Permitted Development vs Planning PermissionLearn More
If you’re planning to add some much needed extra living space to your home, you may be debating whether Permitted Development is the best route to take.
There have been lots of big changes to Permitted Development in the past few years.
Our team of planning consultants thought it might be useful to create this comprehensive guide to answer all the questions you might have.
1. What is Permitted Development?
If you own a house, the chances are you benefit from ‘Permitted Development Rights’. This means that you can build certain extensions without the need to apply for Planning Permission.
Permitted Development is a great option in some cases as it bypasses local planning policies which can sometimes be applied subjectively. It also circumnavigates quite a bit of red tape, making it easier to renovate or extend your home.
Although you don’t require planning permission when using your Permitted Development Rights, there is still a set of criteria which your new extensions will need to meet. This legislation can be found within the ‘General Permitted Development Order’.
If your design falls within these requirements, then you do not need to apply for planning permission. If they fall outside of those policies, you would be required to apply for planning permission.
2. Do I have Permitted Development Rights?
Here are the main restrictions when it comes to Permitted Development:
Flats: If you live in a flat or maisonette you would not benefit from Permitted Development and would 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, a National Park, an Area of Outstanding Natural Beauty, a World Heritage Site or the Norfolk or Suffolk Broads.
Permitted Development Rights withdrawn: There are specific instances where your Permitted Development Rights may have been withdrawn. If you live in a new house, your Permitted Development Rights might have been withdrawn through a condition attached to your planning approval. Local planning authorities can also introduce what’s called an ‘Article 4 Direction’ which can remove specific Permitted Development Rights in certain areas.
3. What can I build under Permitted Development?
There are lots of different types of extensions which can be built under Permitted Development.
Below, we have highlighted the most common types of extension achievable through Permitted Development. To help you visualise what those extensions might look like, our architects have prepared some useful 3D models of each.
3.1. Loft conversion
Materials: The materials of your hip to gable or dormer window must be similar to those of the existing house.
Volume: The increase in volume (measured externally) of your loft extension must not exceed 40 cubic metres if you own a terraced house, or 50 cubic metres for semi-detached or detached houses.
Overall Height: The height of any element of your loft extension cannot exceed the height of the original roof.
Front Roof Slope: No part of the new loft extension can extend beyond the principal elevation of your house. This usually means the front of your house which faces the road, meaning most loft extensions are either to the front or side of people’s houses.
Privacy: If you would like to include some new windows, those which are side facing should be obscure glazed. If you would like them to be openable for ventilation or for a nicer view, that window must be 1.7m above the floor.
Location: Your proposed dormer window or gable should not overhang the outer face of any original walls of your house.
3.2. Rear extension
Footprint Size: Your extensions should not occupy more than 50% of the space around your house.
Height: Extensions cannot be higher than the highest part of the existing roof, or higher at the eaves than the existing eaves.
Proximity to the boundary: Where the extension comes within two metres of the boundary, the height at the eaves cannot exceed three metres.
Principal Elevation: Extensions cannot be built forward of the principal elevation (usually the front of your house) or where it fronts a highway, the ‘side elevation’.
Materials: The materials used in any exterior work must be of a similar appearance to those on the exterior of the existing house.
Depth: If you own a terraced or semi-detached house the depth of your extension cannot extend beyond the rear wall of your original house by more than 3m. If you own a detached house, that depth is increased to 4m.
6m or 8m deep extensions: extensions of this type are included with Permitted Development but require you to go down a slightly different route known and ‘Prior Approval’ which we have discussed in more detail below.
Height: Single-storey rear extensions cannot exceed four metres in height.
3.3. Side Extension
Height: The extension cannot exceed more than 4m in height.
No. of storeys: Side extensions are limited to single storeys. Two storey side extensions do not benefit from Permitted Development and would require planning permission.
Width: The width of your side extension cannot exceed more than half the width of your original house.
Conservation Areas: If you live within a Conservation Area you would require planning permission for a side extension.
3.4. Two-storey Rear Extension
Depth: Two storey rear extensions should not extend beyond the rear wall of your original house by more than 3m.
Separation: The rear wall of your two storey rear extension must be separated from your rear boundary by more than 7m.
Roof Design: The pitch of your roof should match the pitch of the existing roof.
