Do I Need Planning Permission for a Rear Extension in Worthing?
One of the most common questions homeowners ask when considering a rear extension is whether planning permission will actually be required.
The answer is — not always.
Many rear extensions across Worthing and West Sussex can often be carried out under what’s known as permitted development, allowing certain types of residential work to proceed without full planning permission. However, this depends on a number of factors including the size of the extension, the type of property and whether any planning restrictions already affect the home.
Understanding the difference early on can help homeowners approach projects with much more clarity and confidence before progressing into drawings and construction costs.
What Is Permitted Development?
Permitted development rights allow homeowners to carry out certain types of residential work without submitting a full householder planning application.
For rear extensions, this can often include:
Single-storey rear extensions
Smaller side extensions
Certain roof alterations
Some loft conversions
Internal layout changes
However, strict size and design limitations apply, and permitted development rights can sometimes be restricted or removed entirely depending on the property and location.
When Is Planning Permission Usually Required?
Planning permission is more likely to be required when:
The extension exceeds permitted development size limits
The property is located within a conservation area
The home is a flat or maisonette
Previous extensions have already used permitted development allowances
The design significantly alters the appearance of the property
The proposal affects neighbouring properties or boundaries
In many cases across Worthing and West Sussex, rear extensions can still fall within permitted development limits, although it is always important to assess each property individually before progressing too far.
How Large Can a Rear Extension Be Under Permitted Development?
This depends on the type of property.
As a very general guide:
Detached houses can often extend further than semi-detached or terraced properties
Height restrictions apply
Materials should generally appear similar to the existing property
Side-facing windows often require obscure glazing
Certain proximity rules to boundaries also apply
Because every property is different, it’s always sensible to review the specific site conditions and planning history before assuming permitted development applies.
What About Conservation Areas in Worthing?
Some parts of Worthing and surrounding areas include conservation areas where additional planning restrictions may apply.
Properties within conservation areas often require a more sensitive design approach, and certain permitted development rights may be more limited.
This does not necessarily prevent extensions or alterations, but it can influence the scale, appearance and planning route for the project.
Do I Still Need Drawings If Planning Permission Isn’t Required?
Usually, yes.
Even where projects fall under permitted development, accurate drawings are still incredibly important.
Measured surveys, existing drawings and proposed plans help:
Confirm compliance with permitted development rules
Communicate proposals clearly
Support builders and structural engineers
Prepare Building Regulations drawings later in the process
Many homeowners also choose to apply for a Lawful Development Certificate to formally confirm the work is permitted, which requires drawings and supporting information.
What Happens After Planning Permission?
Whether a project proceeds under permitted development or through a full planning application, most residential projects will still require Building Regulations drawings before construction begins.
Planning drawings focus on the overall design and appearance of the proposal, whereas Building Regulations drawings provide the technical construction information required for approval and construction.
This often includes:
Structural information
Insulation and thermal details
Construction sections
Drainage considerations
Compliance with current Building Regulations
Starting the Process
One of the biggest challenges for homeowners is simply knowing where to begin.
The early stages of a project can often feel overwhelming when trying to understand planning permission, permitted development, technical drawings and construction requirements all at once.
At Downland Studio, projects are approached collaboratively and practically — helping homeowners navigate the process clearly and confidently from the outset.
If you’re considering a rear extension in Worthing or across West Sussex and would simply like some honest advice before getting started, feel free to get in touch for an informal conversation.