Contact Us

Permitted Development vs Planning Permission

Planning Permission

1. Introduction

Let me guess, you need that little bit of extra space in your house and have been watching old episodes of Grand Designs for inspiration! I agree that’s one of the best places to start. But what is the best planning route to deliver your dreams design…permitted development or planning permission?

That’s a question we’re often asked. Fortunately we have an expert team of architects and planning permission experts who have prepared this ultimate guide to answer all your questions.

As there are so many different types of extension to choose from, we tell you if the permitted development or planning permission route is best for each.

2. Planning permission explained

Planning permission is a way of asking your local authority if your new extension plans comply with their planning policies.

There are three main types of projects that require planning permission:

  • Building an extension or a loft conversion
  • Building something entirely new – like a house
  • Change of use – turning your house into flats

Your local planning authority will have different policies for different types of extensions.

But…there are also certain types of extensions you can build without needing to apply for planning permission. This involves something known as Permitted Development. This means that you might be able to avoid lots of planning red tape and begin building sooner. Let’s explain.

3. Permitted Development explained

If you own a house, the chances are that you already benefit from certain ‘Permitted Development Rights’. This means that your local planning authority may allow you to build certain types of extensions without the need to apply for planning permission. This can bring with it several advantages:

Advantages of Permitted Development

Speed up the planning process: Permitted Development can bypass the entire planning permission process which saves a lot of time (and money).

Avoids red tape: It also circumnavigates quite a bit of red tape associated with planning policies, making it easier to renovate or extend your home.

So you can immediately see why Permitted Development is a good thing.  But what about disadvantages?

Disadvantages of Permitted Development

Complicated legislation:  Although there are no planning policies to consider, there is legislation which your new extension will need to meet. The legislation is called the ‘General Permitted Development Order’. It’s quite a long and technical document, which can be difficult to digest.

No wiggle room: Permitted Development legislation is black and white. This means your plans either meet the requirements or they don’t. A little brutal we know, which is why you can’t afford to get it wrong! Planning policies on the other hand are more subjective and can be applied or interpreted in lots of different ways, which could be good if you have grand ideas for your new extensions.

4. Do I have Permitted Development Rights?

This is often the first question we are asked. Before jumping down a Permitted Development Google wormhole, you should be aware that some properties don’t have access to Permitted Development Rights. To clarify, if your project falls into any of the categories below, your extension will require planning permission:

Flats: If you live in a flat or maisonette you will not benefit from Permitted Development and will need to apply for planning permission if thinking of extending your home.

Restricted areas: If you live in one of the following areas, your Permitted Development rights may be restricted: Conservation area, national park, area of outstanding natural beauty, a world heritage site or the Norfolk or Suffolk Broads.

Permitted Development rights are withdrawn: There are specific instances where your Permitted Development Rights may have been withdrawn. If you live in a new house, your rights might have been withdrawn through a condition attached to a previous planning approval. Local planning authorities can also introduce what’s called an ‘Article 4 Direction’. These can remove specific Permitted Development rights in certain areas.

5. Planning Permission or Permitted Development: how to choose between them

This is a tough one, but we can guide you to the decision that benefits your ideas the most. It really does depend on your specific site circumstances and the type of extension you would like. There are quite a few differences between planning permission and permitted development. To help you select the best route, we have highlighted some of the most common household extension projects below. Because most of us want to add the largest amount of space possible, our in-house planners have picked the option which usually creates the most space.

Loft conversion – Planning permission or Permitted Development?

Answer: Permitted Development

Why? When planning a loft conversion through Permitted Development, there is only one main restriction concerning the size. You’re allowed to add 50 cubic metres of space. We know that can be hard to visualise but the majority of us have seen a neighbour’s loft conversion. They often involve a gabled wall and a big rear dormer window. In most cases that adds up to 50 cubic metres of space. Big enough for a big master bedroom and that roll top bath you have always wanted.

But under planning permission, most local planning policies will only allow a very small dormer window, which is only half the depth and width of the roof space and no gable. This is why it’s always a good idea to go down the Permitted Development route when it comes to loft conversions as you end up with a much bigger space.

3D model of a permitted development dormer loft conversion surrounded by trees

Rear extension– Planning permission or Permitted Development?

Answer: Planning Permission and Permitted Development!

This is an unusual one as both can apply. 

When it comes to rear extensions, most local planning departments will have a document called ‘Residential Design Guidance’. It gives generic information to homeowners about the acceptable size of certain types of extensions. As a rule of thumb, here are the approximate depths of single-storey rear extensions most local authorities would deem acceptable.

Terraced house:                     3m deep single-storey rear extension

Semi-detached House:          3.5m deep single-storey rear extension

Detached house:                    4m deep single-storey rear extension

When it comes to Permitted Development legislation, the rules are quite similar to the above. The main difference is that semi-detached houses under Permitted Development can only have a 3m deep single-storey rear extension. So, in this case, going down either route will yield similar-sized extensions in the majority of projects.

