Find out if you need planning permission

You may need planning permission to make improvements or changes to a property.

It is important to find out whether you need planning permission before you make any changes. If you go ahead without permission, you may end up having to put things back to how they were.

Some minor alterations and extensions, particularly to houses, can be carried out without planning permission. This is called permitted development.

There are no permitted development rights for flats.

This step by step list will help you find out if the work you have in mind can be carried out without planning permission:  

Visit the Planning Portal

Check the guidance on the Planning Portal

If this shows that your project comes under permitted development you still need to complete steps 2 and 3 below.

If you do need planning permission, make sure you read Apply for planning permission.

Check for planning conditions and constraints on your property

Even if your proposal is covered by permitted development you must also check if the permitted development rights have been removed or restricted by us. This can be by either conditions or constraints. If this is the case, you may still have to apply for planning permission. 

Planning conditions on your property

What you can build under permitted development may be affected:

  • by any existing planning conditions relating to your property
  • if the permitted development rights have been removed or restricted

Use our planning history search to check the planning history for your property.

Check planning history

Planning constraints on your property

Your permitted development rights may be affected if your property is:

  • in a conservation area
  • a listed building
  • in an area where there is an Article 4 Direction

Check for planning constraints

You will need to make additional checks if you have to apply for planning permission.

Next steps

If you believe your proposal is:

Permitted development without any conditions or constraints

If your proposal is covered by permitted development and there are no planning conditions, Article 4 Directions, and the property is not a listed building or in a conservation area you do not need to apply for planning permission. 

If you would like proof that this is the case you can apply for a Lawful Development Certificate

Before you start your project you should check if you need to submit an application for building regulations - you may still need to do this even though you do not require planning permission.

Permitted development but with constraints

If your proposal is covered by permitted development but it:

  • affects a listed building you’ll need to apply for listed building consent
  • involves demolition in a conservation area you’ll need to apply for conservation area consent
  • is covered by an Article 4 Direction you need to check if this is relevant to your proposal.  If it is you’ll need to make a planning application.  If you are unsure if it is relevant contact

For all of the above you’ll also need to check if an application for building regulations is required.

Not permitted development or there are planning conditions restricting what you can do

You can either:

You’ll also need to check if an application for building regulations is required.

In addition, if it affects a listed building or involves demolition in a conservation area, as part of your planning permission you’ll need to apply for: 

  • listed building consent
  • conservation area consent

If you are still unsure

Ask us to advise whether planning permission is required by applying for a Lawful Development Certificate.  There is a fee for this service.

Prior approval

For some work which is permitted development, including larger householder extensions and some change of use, you’ll still need to notify us through the prior approvals process.

Find out when you need to get prior approval

The prior approvals process is simpler than applying for full planning permission.

Large single storey extensions

Large single storey extensions may be permitted development, but you’ll need to notify us if you are going to build one. This applies to extensions of between 4 and 8 metres for a detached house, or between 3 and 6 metres for all other houses. See more information on the Planning Portal on prior approval for large single storey extensions.

Change of use

You’ll also need to notify us for some changes of use. See the Planning Portal for details of which types of change of use are subject to prior approval.

Forestry, agricultural, telecommunications and demolitions

See the Planning Portal guidance notes on prior approval for forestry, agricultural, telecommunications or demolitions work.

Lawful Development Certificate

You can apply for a Lawful Development Certificate to get proof that your proposed use or development of a building does not require planning permission. 

This is useful if you should later sell your property as it can answer questions raised by potential buyers or their legal representatives.

We are unable to offer this advice over the telephone or via email.  You must make an application.

After receiving your application we aim to get back to you within 8 weeks.

If permission is not required you’ll be issued with a certificate confirming this. If planning permission is required, you’ll then need to continue onto a formal application.

How to apply for a Lawful Development Certificate

Go to apply for planning permission. Please make sure you include all the supporting information shown in the relevant validation requirements.

Other types of permission

Dropped kerbs

A dropped kerb is the lowered kerb that allows you to access your property from the road by driving across the pavement. It is also known as a vehicle crossover.

You must apply for planning permission from us for a dropped kerb that is joining an A, B or C classified road, for example A259, B2140, C546.

All classifications of roads will need approval from West Sussex County Council for a dropped kerb.

If your road is private (P) you’ll also need permission from all owners of the road (either residents or developers depending on circumstances).

If you do not own the property you’ll also need consent from the owner.

To apply for a dropped kerb:

  1. Check the classification of your road by visiting WSCC (select Local Information/Road Status on the left).
  2. If your road is A, B or C classification you must apply for planning permission using either the standard householder application form or, for flats or businesses, the full planning application form. Please also check the householder planning validation requirements[pdf] 196KB  in particular the information on visibility splays.
  3. Request approval from West Sussex County Council Highways (for all road classifications).

South Downs National Park (SDNP)

If you are making an application for a site that lies within the South Downs National Park you’ll need to make your application directly to them.

Using a planning agent

The planning process can be complex and you may want to appoint a planning agent to act on your behalf. If you do appoint an agent all communication will be with them. We cannot recommend agents but you can find a list of registered agents at Royal Town Planning Institute (RTPI).

For further advice see choosing an agent.


The Planning Duty Officer is no longer available. Helpful advice can be found in the duty planner guidance [pdf] 3MB. Some advice can be obtained from our contact centre.

Phone 01903 737756

You can get 15 minutes of free planning advice for communities and members of the public (not businesses) from Planning Aid