Class AD – New flats on detached buildings in use as a house
Class AD is very similar to Class AA of Part 1 and Class AC of Part 20, but this is for additional flats on top of either detached houses or bungalow – so flats on a house in the airspace!
Until the 31st July 2021 the GPDO will refer to the older use classes and not the latest revision.
If the existing property is a detached bungalow you can add one storey for a new flat or if it is a two or more storey house then you can up to two new storeys for new flats.
The building must have been constructed between 1st July 1948 and 5th March 2018. The building must not have been previously extended upwards.
One important factor is that neither the current property or future flats can be C4 via Class L or Sui Generis HMOs. You are limited to C3 dwellings only. An HMO would require full planning.
This permitted development right for flats on a house comes into force at 9am on 31st August 2020. You cannot apply before then.
See our useful table of all airspace opportunities available within the GPDO.
What else might prevent me taking advantage?
You cannot use this permitted development right of Class AD in Article 2(3) land, SSSIs, listed buildings, scheduled monuments, safety hazard area, military explosives area or within 3 kilometres(1.86 miles) of an aerodrome. Article 2(3) land includes conservation areas.
The main requirements of Class AD is as follows:
- The height of the highest part of the roof of the extended building can not be greater than 18m
- The floor to ceiling height of any additional storey (measured internally) can not exceed the lower of 1) 3m, or 2) the floor to ceiling height (measured internally) of any storey of the principal part of the existing house
- The height of the highest part of the roof of the extended building can not exceed the height of the highest part of the roof of the existing house by more than 3.5m (if the existing house consists of one storey) or 7m (if the existing house consists of more than one storey)
- Any engineering operations can not include the provision of visible support structures on or attached to the exterior of the building upon completion of the development
- Any engineering operations are limited to works (within the existing curtilage of the house) to strengthen existing walls or foundations, or to install or replace services
- Any new access to and egress from the new and existing houses can not extend beyond the curtilage of the existing house
- Any new storage, waste or other ancillary facilities can not extend beyond the curtilage of the existing house
- Any new storage, waste or other ancillary facilities can not be situated on land forward of a wall that either 1) forms the principal elevation of the existing house or 2) fronts a highway and forms a side elevation of the existing house.
There a few considerations that the local authority will need to consider as part of the prior approval. These are transport & highways impacts, air traffic and defence assets, contamination, flood risk, external appearance, natural light in all habitable rooms, impact upon amenity space of the existing building and neighbouring ones, overlooking/privacy/loss of light, impact on a protected view identified in the Directions Relating to Protected Vistas.
Application
Class AD requires a Prior Approval application to the local authority and should be decided within 8 weeks or 56 days. You will need to supply floor plans. You will also need to submit a flood risk report if required and information on the various considerations that the local authority will need to consider. There is however no deemed consent if the decision has not been made within this period of time.
Full legislation
The full legislation issued on 21st July 2020 says…..
Class AD – New dwellinghouses on detached buildings in use as dwellinghouses
Permitted development
AD.—(1) Development consisting of works for the construction of new dwellinghouses immediately above the topmost storey on a detached building in use as a single dwellinghouse within the meaning of Class C3 of the Schedule to the Use Classes Order, where the development comprises—
(a) up to two additional storeys, in the case of an existing dwellinghouse consisting of two or more storeys;
(b) one additional storey, in the case of an existing dwellinghouse consisting of one storey,
together with any development under sub‑paragraph (2).
(2) Development consisting of any or all—
(a) engineering operations reasonably necessary to construct the additional storeys and new dwellinghouses;
(b) works for the construction of appropriate and safe access to and egress from the new and existing dwellinghouses, including means of escape from fire, via additional external doors or external staircases;
(c) works for the construction of storage, waste or other ancillary facilities reasonably necessary to support the new dwellinghouses.
