Planning Permission Explained: What Homeowners Need to Know Before Starting an Extension

For many homeowners, planning permission is the aspect of a building project that causes the most uncertainty. Questions about what is allowed, how long the process takes and whether permission is even required can make it difficult to know where to begin.

While every project is unique, understanding the basics of planning permission early can save time, reduce stress and help your project move forward more smoothly.

At Karenna Wilford Architects, we guide clients through the planning process from the earliest stages, helping to turn ideas into achievable proposals.

Early conversations matter — reviewing plans together before a project begins.

1. What Is Planning Permission?

Planning permission is the formal approval required from a local planning authority before certain building works can take place. The purpose is to ensure that developments are appropriate for their surroundings and do not negatively impact neighbouring properties, local character or the environment.

Not every extension requires planning permission, but understanding whether your project falls within planning regulations is an important first step.

Clear, well-prepared drawings form the backbone of a strong planning application.

2. Permitted Development vs Planning Permission

Many homeowners are surprised to learn that some extensions can be built under Permitted Development Rights.

Permitted development allows certain works to proceed without submitting a full planning application, provided strict criteria relating to size, height, location and design are met.

However, these rights can be restricted or removed in certain circumstances, including:

• Listed buildings

• Conservation areas

• Areas of Outstanding Natural Beauty and National Landscapes

• Properties with previous planning restrictions

Before making assumptions, it is always advisable to seek professional guidance.

A rear extension by Karenna Wilford Architects — the kind of project that may fall under permitted development.

3. What Local Authorities Consider

When assessing a planning application, local authorities review a range of factors.

These typically include:

• Impact on neighbouring properties

• Privacy and overlooking

• Access to daylight and sunlight

• Scale and appearance

• Relationship to the surrounding area

• Environmental considerations

A well-designed proposal addresses these issues from the outset, making it easier for planning officers to support the application.

Elevation and site drawings give planning officers the detail they need to assess a proposal.

4. Common Reasons Applications Are Refused

Many planning refusals are avoidable.

Applications are often rejected because they fail to consider local planning policies or because the proposed design has a significant impact on neighbouring homes.

Common issues include:

• Excessive scale or height

• Poor relationship to the existing property

• Loss of privacy

• Overshadowing adjacent buildings

• Insufficient supporting information

Working with an experienced architect can help identify potential concerns before an application is submitted.

Considered floor plans help anticipate and resolve planning concerns before submission.

5. Why Good Design Improves Planning Success

Planning permission is not simply about meeting regulations. Good design plays a significant role in achieving approval.

Extensions that respond sensitively to the existing house, respect neighbouring properties and enhance the overall setting are often viewed more positively by planning authorities.

This is why architectural input is valuable from the earliest stages. A carefully considered design can improve both the quality of the finished home and the likelihood of planning success.

A contemporary home by Karenna Wilford Architects, designed to sit comfortably within its surroundings.

6. How Long Does the Process Take?

Planning timelines vary depending on the project and local authority.

A standard householder planning application is typically determined within eight weeks, although more complex projects may take longer.

It is also important to allow time for:

• Initial surveys

• Design development

• Preparation of drawings

• Application submission

• Potential revisions

Building these timescales into your project plan helps avoid unrealistic expectations and unnecessary frustration.

From drawings to build — every stage of an extension needs time built into the plan.

Preparation Leads to Better Outcomes

Planning permission does not have to be overwhelming.

With the right advice, a clear understanding of the process and a well-developed design, homeowners can navigate planning requirements with confidence.

Whether your project requires full planning permission or falls under permitted development rights, early professional guidance can help avoid delays and improve outcomes. At Karenna Wilford Architects, we support clients through every stage of the planning journey, helping transform ideas into successful, approved projects.

Thinking About an Extension?

If you are considering extending your home and would like expert advice on planning permission, permitted development rights or design options, we would be delighted to help.

Contact Karenna Wilford Architects today to arrange an initial consultation and take the first step towards bringing your project to life.

→ Get in touch to discuss your project today