Q: Do you need planning permission for a side return extension? Very possibly not!

This is such a common project in UK towns and cities, for good reason. Many Victorian terraces have this strip of garden space that is so often dark and under-used. Claiming this space back internally can transform a kitchen or living space, without affecting the enjoyment of your garden. It’s even more of an attractive proposition if you discover that you don’t need planning permission for a side return extension as it may well fall under permitted development guidelines.

What is permitted development? Permitted development rights are a national grant of planning permission which allow certain works to be carried out without having to make a planning application. To find out if permitted development rights apply to your project, just ask yourself the following questions:

Find your perfect design pro within minutes…

Here at Design for Me, we’ve helped thousands of homeowners all over the UK to find the best architect or designer for their project.

✓ Get matched within minutes and see who’s interested.
✓ Get no obligation quotes.
✓ It’s completely free.

Do you own the whole house?

If the answer is no, permitted development rights will not apply to you and you will need to apply for full planning permission.

Yes? Tick! Move on…


Do you live in a Conservation Area?

Or other ‘protected’ areas, including:

  • National Parks
  • Areas of Outstanding Natural Beauty
  • the Norfolk or Suffolk Broads
  • a World Heritage Site

If the answer is ‘yes’, you may not be able to take advantage of permitted development rights or they might be restricted. In particular, your permitted development rights might have been removed if there is an ‘Article 4’ direction for your property. Speak to your architect about this, or consult your local council directly.


Have there been any previous extensions to the ‘original house’?

The ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before this time).

If so, it’s likely that this will eat up some or all of your permitted development allowance.


Size limits – will it extend beyond three metres?

Good news! In the last few years, the permitted development rules were relaxed, allowing you to build an extension without planning permission of up to six metres out (or eight metres if your house is detached). They may well extend this deadline, but currently, you need to complete your project by May 2019. To meet permitted development rules it will also need to: Update 2020: Great news – the deadline no longer applies and the ‘lager home extension scheme’ has been made permanent!

  • be single storey.
  • not exceed 50% of the total area of land around the ‘original house’ (see above). Sheds and other outbuildings must be included when calculating the above 50% limit.
  • be no more than 4m high.
  • be no wider than half the width of the original house. 
  • If the extension is within two metres of a boundary (which a side return extension usually is), maximum eaves height should be no higher than three metres to be permitted development.

This point is important though: if you plan to extend by more than three metres (i.e. the length of the side return), it will be subject to a prior approval process called the Neighbour Consultation Scheme. So, before you start work you will need to notify the council who will then consult with your adjoining neighbours. The council will take any concerns or objections on board in relation to the impact of your extension on neighbouring properties.

A common restriction or condition as a result of this process is the need to limit the height of the wall on or next to the boundary wall, to reduce the impact of loss of light. Permitted development rules allow boundary walls and fences to be erected up to two metres, so it may be permissible that the extension is two metres high at the boundary wall, with the roof sloping up to the existing house, similar to the example pictured below.


planning permission for a side return extension

Side return extension by Zoe, an architect on Design for Me. See her profile and shortlist her for your project here



Should you get a Certificate of Lawful Development?

This may come in useful when you come to sell your property, to show the buyer or buyer’s mortgage lender that your extension without planning permission was legal. This is a useful seal-of-approval document, when you are confident that your proposals meet permitted development guidelines. However, if you are unsure, this application may not be the best route to finding out! The process is very black and white, and there is usually very little dialogue between you and the planning authority during the application process, unlike a traditional planning application. So you might apply, and be hit with a big fat ‘no’, wasting time and money. A better route is to seek pre-planning advice from your local planning authority and find a good architect who can help you navigate the maze of planning, and other permissions.


Some other articles you may find useful before starting your infill extension: 


Can I build an extension without permission? 

It’s not only planning permission for a side return extension that you’ll need. Find out about party wall awards with your neighbours. 

How much does a side return extension cost?

A simple guide to calculating your extension cost.

Side return extension ideas

Get some design inspiration for your side return extension!

Should I pay for planning pre-application advice?


Finding your side return extension architect

It’s important for you to have a basic understanding of whether you need permission for a side return extension, but the most critical thing is that you find the right architect to guide you through these legal requirements alongside the design decision-making process.

Here at Design for Me, we can match you with the perfect architect for your side return extension. Choose up to three interested design professionals for an initial consultation. And it’s all completely free!

  • Quickly see who’s interested in your job.
  • Create a shortlist.
  • Invite up to three for a no-obligation consultation.


Emily  Design for Me


Find your perfect design pro within minutes…

Here at Design for Me we match you with the right design professional, from thousands all over the UK. Get quotes & arrange up to three no obligation consultations. And it’s all completely free! Find out more here or get started below…



Leave a Reply

  • (will not be published)