Development not permitted
AD.1.Development is not permitted by Class AD if—
(a) the building was constructed before 1st July 1948 or after 5th March 2018;
(b) on 5th March 2018 the building was in a use other than—
(i) a use falling within Class C3 (dwellinghouses) of the Schedule to the Use Classes Order; or
(ii) a use or mixed use within paragraph AA(2)(a) or (b) of this Part;
(c) the additional storeys are constructed other than on the principal part of the dwellinghouse;
(d) the floor to ceiling height of any additional storey, measured internally, would exceed the lower of—
(i) 3 metres; or
(ii) the floor to ceiling height, measured internally, of any storey of the principal part of the existing dwellinghouse;
(f) the new dwellinghouses are not flats;
(g) the height of the highest part of the roof of the extended building would be greater than 18 metres;
(h) 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 dwellinghouse by more than—
(i) 3.5 metres, where the existing dwellinghouse consists of one storey; or
(ii) 7 metres, where the existing dwellinghouse consists of more than one storey;
(i) the existing dwellinghouse has been enlarged by the addition of one or more storeys above the original building, whether in reliance on permission granted under Class AA of Part 1, or otherwise;
(j) development under Class AD(2)(a) would include the provision of visible support structures on or attached to the exterior of the building upon completion of the development;
(k) development under Class AD(2)(a) would consist of engineering operations other than works within the existing curtilage of the dwellinghouse to—
(i) strengthen existing walls;
(ii) strengthen existing foundations; or
(iii) install or replace water, drainage, electricity, gas or other services;
(l) development under Class AD(2)(b) would extend beyond the curtilage of the existing dwellinghouse;
(m) development under Class AD(2)(c) would—
(i) extend beyond the curtilage of the existing dwellinghouse;
(ii) be situated on land forward of a wall forming the principal elevation of the existing dwellinghouse; or
(iii) be situated on land forward of a wall fronting a highway and forming a side elevation of the existing dwellinghouse; or
(n) the land or site on which the dwellinghouse is located, is or forms part of—
(i) article 2(3) land;
(ii) a site of special scientific interest;
(iii) a listed building or land within its curtilage;
(iv) a scheduled monument or land within its curtilage;
(v) a safety hazard area;
(vi) a military explosives storage area; or
(vii) land within 3 kilometres of the perimeter of an aerodrome.
Conditions
AD.2.—(1)Where any development under Class AD is proposed, development is permitted subject to the condition that before beginning the development, the developer must apply to the local planning authority for prior approval of the authority as to—
(a) transport and highways impacts of the development;
(b) air traffic and defence asset impacts of the development;
(c) contamination risks in relation to the building;
(d) flooding risks in relation to the building;
(e) the external appearance of the building, including—
(i) the design and architectural features of —
(aa) the principal elevation; and
(bb) any side elevation that fronts a highway; and
(ii) including the impact of any works under paragraph AD(2)(b) or (c);
(f) the provision of adequate natural light in all habitable rooms of the new dwellinghouses;
(g) impact on the amenity of the neighbouring premises including overlooking, privacy and the loss of light;
(h) 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 the provisions of paragraph B (prior approval) of this Part apply in relation to that application.
(2) Any development under Class AD is permitted subject to the following conditions—
(a) the materials used in any exterior work must be of a similar appearance to those used in the construction of the exterior of the existing dwellinghouse;
(b) following the development, the roof pitch of the principal part of the building must be the same as the roof pitch of the principal part of the existing dwellinghouse; and
(c) the development must not include a window in any wall or roof slope forming a side elevation of the building.
(3) Any development under Class AD is permitted subject to the condition that it must be completed within a period of 3 years starting with the date prior approval is granted.
(4) The developer must notify the local planning authority of the completion of the development as soon as reasonably practicable after completion.
(5) The notification referred to in sub-paragraph (4) must be in writing and must include—
(a) the name of the developer;
(b) the address or location of the development; and
(c) the date of completion.
(6) Following the development, every dwellinghouse in the building must remain in use as a dwellinghouse within the meaning of Class C3 of the Schedule to the Use Classes Order and for no other purpose, except to the extent that the other purpose is ancillary to the primary use as a dwellinghouse.
Page updated 21st August 2020