- Why Permitted Development Rights May Not Apply to Your Property
- Common Extension Mistakes That Trigger Planning Refusals
- 5 Things to Check Before Starting a Home Extension