On 1 August changes to the current permitted development regime will be introduced. These will assist in meeting housing demand, whilst ensuring that conversions to residential use provide adequate natural light.

The Permitted Development Rights (England) Order 2015 describes what permitted rights are available in England, how a person may avail themselves of those rights, and what planning conditions are imposed when they do. As such they offer a great deal of flexibility, avoiding the cost, delay and uncertainty of submitting planning applications for approval by the local planning authority.

The government has added to this flexibility with amendments to the 2015 Order whilst at the same time introducing a restriction to ensure new homes constructed under permitted development rights have sufficient natural light. The following come into effect on 1 August 2020.

Upwards extension on existing blocks of flats

Upwards extension as a permitted development right has been mooted for 18 months or more. From 1 August an additional two floors of new flats may be constructed on existing detached blocks of flats under what is known as Class A of Part 20. The new rights include the engineering operations necessary to support the new floors, the right to move existing roof-based plant and equipment, and the construction of safe access to serve the new floors.

There are quite a few restrictions on this new right. They are only available when the existing building has no less than three above ground floors, and was constructed after 1 July 1948 but before 5 March 2018. There are restrictions on the height of each new floor, and on the relative and maximum heights of the building, so that extended building may not exceed 30 metres in height. The rights are not available if the building is in a conservation area or a National Park, or if the building is listed. There is also a restriction if the building is within 3km of an aerodrome.

These restrictions will mean that the rights will not apply to every existing block of flats. A careful assessment of whether the rights do apply is needed at the outset.

If the rights are to be relied upon then conditions apply. The primary condition is the requirement to submit a ‘prior approval’ application to the planning authority. Under the prior approval process the planning authority can consider a prescribed but narrow set of planning considerations. These include a consideration of the building’s external appearance and impact on the amenity of the existing building and neighbouring properties. Through this prior approval process the impact of overlooking, privacy and loss of light will be scrutinised, and where these impacts are considered unacceptable, the prior approval application may be refused. Refusals can be appealed. 

This ‘planning application light’ process will be attractive where favourable circumstances exist. What will make these rights particularly attractive is that reliance on them will not trigger the requirement to deliver costly section 106 planning obligations or highway improvement. However, where a Community Infrastructure Levy (CIL) Charging Scheme is in place, CIL will apply.

Adequacy of natural light

Class O of the 2015 Order already allows the change of use of offices to residential development.

This permitted development right is regularly used and many offices have already been converted to homes.

The Class O permitted development right did not grant the right to do any works, such as the creation of new external windows or doors. This has not deterred some developers who have converted some existing offices into windowless new homes.

In response to the national outcry the government has amended Class O so that now the prior approval by the planning authority also includes the consideration of the adequacy of natural light in all habitable rooms in the new homes.  If the conversion would result in insufficient natural light in any habitable room, then the planning authority must refuse the prior approval application. Without that prior approval the development will not proceed under Class O unless the refusal is successfully appealed, and that is unlikely as the refusal is mandatory, not discretionary. In these circumstances, unless windows can be lawfully installed, the office to residential conversion will not be able to proceed.

Contrast this with the Class Q permitted development right. Class Q allows the conversion of agricultural buildings to dwellings. This permitted development right includes those building operations reasonably necessary to convert the building to a home, such as windows and doors. So although the need to consider the adequacy of natural light is now also required prior to reliance on Class Q, under these rights the developer can lawfully install the windows necessary to satisfy the planning authority on this point.

TLT has extensive experience in advising on permitted development rights. If you would like to discuss your matter, please get in touch.

This publication is intended for general guidance and represents our understanding of the relevant law and practice as at June 2020. Specific advice should be sought for specific cases. For more information see our terms & conditions

Written by


Fergus Charlton

Date published

30 June 2020


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