Expert Insights

Expert Insights

Permitted Development: A right to construct new dwellings

A new right applies to allow the upward extension of purpose-built blocks of flats in England. Whilst it will present opportunities for some owners / developers, the circumstances in which it can be used are relatively limited. Also, the factors which require local planning authority consideration by way of a “prior approval” mechanism are extensive. Care is needed to ensure that the permitted development right applies – and that all necessary works fall within the scope of the right.

What is the new right?

From 1 August 2020, a new permitted development right will allow you to construct up to two additional storeys of new flats immediately above the existing topmost residential storey on a purpose-built, detached block of flats. The new flats can be used as dwelling-houses under class C3 of the Use Classes Order and for ancillary purposes only.

The right also covers the following works where reasonably necessary:

  • Engineering operations within the existing curtilage to strengthen existing walls or foundations or to install or replace services, but cannot include visible support structures attached to the exterior.
  • Works to replace existing plant or install new plant on the roof of the extended building to service the new flats, but only where there is existing plant on the building.  The replaced or additional plant cannot exceed the height of existing plant measured as specified in the Regulations.
  • Works within the curtilage to construct appropriate and safe access and egress to the new and existing flats, including fire escapes, via external doors or staircases.
  • Works within the curtilage to construct storage, waste or other facilities to support the new flats. These cannot be placed on land forward of the wall of the principal elevation or forward of the wall of a side elevation fronting a highway.

Are there any limitations or restrictions?

Yes, lots! The building must be a “block of flats”, consisting of self-contained premises which were built as flats and remain as such with ancillary facilities for occupiers. This appears to rule out premises including other non-ancillary uses.  “Detached” means that the building must not share a party wall with a neighbouring building.

The rights do not apply to:

  • conservation areas, areas of outstanding natural beauty, the Broads, national parks and world heritage sites, SSSIs, safety hazard areas, military explosives storage areas or within 3km of an aerodrome perimeter
  • listed buildings and scheduled monuments, or land within their curtilage
  • buildings converted to residential under permitted development rights
  • building of less than 3 storeys above ground level
  • buildings constructed before 1 July 1948 or after 5 March 2018

The floor to ceiling height of any additional storey must not be more than 3 metres in height or, if less, the floor to ceiling height of any existing storeys, measured internally.  The overall height of the roof of the extended building cannot be greater than 7 metres higher than the highest part of the existing roof (excluding existing plant). The extended building (excluding plant) cannot be greater than 30 metres in height. The additional storeys must be constructed on the principal part of the building ie the main part, excluding lower front, side or rear extensions whether original or added on.

Consideration also needs to be given to the standard provisions of the General Permitted Development Order, including where environmental impact assessment may be required and where existing permissions disapply permitted development rights.

Are any approvals needed?

Yes, you must apply for the “prior approval” of the LPA in relation to the following factors:

  • impacts on transport / highways and air traffic / defence asset
  • contamination and flood risk
  • external appearance and the provision of adequate natural light in all habitable rooms
  • the impact on the amenity of the existing and neighbouring residents including on overlooking, privacy and the loss of light
  • impacts on certain protected views

You must also provide a report on construction management, covering the hours of operation and how adverse impacts of noise, dust, vibration and traffic will be mitigated.

The application for prior approval must comply with the detailed requirements of the Regulations including a work specification and floor plans. Site notices, neighbour notifications and consultation of certain third parties are required, giving the opportunity for representations to be made which must be taken into account.

The development cannot begin until prior approval is received (which may be conditional). There is no deemed approval provision. Prior approval can be refused if the LPA thinks that the proposal does not comply with the Regulations or insufficient information has been provided.

How long do I have to do the works?

Development must be completed within 3 years from the date prior approval is granted in accordance with the approved details.

This article was written by Claire Fallows and Lydia O'Hagan, for more information, please contact Claire on or T: +44 (0)20 7427 1046 or Lydia on or T: +44 (0)20 7427 6533. 

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