Privacy: Any windows you choose to place in the side elevation should be obscure glazed and permanently fixed shut. If you would like part of the window to open, the openable part should be located more than 1.7m above the floor.
Conservation Area: If your house is located within a Conservation Area, extensions of more than one storey would require planning permission.
Front Garden: No outbuilding can be located forward of the principal elevation, which usually means your front garden.
Within 2m of your boundary: If your outbuilding would be positioned within 2m of your fence, the overall height would be limited to 2.5m.
Further than 2m from your boundary: If your outbuilding would be located further than 2m from the boundary, they can be slightly higher. The eaves height is still restricted to 2.5m but the overall height can be as high as 4m with a dual pitch roof and 3m high for any other roof shape.
Footprint: The total footprint of any outbuildings should not exceed more than 50% of the area around your house.
Restrictions: In National Parks, the Broads, Areas of Outstanding Natural Beauty and World Heritage Sites the maximum area to be covered by buildings, enclosures, containers and pools more than 20 metres from the house is limited to 10 square metres.
3.6. Garage conversion
Construction works: Works should be internal.
Footprint: The garage conversion should not enlarge the garage footprint.
Materials: Any external materials such as replacing a garage door with a window should match the materials of the existing house.
4. What Can’t I Build Under Permitted Development?
Above, we have summarised the criteria for the most popular types of Permitted Development extensions. If you fall outside of that criterion then you would need to apply for planning permission.
There are however a common scenario we see on a day-to-day basis which we have explained in a little more detail below.
4.1. Wraparound extensions
Perhaps you would like to make the living space on your ground floor as big as it can possibly be. Open plan living is becoming more and more popular, and the bigger that space is the better.
If you have read the above, you will see that you could build both a rear and side extension through Permitted Development. But, in some cases, to maximise space, you may want the new extension to wrap around both the side and corner of your house.
Unfortunately, this not possible through permitted development.
Planning Permission vs Permitted Development: The above 3D model shows the side and rear extensions which could be built under Permitted Development in blue. The section highlighted in red, which helps to make the new internal space far larger, would not be Permitted Development and would require planning permission.
5. I’ve heard I can now build a 6m or 8m deep rear extension
Yes, this correct, but it’s a slightly more complex process when compared to Permitted Development described above.
Legislation: To be eligible for Permitted Development Rights, each ‘Class’ specified in the legislation has associated limitations and conditions that proposals must comply with.
Prior Approval: One such condition on certain classes of Permitted Development is the need to submit an application to your Local Planning Authority for its ‘Prior Approval, or to determine if ‘Prior Approval’ will be required.
Local Planning Authority: This allows the Local Planning Authority to consider the proposals, and their likely impacts regarding certain specific factors.
Limitations: This type of extension only applies to single storey rear extensions.
Extension Depth: If you own a terraced or semi-detached house you can extend by up to 6m, and by up to 8m if you own a detached house.
Required Plans: When applying for planning permission or a certificate of lawful development, you require a full set of architectural plans which can be expensive. The good news is that Prior Approval only requires a simple site plan showing how deep your extension will be, thus saving you money.
Neighbour consultation: When your application is received, your local planning authority will consult your adjoining neighbours to advise them of your proposals.
Neighbour Objections: If any of your neighbours object to your plans, your local authority will make a decision based on how the extension might affect your neighbours’ amenity. This means: Does your extension impact their light? Does your extension appear overbearing? Does it create an increased sense of enclosure?
Permitted Development: Bear in mind that if your application is approved this does not necessarily mean your extension is ‘lawful’ in terms of permitted development. The approval simply means that you now have access to these specific Permitted Development Rights. We would always advise that you apply for a Certificate of Lawful Development where your local authority will confirm that your proposed designs meet all the relevant legislation.
6. New changes to Permitted Development
The most recent change to Permitted Development means that you could potentially add one or even two additional storeys to your house.
There are however a few limitations which you should consider first:
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.
Permitted Development legislation can be difficult to interpret. To make sure that your ideas meet the relevant legislation you can apply for what’s called a ‘Lawful Development Certificate’. This is where you would submit your plans to your local planning authority who will then confirm that your designs would not require planning permission. They will issue a certificate letting you know your plans are indeed ‘Lawful’.
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