Do You Need Planning Permission for a Home Extension in North London?

If you are thinking about extending your home in North London or Hertfordshire, "do I need planning permission?" is usually the first question, and the honest answer is "it depends on your property". This guide explains how to work out where you stand before you spend money on drawings.

What permitted development actually means

Permitted development (PD) rights let homeowners carry out certain building work without submitting a full planning application, provided the work stays within set limits. They are national rules, but councils can remove or restrict them in particular areas, which is why two similar houses on neighbouring streets can be treated differently.

PD is not a loophole and it is not automatic. It only applies if the house is a single dwelling (not a flat or maisonette), the rights have not been removed, and the design keeps within the limits.

The main limits for a single-storey rear extension

As a rule of thumb, for a single-storey rear extension:

• it can extend up to 3 metres beyond the original rear wall of a terraced or semi-detached house, or 4 metres for a detached house
• a larger extension of up to 6 metres (8 metres for detached) may be possible through the prior approval route, where neighbours are consulted
• the height is capped, with lower limits for eaves close to a boundary
• extensions and outbuildings together cannot cover more than half of the land around the original house
• materials should be similar in appearance to the existing house

These figures are a starting point, not a guarantee. Always confirm the current rules with your local council or a qualified professional before you rely on them.

When you will need full planning permission

You are likely to need a full planning application if:

• you live in a flat or maisonette
• the property is listed, or sits in a conservation area with tighter controls (North London has many, and so does Hertfordshire)
• an Article 4 direction has removed PD rights in your street
• the design is two storeys, or wraps to the front or side beyond PD limits
• the house has already been extended or converted in a way that uses up the allowance
• the original planning permission for the house removed PD rights

A householder planning application in England is normally decided within about eight weeks, so it is worth building that into your timeline.

Get certainty with a Lawful Development Certificate

If you believe your plans fall under PD, you can apply to the council for a Lawful Development Certificate. It is optional, but it gives you written confirmation that the work is lawful, which is valuable when you come to sell.

Building Regulations are separate

Even when no planning permission is needed, an extension almost always needs Building Regulations approval. This covers structure and foundations, insulation, fire safety, drainage, ventilation and electrics. A Building Control officer inspects at key stages and issues a completion certificate at the end. Keep it safe: buyers' solicitors will ask for it.

Do not forget your neighbours

The Party Wall etc. Act 1996 requires you to serve notice on neighbours if you build on or astride a shared boundary, work on a shared wall, or excavate close to their foundations (generally within 3 metres, and in some cases 6). It is a separate process from planning, and skipping it can stop a project in its tracks.

How we help

At White Buffalo Bespoke we advise you on this early, before the design is fixed, and handle the application if planning permission is required. If you would like a second opinion on your own house, get in touch for a free, no-obligation visit. You can also read how we approach home extensions or see our answer in the FAQs.