The Only way is up: Permitted Development Rights for Upward Extensions Class AA)

What are Permitted Development Rights?

In short, permitted development rights are a list of alterations and changes you can make to a property without having to apply for planning permission, providing you do not live in an area with an Article 4 Direction.  If you want to know more take a look at our FREE eBook, Town Planning, The Basics…Permitted Development & Use Class for more information.

Can I Add an Additional Storey to my Home?

In theory yes – but don’t get too excited about this yet, as there is always a catch! Some new permitted development rights have recently been put in place, allowing you to extend your property upwards. This is known as Class AA, or ‘enlargement of a dwelling-house by construction of additional storeys’.

The idea behind the introduction of this was that it may help provide extra space for growing families, whilst aiding economic recovery from the COVID-19 pandemic.

What’s the Catch?

As with any permitted development rights, there are some important conditions to be aware of. And for this kind of development, prior approval (a simpler alternative to a full planning application) is required.

Additionally, to make use of this permitted development right, your dwelling must:

  • Have been built after 1st July 1948 and before 28th October 2018.
  • Not be on 2(3) land, for example a conservation area, national park, an area of outstanding natural beauty or a site of special scientific interest.
  • Not have had permission granted by a change of use under Class M, N, O, P, PA or Q of the Town and Country Planning (General Permitted Development) Order 2015.
  • Not have already been extended upwards above the original house, whether through Class AA permitted development or another means.
  • Not interfere with a protected view.
  • Have no windows in the wall or roof slope on the side elevation in additional storeys.
  • Follow the roof pitch of the existing house.
  • Not be taller than 18 metres after the work is completed.
  • Have visually similar materials used in the new storeys to those in the original house.
  • Continue to be used as a house after extension.

How Tall can the Upwards Extension be?

This depends on what type of house you’re working on, you can add up to 2 storeys where the existing property has 2 or more storeys or one storey on a bungalow. For example, the new roof must not:

  • Exceed the height of the highest point of the existing house by 3.5 metres in a one storey, detached house.
  • Exceed the height of the highest point of the existing house by 7 metres in a two storey, detached house.
  • Exceed the height of the next tallest house by 3.5 metres, if the house is in a terrace.
  • Exceed the height of the adjoining building by 3.5 metres, if semi-detached.

If your proposed development doesn’t satisfy some of these points, don’t panic! It doesn’t necessarily mean you won’t be able to do it, it just means you will need to apply for formal planning permission.  Our eBook Town Planning, The Basics…Application Process covers what you need to know if you need planning permission for a development.

 What Should I Include in my Prior Approval Application?

Although prior approval is a simpler process than applying for planning permission, there are still a few things you definitely need make sure are included:

  • A detailed description of the proposed development.
  • Scaled plans that indicate north.
  • Existing and proposed elevations.
  • Plans detailing the positioning and dimensions of any new windows.
  • A written statement including the number of dwellings proposed (and how many already exist).

What can a Local Planning Authority consider?

Its not automatic that a prior approval application will be granted, a Council must consider a number of things when assessing these proposals such as:

  • transport and highways impacts;
  • air traffic and defence asset impacts;
  • contamination risks;
  • flooding risks;
  • the external appearance of the building;
  • the provision of adequate natural light in all habitable rooms;
  • impact on the amenity of the existing building and neighbouring premises including overlooking, privacy and the loss of light;
  • impacts of noise from any commercial premises;
  • impacts on other premises carrying out any trade, business or other use of land in the area;
  • protected view (these are very specific to site in London i.e. between St. Pauls Cathedral and Alexandra Palace etc); and
  • where the existing building is 18 metres or more in height, the fire safety of the external wall construction of the existing building.

If the Council is concerned about any one of these issues prior approval can be refused.  There is a right of Appeal, take a look at our Free eBook on Appeals or our blog on Knowing your options before embarking on this route.

What else does Class AA cover?

Class AA also allows for the construction of up to two new storeys on some existing buildings above ground level in commercial or mixed use as shops (classes A1, A2, A3 B1(a) (now class E), betting shops, payday loan shops or laundrettes). These buildings must:

  • Be detached and free-standing
  • Be three storeys or more above ground level

For more information on permitted development rights for upward extensions, including within other classes like AB (flats on terraced buildings in commercial or mixed use), AC (flats on terraced buildings in dwellinghouse use) and AD (flats on detached buildings in dwellinghouse use), consult a town planner or take a look at The Town and Country Planning Order 2020.

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