What is Prior Approval?

A Simple Introduction from Our Experience

At London Extend, many of our clients come to us with a bold vision: a truly transformative, full-width rear extension that dramatically reshapes their ground floor living space. You may have heard that it's possible to build a single-storey rear extension up to six, or even eight, metres deep under Permitted Development rights.

This is true, and it presents a fantastic opportunity. However, it is not as simple as just building it. These larger extensions fall under a special process known as Prior Approval.

Understanding this process is critical. It is a formal procedure with strict rules, timelines, and a unique focus on your neighbours. It sits in a middle ground between a simple Lawful Development Certificate (LDC) and a full planning application. As a firm that manages these applications every week, we want to give you a clear, practical guide to how it works and how to approach it for a successful outcome.

The Concept in Plain English

So, what exactly is Prior Approval in this context?

Prior Approval is a specific requirement under the Larger Home Extension Scheme. It applies only to single-storey rear extensions of a certain size:

• For a terraced or semi-detached house, it applies to extensions projecting between 3 and 6 metres from the original rear wall.

• For a detached house, it applies to extensions projecting between 4 and 8 metres from the original rear wall.

(Extensions smaller than these thresholds do not require Prior Approval, though we would always advise securing a Lawful Development Certificate for them.)

The crucial thing to understand is that Prior Approval is not planning permission. When we submit a Prior Approval notification, the Local Planning Authority (LPA) is not asked to judge the quality of the design, the choice of materials, or whether they 'like' the extension.

Their assessment is limited by law to a single question: what is the impact on the amenity of any adjoining premises? In simple terms, they are only allowed to consider how your new, larger extension will affect your immediate neighbours, specifically regarding issues like a potential loss of light or outlook.

The Official Process Step-by-Step

Navigating the Prior Approval process involves a strict, time-bound sequence of events as set out in planning law.

1. Submission of Notification: We begin by formally notifying the LPA that you intend to build a larger extension under these specific rights. This isn't a full planning application; it's a defined set of information including a description of the work, accurate plans, the addresses of your adjoining neighbours, and the relevant fee.

2. The Neighbour Consultation Scheme: This is the heart of the process. Once our notification is validated, the LPA will formally write to the owners or occupiers of all adjoining properties (the homes that share a boundary with you). They will provide details of your proposal and give your neighbours a statutory period of at least 21 days to raise any objections.

3. Assessment Scenario A: No Objections Received. If the 21-day consultation period passes and no neighbours have objected, the process is straightforward. The LPA will issue a notice stating that Prior Approval is not required, and you are free to proceed with the build (once any other legal checks, like an LDC, are complete).

4. Assessment Scenario B: Objections Are Received. If an adjoining neighbour objects, the LPA's role activates. They must now assess the planning merits of the objection and decide if the impact on that neighbour's amenity is acceptable. They will consider the size, scale, and position of your extension relative to the neighbouring property. They will then either grant Prior Approval (if they find the impact acceptable) or refuse it (if they find the impact is unacceptable).

5. The 42-Day Clock: The entire process runs on a strict statutory clock. The LPA has 42 days (6 weeks) from the date your notification was validated to issue their decision. Critically, if you do not hear anything from the LPA within this 42-day period, you gain a 'deemed consent'. This means you can legally proceed with the development.

6. Notification of Completion: A final, small piece of administration. Once the extension is built, you must write to the LPA to inform them of the completion date.

How This Impacts Your Project in London

Given that much of London's housing stock consists of terraced and semi-detached properties, the Prior Approval scheme for extensions between 3 and 6 metres is incredibly relevant. The close proximity of homes makes the Neighbour Consultation Scheme a very real factor.

In our experience, the single most effective way to ensure a smooth Prior Approval process happens before we even submit the paperwork. We strongly advise all our clients to speak to their neighbours personally. A friendly conversation, showing them the plans and explaining the project, is far more effective than them receiving a cold, formal letter from the council out of the blue. This proactive engagement can pre-empt objections and foster goodwill.

Furthermore, we always recommend that a Prior Approval application is run in parallel with an application for a Lawful Development Certificate (LDC). The Prior Approval notice only confirms that the impact on neighbours is acceptable. It does not legally confirm that your extension complies with all the other Permitted Development rules, such as height limits, materials, or site coverage. Only a full LDC gives you that complete, watertight legal protection.

Common Pitfalls We've Seen

This is a technical process, and mistakes can be costly. We help our clients avoid these common errors:

• Inaccurate Measurements: Submitting a plan for a 6.1-metre extension under this scheme will lead to an instant refusal. The dimensions are absolute, and millimetres matter.

• Starting Work Prematurely: Beginning construction before the 42-day period has expired or before you have received a formal notice is unlawful and can lead to enforcement action.

• Ignoring Objections: Assuming a neighbour's objection has no merit. If an objection is raised, the LPA must assess it, so it's vital that the initial design has already considered potential impacts.

• Relying Only on Prior Approval: Completing a £100k+ extension with only a Prior Approval notice is risky. Without an LDC, you leave yourself open to legal challenges on other aspects of the design when you come to sell the property.

Our Concluding Advice

The Larger Home Extension Scheme is an excellent route for achieving a substantial, life-changing extension without the full subjectivity and expense of a planning application. However, it is not an informal process.

It is a legal mechanism governed by strict procedures and timelines, with a specific focus on the amenity of your neighbours. Success requires precise drawings, a thorough understanding of the rules, and proactive, professional management. By treating Prior Approval with the seriousness it deserves, you can unlock the full potential of your home.