3D model of a modern single storey rear extension surrounded by trees

Larger rear extension – Planning permission or Permitted Development?

Answer: Permitted Development

Good news! Going down the Permitted Development route provides a way to get a slightly larger single-storey rear extension, giving you more room to play around with. If you live in a terraced or semi-detached house, you can build up to 6m deep and if you own a detached house, you can build an 8m deep extension. The only way this can be achieved is through the Permitted Development route. This is commonly known as ‘Prior Approval’ or the ‘Larger Home Extension Scheme’. There are a few hoops to jump through before you can start building. Because planning policies rarely allow for 6m or 8m deep rear extensions, in this case, Permitted Development is the best option if you want something larger.

3D model of a modern 6m deep single storey rear extension obtained through permitted development

Side Extension– Planning permission or Permitted Development?

Answer: Planning permission and Permitted Development

Similar to rear extensions, most local planning policies for side extensions are similar to Permitted Development legislation. If you follow these basic rules, you will be complying with the Permitted Development legislation as well as most local planning policies.

Side extension width:                         Half the width of the original house

Side extension depth:                        Should not extend beyond the front or rear of your house

Side extension height:                       Approx. 3m

3D model of a modern single storey side extension

Wraparound extensions– Planning permission or Permitted Development?

Answer: Planning permission

Why? With this type of extension, Permitted Development, unfortunately, does not apply. If you’re like me, you would like the biggest ground floor living space possible. A huge open-plan kitchen and living room. A utility room to hide your washing. Maybe a little home office to get away from noisy kids. You can have all of this with a wraparound extension.

Unfortunately, this can’t be achieved through Permitted Development. The only way it can be done is through planning permission. Please bear in mind that how your local authority assesses your application will depend on your specific site circumstances and their planning policies. All local authorities are different so it’s always worth discussing your ideas with your architect or a planning consultant.

3D model of a wrap-around single storey house extension obtained through planning permission rather than permitted development

Two-storey rear extension – Planning permission or Permitted Development?

Answer: Planning permission and Permitted Development

Why? You can technically build two-storey rear extensions through either planning permission or Permitted Development. The main limiting factor when it comes to Permitted Development is that they cannot be deeper than 3m and cannot be within 2m of a boundary. If you don’t meet these requirements, you would need to apply for planning permission. Bear in mind that planning policies can also be quite restrictive when it comes to two-storey extensions due to their height and potential impact to your neighbours’ gardens.

3D model of a two storey rear extension obtained via the planning permission route

Garden room – Planning permission or Permitted Development?

Answer: Permitted Development

Why? You can build a garden room extension through either Permitted Development or planning permission. As most of us would like as much space as possible, this is more easily achieved through Permitted Development. This is because the main limit on the size of a new garden room extension is that it shouldn’t be bigger than 50% of your garden. Even if you have an average size garden, a home office which is half as big would be huge! That’s why in most cases you will achieve more space through Permitted Development.

3D model of a home office extension in the garden obtained through the permitted development route

Garage conversion – Permitted Development or planning permission?

Answer: Permitted Development

Why? In most cases, you can obtain planning permission quite easily for a garage conversion, but planning permission requires preparing a full set of plans and the associated architect’s fees, which can all add up. This process also takes a lot longer. As you can achieve the same thing through Permitted Development it makes sense to cut out some of the red tape and go down this route. You get the garage conversion you want with less time and money involved – so you can spend more time thinking about what you’re going to do with your brand new room!

3D model of a garage conversion

6. New changes to Permitted Development

If we look at the most recent change to Permitted Development legislation, you could potentially add one or even two additional storeys to your house – without the need for planning permission!

There are however a few limitations that you should consider first:

The number of additional storeys: If you own a bungalow, you can add one additional storey. If you own a two-storey terraced or semi-detached house, you can add up to two storeys.

Height: The house cannot exceed 18 metres in total height. Each added storey cannot add more than 3.5 metres to the total height. If not detached (e.g. terrace or semi) the total height cannot be more than 3.5 metres higher than the next highest building that the house is attached to, adjoins, or is in the same row as.

Location: The additional storeys must be constructed on the principal part of the house.

Structural considerations: If your engineer says that the existing structure needs to be reinforced to take the weight of additional floors, those construction works must be made to the inside of your house rather than the outside.

Materials: The materials used must be of a similar appearance to those used in the construction of the exterior of the current house.

Windows: These must not be placed in any wall or roof slope forming a side elevation of the house.

7. The planning process explained

For those of you who haven’t been through the planning process before it can seem a little daunting, but it’s a pretty simple process once you know all the steps involved. There will be a few simple stages involved in your design and planning journey:

1. Inspiration

This is the most fun part! When we need ideas we take to Pinterest, Google, Instagram and even TikTok. Or make a big pot of coffee (grab a biscuit) and settle down to watch a few episodes of Grand Designs. Find as many examples as possible of all the things you love. That might be an extension design, stunning colour schemes, jaw-dropping tiles or a beautiful pendant light. Create a mood board where you bring all of these things together to show your designer or architect.

