London Planning Permission Questions Answered: Director Q&A

Do I need planning permission for my extension or renovation

First, what do we mean when we say ‘Planning Permission’? Often it’s collapsed with meaning ‘any sort of application for permission to the Council planning department’.

Whether you need planning permission or not will depend on whether the extension proposal’s size, nature and location all meet Permitted Development rules or not. If they do, no permission is ‘needed’. If they do not meet the rules, then permission may be needed. Some extensions fall under Permitted Development and don’t need planning permission. Others, particularly in conservation areas or on listed buildings, need a more involved application and process.

Planning Permission or Certificate of Lawfulness – What is the difference?

Planning Permission is distinct from a Certificate of Lawfulness. The former asks the council to judge a proposal against the planning policy, while the latter asks the council to check if the proposal meets the lawful definitions pre-granted by Permitted Development. They sometimes clash in unexpected, interesting ways and a good architect knows how to strategise on your behalf to pick the best path.

One thing to think about. The word ‘need’ can miss the point of ‘might you want Planning Permission even if you don’t need it?’. A Certificate of Lawfulness is, in most homeowner cases a voluntary confirmation that your proposals-as-drawn meet the Permitted Development rules. So, you may not need that but it could help you sleep easier for years and aid you sell the home down the line, with that added evidence of legitimacy. So really the question here may be, what is the value of peace of mind? 

How long does planning permission take?

Officially, councils have eight weeks to decide on a standard application, thirteen for anything larger or more complex. In practice, it often takes longer, and we’d rather tell you that upfront than have you caught out by it.

Delays usually come from requests for more information, objections that need addressing, or a backlog at the local authority. Frustratingly, they all differ. We build realistic timeframes into your project plan from the start, based on how that particular council tends to operate. Where we can move things along, whether that’s pre-application advice or getting ahead of likely questions, we do. It’s also worth noting the changes that came into effect on 1 April 2026. The short version is that the appeals process places much greater emphasis on getting planning applications right from the start. (See more in our blog New Planning Appeal Rules 2026: Why Your First Submission Now Matters More Than Ever. )

What happens if my neighbours object to my application?

An objection doesn’t automatically mean refusal. Planning officers weigh objections against planning policy, not personal preference, so a complaint about the colour of your brick or a general dislike of change carries very little weight. Objections about genuine planning matters, loss of light, overlooking, or scale, carry more.

From our perspective, we think about how a design will be seen by neighbours long before it reaches the council. Where useful, we’ll suggest speaking to them directly before you submit. A quick conversation early on solves far more than a heated one after an objection’s already been filed. If an objection does come in, we’ll help you understand whether it holds planning weight and how best to respond. (See our guide on telling your neighbours about your plans in our blog Extending your home? Here’s how to tell neighbours about building work.)

What happens if my planning permission is refused? Can I appeal or resubmit?

Yes, you have options, and a refusal is rarely the end of the road. You can appeal the decision, submit a revised application addressing the reasons for refusal, or in some cases go back with a completely different approach to the same brief.

We treat a refusal as information rather than a dead end. The reasons given tell us exactly what the council needs to see differently, and in our experience, a well-considered resubmission has a strong chance of success. We’ve taken on projects with a history of failed applications before ours and turned them around, so if you’re in that position already, it’s a conversation worth having.

Do you need a party wall agreement, and is that separate from planning permission?

Yes, and yes. A party wall agreement covers work that affects a wall, boundary or structure shared with a neighbour, things like loft conversions, new foundations, or digging near a shared wall. It sits entirely outside the planning system, under the Party Wall Act, and it’s easy to miss if nobody’s flagged it early. (See our Party Wall guide Party Wall Agreements: 10 Questions London Homeowners Ask Before Building Work Begins.)

We check whether your project needs one as part of our early planning. That way it’s dealt with in good time rather than becoming a last minute scramble before construction starts. If you do need a Party Wall Agreement, we’ll explain what’s involved, who needs to be appointed, and how it fits into your overall project timeline.

We handle planning applications as part of our service and bring local knowledge of how individual London boroughs tend to approach these decisions. If you want to understand the basics before you speak to us, there is some great information here Permitted Development Guide covers what you can build without an application, and what you can’t.