Permitted Development vs. Full Planning

A Simple Introduction from Our Experience

Stop guessing. Start building. As a builder, your reputation is built on delivering quality projects on time and on budget. The single biggest variable that can derail a project before a single brick is laid is the planning process. Misunderstanding the line between Permitted Development (PD) and what requires a Full Planning Application can lead to client disputes, expensive delays, and in the worst-case scenario, an enforcement notice from the council demanding you tear down your hard work.

At London Extend, we work with builders every day. We see the confusion and the risk. This guide is designed to be your definitive on-site reference. It’s not academic theory; it’s a practical, no-nonsense breakdown of the rules, born from our experience managing hundreds of applications across London. Use this to de-risk your quotes, advise your clients with authority, and get on site faster.

The Litmus Test: Is It Permitted Development?

Before you even look at the specific measurements for an extension or a loft, you must run the property through this essential Litmus Test. If the answer to any of the following questions is 'Yes', then standard Permitted Development rights likely do not apply, and you must proceed with extreme caution and almost certainly require a full planning application.

• 1. Is the property a flat or a maisonette? PD rights apply to dwellinghouses, which generally means whole houses. Flats and maisonettes have no Permitted Development rights for extensions, roof alterations, or outbuildings.

• 2. Is the property a Listed Building? If so, assume nothing is permitted. Almost any alteration, internal or external, will require specific Listed Building Consent. PD rights are effectively removed.

• 3. Is the property in a Conservation Area, a National Park, an Area of Outstanding Natural Beauty (AONB), or a World Heritage Site? These designated areas have heavily restricted PD rights. For example, in a Conservation Area, you cannot build a side extension, a two-storey rear extension, or alter the roof without full planning permission. All external cladding is also forbidden under PD.

• 4. Is the property subject to an Article 4 Direction? This is a critical point, especially in London. An Article 4 Direction is a tool used by a local council to remove specific PD rights in a defined area. This could be to prevent loft conversions of a certain type, stop homeowners from paving over front gardens, or control the changing of windows. You must check the council's website or speak to their planning department to know if an Article 4 Direction is in place.

If the project passes this initial test, you can then move on to assess the specific limitations.

The Builder's Cheat Sheet: Key Project Limitations

This table summarises the most common projects and their national Permitted Development limits. Think of this as the core rulebook. Remember, these allowances are for the original house (as it was first built or as it stood on 1 July 1948). Any previous extensions count towards these limits.

The "Prior Approval" Trap: Larger Home Extensions

This is a common and costly pitfall. Under a scheme often called the Larger Home Extension Scheme, the depth limits for single-storey rear extensions are temporarily increased: from 3m to 6m for terraced/semi-detached houses, and from 4m to 8m for detached houses.

However, this is not a free pass. It requires a process called Prior Approval.

Before any work begins, you must notify the local council with details of the proposed extension. The council then consults the adjoining neighbours. If any neighbour objects, the council will assess the impact of your proposal on the amenity of all adjoining properties. They have 42 days to make a decision. They can either approve it, or they can refuse it if they find the impact unacceptable. Building without securing this written approval is a breach of planning control. This is not just 'notifying' them; it is a formal application process with a risk of refusal.

How This Impacts Your Project in London

Working in London presents unique challenges. Tightly packed terraced housing, a high concentration of Conservation Areas, and the widespread use of Article 4 Directions mean you must be extra vigilant.

• Terraced Constraints: On a typical London terrace, the 7m rule for two-storey extensions often makes them impossible under PD. Side-return extensions often involve building on the boundary, immediately triggering the lower 3m eaves height rule for single-storey additions.

• Article 4 Hotspots: Many London boroughs have blanket Article 4 Directions removing PD rights for loft conversions, especially those visible from the street, to protect the character of their Victorian and Edwardian housing stock.

• Cumulative Impact: London properties have often been extended multiple times over the decades. It's crucial to establish what the 'original' house was, as PD allowances may have already been used up by a previous owner.

Our Concluding Advice: Get it in Writing

The single best way to eliminate all risk for you and your client is with a Lawful Development Certificate (LDC).

Think of an LDC not as an application to ask for permission, but as an application to get a legally binding decision from the council that your proposed project is lawful and does not require planning permission. You submit drawings to the council, and they provide a formal certificate confirming the project meets all PD criteria.

For a modest fee and an 8-week determination period, an LDC is the ultimate insurance policy. It gives you, your client, and any future buyer of the property absolute certainty that the work is compliant. It protects you from any future claims or enforcement action. For any project that is remotely close to the limits, we consider it an essential first step.

Unsure where your project falls? The line can be complex. Send us the property address and a quick sketch of your plans, and our expert team will provide a free, no-obligation feasibility check to determine the smartest route to getting your project approved.