Is Extension Planning Permission Vital?

An extension to your home can create the space, light and garden access you’ve hankered after. Submitting your design to the local authority for permission to make your dream of adding to your home’s floor plan come true takes time and costs money, but it is possible to avoid doing this – without breaking the rules.

extension planning permission

Image source: Architect Your Home

What are permitted development rights?

The permitted development rights mean you can build an extension to your home without the need to apply for extension planning permission. They are a time saver, allowing you to get on with your project of creating extra living space more quickly. You won’t have the uncertainty involved with applying for extension planning permission, and you won’t need to pay out for an application. Unfortunately for flat and maisonette owners, the rights only apply to houses.

do i need planning permission for a conservatory

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What sort of extension can you build?

If you live in England, under the permitted development rules you can currently build a single storey side extension that doesn’t have a width greater than half the width of the original house and a height more than 4 metres. If it’s within 2 metres of a boundary, it can’t be more than 3 metres high at the eaves.

When it comes to extending at the back of your house, a single storey rear extension can’t go higher than 4 metres. If yours is a detached house, you can generally extend at the back to a depth of 4 metres, or 3 metres if you’re in a terrace or semi. However, until May 2016, you can extend to 8 metres beyond the original rear wall for a detached, and 6 metres in an attached house, so if you want to maximise the extension size without the hassle of gaining extension planning permission, now’s the time to do it.


Overall, a single storey extension in England can’t have an eaves and ridge height higher than the existing house, and it needs to use similar materials to the existing house – so if you have an eye-catching design in mind, the permitted development route may not be for you.

It’s also important to know a little of your home’s history. Extensions together with sheds and outbuildings can’t cover more than half of the total area of land around the original house – what was first built or as it stood on 1 July 1948 if it’s older than that. You may not have extended before, but if your predecessors liked buildings more than garden space, their projects have eaten into the coverage limit.

Some two-storey extensions are possible as well, but have their own criteria. Check out all the details on the planning portal.

building an extension without planning permission

Image source: Architect Your Home

Where you live matters

The permitted development rights are not the same for England, Wales, Scotland and Northern Ireland, as each of the nations have their own guidelines. Even within a postcode, the rules might vary. If you live in a so-called designated area – including conservation areas, a national park, the Broads, or an Area of Outstanding Natural Beauty – different criteria apply.

Local authorities can also remove some of the permitted development rights with an article 4 direction, most often in a conservation area, and if this is the case you might need to apply for extension planning permission where you’d normally be able to go ahead without.

How do you know what’s permitted?

Although the permitted development rights give you freedom, what you can do in practice might not be clear to you and if you don’t get it right, an enforcement notice for developing without the required permission may be your reward. To avoid uncertainty, it’s worth contacting your local authority with your proposals – and to find out if any proposed changes to the regime could affect your plans.

You can also apply for a lawful development certificate for your extension. This does cost a little, but it will set your mind at rest that your project is lawful, and will mean you have the paperwork to show when you come to sell your house in the future, helping to speed up the sales process.

planning permission for extension

Image source: Apropos

Don’t forget the essentials

While permitted development might cut down on the paperwork when you’re extending, it doesn’t avoid it altogether. You will need to get approval under the building regulations for most extensions to cover elements such as the structural opening, the extension’s energy efficiency, the foundations, ventilation, doors and windows and so on.

The Party Wall etc Act might also affect your work, depending on the position of your extension in relation to your neighbours’ homes. For more information, check out the planning portal.

Want to add more space and value to your home by extending? Find a qualified and vetted builder with Rated People to help you unlock extra space in your property

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  1. Thank you Sarah for sharing this. This post is very informative. I plan to have a rear extension in the near future for our house. One of the things that I worry about is not getting approved right away for a planning permission. Based on what you’ve told me, I can pursue my extension design plans without the planning permission after all. I can definitely work with the specifications that you’ve mentioned for the rear extension of our house.

  2. I appreciate the information building without a planning permission. I agree that it is important to ensure that you know what is permitted and try to stick to those permissions so that you don’t have any problems later on. My mom is looking into doing an addition onto her home, I will be sure to share this information with her.

  3. Can anyone tell me if I want to build a rear extention on my bungalow without planning permission I know it can’t be more than 4mtrs out but there is a original offshot to the left rear which the extention off that is only going to be 2.3 mtrs but the otherside of the bungalow it will be 4.7mtrs is the ruling of 4 mtrs from the original offshot to the left

  4. As a first time buyer I have actually poor idea about this matter. My matter is totally different. On the process of buying house, I knew that without permission the house had been extended in the rear part and open the original wall to elevate the house in 1980. But sellers have been living in this house since 1971.
    At this movement, I can not decide what I will do.
    I have some questions. I would be grateful if some one answer or suggest me of those questions.
    1. If I buy what sorts of problem I may face?
    2. Is there any option to be legalision?
    3. What steps I can take?
    I reluctant to disclose the name of sellers because he is too old and I don’t want to let him down.

  5. my neighbor is planning to build an extension to their semi detached property or 6 metres square it will run along the centre of the properties
    cutting out my light considerably can they do it without my consent can any tell me please

    1. Hi Adrian, I’d post this a question for our tradespeople on Ask an expert. They’ll be best placed to answer this for you.

  6. Please be aware that some properties do not have permitted development rights so it’s always best to check with your local council. I would also recommend that you get outline plans drawn up and submit these to the local council to obtain a Certificate of Lawfulness to ensure your proposals comply. Hope this helps.


  7. Hi is it correct you do not need planning permission for a rear single storey extension up to 6 metres? It is a semi-detached house.

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