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Class AA – new dwellinghouses on detached buildings in commercial or mixed use

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This allowance is effected by the changes to the Use Classes Order and it is anticipated that this allowance will be tidied up in August of 2021 in line with the current government consultations. Reference to the Use Classes should be taken from the pre-2020 Use Classes Order.

What is allowed

Development consisting of works for the construction of up to two additional storeys of new dwellinghouses immediately above the topmost storey on a detached building to which is—

  • used for any purpose within Class A1 (shops), Class A2 (financial and professional services), Class A3 (restaurants and cafes) or Class B1(a) (offices) of the Schedule to the Use Classes Order, or as a betting office, pay day loan shop or launderette;
  • in a mixed use combining—
  • two or more uses above; or
  • a use falling within Class C3 (dwellinghouses) of the Schedule to the Use Classes Order, together with one or more uses above

together with any or all

  • engineering operations reasonably necessary to construct the additional storeys and new dwellinghouses;
  • works for the replacement of existing plant or installation of additional plant on the roof of the extended building reasonably necessary to service the new dwellinghouses;
  • works for the construction of appropriate and safe access and egress to access to and egress from the new and existing dwellinghouses, including means of escape from fire, via additional external doors or external staircases;
  • works for the construction of storage, waste or other ancillary facilities reasonably necessary to support the new dwellinghouses.
Where can I use it

On existing purpose built detached buildings listed above and subject to the following restrictions.

What is not allowed

Development is not permitted by Class A if—

  • above ground level, the building is less than three storeys in height;
  • the building was constructed before 1st July 1948 or after 5th March 2018;
  • on 5th March 2018 the building was in a use other than—
  • a use or mixed use within the above uses or
  • a use falling within Class C3 of the Schedule to the Use Classes Order;
  • the additional storeys are constructed other than on the principal part of the building;
  • the floor to ceiling height of any additional storey, measured internally, would exceed the lower of—
  • 3 metres; or
  • the floor to ceiling height, measured internally, of any storey of the principal part of the existing building;
  • the new dwellinghouses are not flats;
  • the height of the highest part of the roof of the extended building would exceed the height of the highest part of the roof of the existing building by more than 7 metres (not including plant, in each case);
  • the height of the highest part of the roof of the extended building (not including plant) would be greater than 30 metres;
  • development under Class AA would include the provision of visible support structures on or attached to the exterior of the building upon completion of the development;
  • development under Class AA would consist of engineering operations other than works within the existing curtilage of the building to—
  • strengthen existing walls;
  • strengthen existing foundations; or
  • install or replace water, drainage, electricity, gas or other services;
  • in the case of Class AA development there is no existing plant on the building;
  • in the case of Class AA development the height of any replaced or additional plant as measured from the lowest surface of the new roof on the principal part of the extended building would exceed the height of any existing plant as measured from the lowest surface of the existing roof on the principal part of the existing building;
  • development under Class AA would extend beyond the curtilage of the existing building;
  • development under Class AA would—
  • extend beyond the curtilage of the existing building;
  • be situated on land forward of a wall forming the principal elevation of the existing building; or
  • be situated on land forward of a wall fronting a highway and forming a side elevation of the existing building; or
  • the land or site on which the building is located, is or forms part of article 2(3) land;
  • a site of special scientific interest;
  • a listed building or land within its curtilage;
  • a scheduled monument or land within its curtilage;
  • a safety hazard area;
  • a military explosives storage area; or
  • land within 3 kilometres of the perimeter of an aerodrome.
How do I use the allowance

This is a complex prior a approval permitted development allowance that should not be attempted without the support of a planning consultant and as such it is subject to an assessment of the following criteria:

  • transport and highways impacts of the development;
  • air traffic and defence asset impacts of the development;
  • contamination risks in relation to the building;
  • flooding risks in relation to the building;
  • the external appearance of the building, including—
  • the design and architectural features of the principal elevation; and any side elevation that fronts a highway; and
  • the impact of any works of Class AA;
  • the provision of adequate natural light in all habitable rooms of the new dwellinghouses;
  • 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 on the intended occupiers of the new dwellinghouses;
  • impacts of the introduction of, or an increase in, a residential use of premises in the area on the carrying on of any trade, business or other use of land in the area;
  • whether, because of the siting of the building, the development will impact on a protected view identified in the Directions Relating to Protected Vistas dated 15th March 2012 issued by the Secretary of State, and
  • where the existing building is 18 metres or more in height, the fire safety of the external wall construction of the existing building,
  • compliance with the National Standards from 6th April 2021
Our Notes

Early Class AA applications have been universally refused (based on research carried out by Planner Magazine). It remains to be seen how effective Class A is in reality and at the time of writing it is untested at appeal.

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