Upwards extensions | Permitted development rights Skip to content

Rob Sellen | 12th April 2022

Using permitted development rights for upwards extensions


Rob Sellen | 12th April 2022

Using permitted development rights for upwards extensions

A landmark case provides the first legal interpretation of how conditions are considered when using permitted development rights for upwards extensions.

Last month we were provided with a landmark decision from the High Court which closely examined how the conditions relating to an application for prior approval for upwards extensions are interpreted. CAB Housing Ltd v Secretary of State for Levelling Up, Housing and Communities [2022] EWHC 208 (Admin) may assist developers and councils in interpreting the scope of controls that are exercisable when considering an upwards extension of a building. Upwards extensions are authorised by the permitted development rights contained within the General Permitted Development Order 2015 (as amended) (the GPDO).

Extensive changes to the GPDO were enforced in August 2020 and introduced permitted development rights which enabled the provision of additional storeys, as well as creating additional separate residential units on top of existing buildings. They included the following which all require prior approval to be sought before commencing development.


Schedule 2 Part 1 Class AA Building upwards to create additional storey on dwellinghouse (householder extension)
Part 20 Class A Building upwards to create dwellinghouses on detached blocks of flats
Class AA Building upwards to create dwellinghouses on detached commercial or mixed use buildings
Class AB Building upwards to create dwellinghouses on detached commercial or mixed use buildings in a terrace
Class AC Building upwards to create dwellinghouses on detached dwellinghouses
Class AD Building upwards to create dwellinghouses on dwellinghouses in terrace


Permitted development rights effectively grant planning consent for specific developments as described in the relevant parts of the GPDO. Although, an element of control is withheld within these rights, whereby they can only be exercised following a successful application to the local planning authority for ‘prior approval’.

An application for prior approval is different to that of a planning application. In the former, the local planning authority is limited as to what they can consider. The GPDO uses conditions to specify the matters which should be considered when determining an application for prior approval. For example, and relevant to the landmark case, these may be:

  • the impact on the amenity of any adjoining premises including overlooking, privacy and loss of light; and
  • the external appearance of the dwelling house, including the design and architectural features of the principal elevation and any side elevation which fronts a highway.

The interpretation of the conditions, including those listed above, were the subject matter of last month’s landmark court case. The judgment provided a greater steer as to whether only adjoining premises abutting the property are subject to the application. It also considered whether architectural considerations and the proposed appearance are limited only to the property in isolation, or whether regard should be had to the impact of the proposed appearance on neighbouring properties and the overall street scene.

Mr Justice Holgate presiding over the case in question examined three planning appeal cases which were dismissed by the planning inspectorate. In dismissing these appeals the inspectors adopted a broader approach in regards to amenity and the proposed external appearance.

The claimant’s argument was that – in their opinion – the inspector should not have contemplated anything beyond the scope of the matters which should be considered, and that the planning inspectors acted ultra vires in their approach to deciding these planning appeals.

Whereas, the defendant’s position was that the broader approach adopted in making these decisions fell within their powers. This approach was consistent with the wording introduced initially by the 2018 version of the National Planning Policy Framework (NPPF), which contains support for “opportunities to use the airspace above existing residential and commercial premises for new homes”. Provided that these opportunities were “consistent with the prevailing height and form of neighbouring properties and the overall street scene, is well-designed (including complying with any local design policies and standards), and can maintain safe access and egress for occupiers”.

Now, turning to the three appeal decisions in question which were examined by the landmark case. The first related to a proposed upwards extension of a single storey bungalow. This was proposed under Schedule 2, Part 1, Class AA of the GPDO at 31 Gaywood Avenue in Hertfordshire. The Inspector dismissed the appeal on the grounds of the unacceptable appearance of the proposal, stating that it would ‘standout discordantly within the residential street scene’, and that the rear of the proposed extension when viewed from the gardens of the neighbouring properties would be a consideration (despite the GDPO only drawing attention to aspects which front a highway). The second appeal related to 20 Frankling Street in Haringey and concerned another upwards extension, this time above a terrace dwelling to provide an additional storey. In this case, the Inspector dismissed the appeal on the grounds of how the proposal would be seen in relation to neighbouring buildings and the wider street scene and that the proposed appearance is not, therefore, a matter to be assessed in a vacuum or in isolation. Lastly, a further appeal case, this being at 2 Lemsford Close, also in Haringey was examined. In this appeal case the Inspector gave weight to the impact of the proposed additional storey to the existing two-storey house, stating that the proposal would give the terrace an uneven profile and would have a disruptive effect on the open aspect of the street scene.

In the landmark case it was upheld that the Planning Inspectors in these appeals were lawful in their approach in considering the wider merits such as the impact on the surrounding street scene and the environment, however this may be construed by some to go well beyond what the GDPO is asking the decision maker to consider. The summary of the case clarifies that:

  • the interpretation of ‘adjoining premises’ is not restricted to the neighbouring properties immediately next door;
  • the impact on amenity is not limited to overlooking, privacy and loss of light; and
  • the assessment of ‘external appearance’ is not limited to parts of the proposals which is only viewed from the highway and are to be considered in the context of the surrounding area.

As we approach two-years since the introduction of these radical provisions within the GPDO, we reflect on how the proposals made through this regime have fared in reality.

Since August 2020, there has been an increased appetite for developers, home owners and landlords who wish to exercise these rights and extend properties upwards to either create new dwellings or simply enlarge their homes. However, as recent case law shows, it is not always as straight forward as it sounds and requires careful consideration. The table below provides an overview of the extent to which these permitted development rights have been exercised since they were enacted and how they have fared in councils’ decision making.


Total* Granted Refused % Approved
Schedule 2 Part 1 Class AA 425 208 217 49%
Part 20 Class A 121 44 77 36%
Class AA 29 10 19 34%
Class AB 19 4 15 21%
Class AC 16 9 7 56%
Class AD 8 5 3 63%
* Correct as of the end of Q4 2021 and does not include applications where PA was not required


The snapshot above does not paint the most positive view of how some have benefited from the introduction of these new permitted development rights.

However, on the appeal side, since the enactment of these permitted development rights, the Planning Inspectorate has received and decided over 80 s.78 appeal applications for refused prior approvals for upwards extensions, with around 60% of these being allowed, overturning the local planning authorities decisions.

The effect of appearance and the impact on the wider character of the area are consistent issues which are arising, particularly in the appeal decisions. It is therefore expected that the recent landmark High Court decision will help to address and provide a steer on the considerations which should be taken into account when proposing an upwards extension through permitted development rights.

At Paris Smith we have a full range of planning and legal services to assist you in your projects. If you would like any advice on planning, please contact me, or a member of our Planning team.

Read my colleague, Rachel Montgomery’s recent blog, for further guidance on other legal issues that should be considered when exploring the potential to add additional storeys.

Stay up to date with our latest industry news

By completing your details and submitting, you are consenting to us sending you relevant legal updates and invitations based on the areas of interest you select. For further details please read our privacy notice.