2. Find an architect

Whether you’re extending out or extending up, an architect will be an important part of your project. They will first take a look at your ideas and inspirational mood boards, so they know exactly what you’re looking for. They will then use all their creativity and previous experience to create something fantastic.

3. Design Stage – bringing your ideas to life

Sit down and discuss your ideas with your architect. This way, they will gain a very good understanding of the vision you have for your extension. To begin with, they will survey your house so they can prepare a set of existing plans i.e. how the property looks now. They will then use their creativity to design your incredible new living space and prepare a proposed set of plans. Once you have your dream plans in hand and agreed, it’s time to get in touch with the planning department of your local authority. Your architect will take care of this on your behalf.

4. Application – Permitted Development or Planning?

At the start of the process, your architect would have advised on which planning route would be best for your project. If it’s the planning permission route, your architect would submit a householder planning application. If your extension is Permitted Development, they will apply for a ‘certificate of lawful development’.

5. Local Authority review

Once your application has been submitted all the hard work is over and you sit back and relax. However, there are still a few more smaller hurdles to get over. Your local planning department will first validate your application and the details will be published online. They will then usually take 8 weeks to issue a decision. In some cases, they may ask for a few tweaks to the drawings having reviewed your plans. Make sure your architect gets any changes made quickly so as not to cause delays.

6. Pop the champagne

Congratulations! You’ve completed each stage and by now, your application will have been approved. So that’s the planning stage over with. Phew. But there is still the building regulations stage to get through.

8. Steps after planning permission?

Most projects – no matter how elaborate your plans are – will fall neatly into one of three main categories here:

Ready to build

If you’re like me, you will want to get into your incredible new extension ASAP. To do this, there are a few steps to complete:

  1. Detailed drawings – your architect will prepare a set of drawings showing construction details like foundations, insulation, or supporting steel.
  2. Engineer – you will also need an engineer to prepare a set of structural calculations and structural drawings.
  3. Party wall agreement – if you’re building near a shared wall with your neighbour you might need a party wall agreement.
  4. Submit your application to building control – Once the architect’s and engineer’s plans are ready, you can submit your application for building control approval. They will check your plans to see if they comply with the relevant British Standards. A building inspector will also arrange to meet with your builder on site to ensure that your construction process reaches particular milestones.
  5. Find a builder – There are a few options here. There are plenty of useful review sites available online so you can check the work and feedback on your builder. Alternatively, you can ask your architect or find out which builder friends and family have used. Word-of-mouth is a great option, as you will get an honest opinion of your intended builder’s work.

Not quite ready to start building?

There are lots of instances where homeowners might not want to dive straight into the construction process. Perhaps build costs have increased, or you would rather start the construction process in the summer when the weather is better. Perhaps after all the excitement of the planning process, you just need to catch your breath.

Planning permission: if you have obtained planning permission but don’t want to start the works yet you have two options:

1. First you could implement your planning permission. This means carrying out some sort of building work such as digging foundations. Once started you can finish the work whenever you wish – completely at your leisure!

2. If you’re wondering how long planning permission lasts for? The answer is usually 3 years from the date permission was granted. If you haven’t started by that expiry date you would need to reapply for planning permission, as it cannot be renewed.

Permitted Development: If you went down the Permitted Development route there is good news! There is no time limit by which time you need to start building works. Don’t leave it too long just in case the legislation changes. Plan ahead, get some dates in your calendar and look forward to the whole exciting project getting underway.

Your application was refused

This is the last thing anyone wants but if your planning application is refused all is not lost. You still have a few options that your architect or builder can take care of for you:

Appeal the decision: If you don’t agree with the local authority’s decision you have the right to appeal. The good news is the process is free. Your application will be assessed by the Planning Inspectorate, which is a completely independent body and not linked to your local authority. For most householder or Permitted Development projects, it takes between 3 – 4 months for your appeal to be determined.

Revise and resubmit: Appealing should always be a last resort. If your application has been refused your local planning authority will have prepared a ‘delegated report’. This is a comprehensive assessment written by the planning officer, explaining their specific concerns in detail. If these can be addressed, you can revise your plans and resubmit. The great news is that if you do this within 12 months you don’t need to pay the application fee again.

9. Conclusion: The Planning system isn’t that difficult to navigate

Getting to grips with complex planning policies and Permitted Development legislation can be a challenge, but it isn’t that difficult to navigate with us by your side. At Adara, half of our team are former local authority planners! This means we have a very good understanding of all the relevant policies and how the planning system works in practice. We’ve been on the other side of the fence so know exactly how planning officers work and think.

If you have any planning questions or have some design ideas you’d like to discuss, feel free to call a member of our friendly team at any time. We’re always here to help!

Turn your dream home
into a reality today

Book a free consultation with one of our friendly, expert architects to discuss your ideas.

See also

Related articles

Like the sound of us but want to know more?

Give one of our cool, creative architects a call to chat all things design and planning