Tuesday, 6 December 2016

Basement excavation may not be permitted development

I have been extremely busy for the past few weeks, and so there has been an inevitable hiatus in posting items on this blog. The blog is concerned with the whole range of legal issues affecting town and country planning, but today I find myself returning once again to the issue of permitted development under the GPDO, this time under Part 1 of the Second Schedule to the Order.

Basement developments (especially in London) have been the subject of controversy for a number of years. As a general rule, it has been assumed that many such developments are permitted development (as discussed below), although some LPAs have made Article 4 Directions, so that in those areas a planning application will be required for basement extensions.

The legal background is theoretically straightforward, but it is in the detail that difficulties have arisen. Section 55(2)(a) of the 1990 Act is often cited as authority for the proposition that building operations which affect only the interior of a building or which do not materially affect the external appearance of the building are not to be taken to involve development of the land. As originally enacted, the predecessor of this section would have had the effect of exempting from the definition of development building operations to provide additional living space by forming or extending a basement under an existing house. However, section 55(2)(a) does not exempt works begun after December 5, 1968 involving the provision of additional space in the building underground. So digging a basement does constitute ‘development’ for the purposes of section 55.

The necessary planning permission for basement works is provided in most cases by Part 1, Class A of the Second Schedule to the GPDO. This permits the enlargement, improvement or other alteration of a dwellinghouse and, in principle, none of the exclusions or limitations in that Class would prevent the excavation or enlargement of a basement as permitted development. However, an interesting judgment was delivered in the High Court on 2 December in the case of Eatherley v. Camden LBC [2016] EWHC 3108 (Admin), which indicates that there may be practical limitations on such developments.

This was an application for the judicial review of a Lawful Development Certificate issued by Camden LBC, whereby they had confirmed that it would be lawful to carry out proposed works comprising the excavation of a basement beneath the footprint of the existing dwellinghouse. The proposed depth of the basement was approximately 2.85m, with the width (side to side of the house) a maximum of 4.5m and length (front to back of house) a maximum of 7.5m. A single internal staircase was proposed to link the existing ground floor with the proposed basement.

One issue that the council had considered was whether the engineering activities associated with basement construction were within Class A. Local residents had claimed that the proposals involved excavation works which, as a matter of fact and degree, constituted “an engineering operation” which did not benefit from any permitted development right under Class A. The council’s officers had concluded that the basement works would, by necessity, involve temporary engineering works associated with protecting the structural stability of the house and neighbouring building. However it was considered that these works would be entirely part of the basement works to the house, and that they would not constitute a “separate activity of substance” which would not be ancillary to the activity that benefitted from permitted development rights.

However, this issue was the basis of the legal challenge to council’s decision in the High Court, namely (1) that the proposed development included a substantial engineering operation which was not within the permitted development right relied upon in the LDC, (2) that the Council misdirected itself in concluding that the engineering works proposed were not a separate activity of substance, and (3) that the interpretation of the Class A permitted development right as including the engineering works proposed in this case frustrated the legislative purpose of section 59 of the 1990 Act [the enabling power under which the GPDO was made] and of the GPDO itself, and was therefore ultra vires. In the event, only the second of these submissions was accepted by the Court, although this was sufficient in itself to require the quashing of the LDC.

I haven’t got time to summarise Cranston J’s very interesting and instructive discussion of the background to these permitted development rights, but it is well worth reading in its entirety. In Cranston J’s view, the crucial issue was the meaning of the plain words of the planning permission granted by Article 3(1) of the GPDO for the Classes of development described as permitted development in Schedule 2. In relation to Part 1, Class A the issue revolves around the meaning of “the enlargement, improvement or other alteration of a dwellinghouse”.

The difficulty with a basement development, his lordship observed, is the absence of any boundaries to the permission. Yet there must be a point where the excavation, underpinning and support for a basement for a dwellinghouse becomes an activity different in character from the enlargement, improvement and alteration of that dwellinghouse. For that reason, engineering operations for the basement are at some point different in character to those involved in the preparation of foundations for a house.

The answer, drawn from the legal authorities, is whether, as a matter of fact and degree, the single process of making the basement amounts to different activities, each of substance, so that the one is not merely ancillary to the other. The principal authority relied on was : West Bowers Farm Products v. Essex CC (1985) 50 P & CR 368, as applied in Wycombe DC v. SSE [1995] JPL 223 and this was the law that Cranston J applied.

The first of these cases was concerned with agricultural PD under Part 6. The proposal in that case was for an irrigation reservoir on a farm of some 18 acres in extent and 6.5 metres in depth. The construction of the reservoir necessitated the extraction of large quantities of sand and gravel, which were to be sold. The Court of Appeal (upholding the judgment at first instance) held that if the development involves two activities, each of substance, so that one is not merely ancillary to the other, then both require permission. In that case, the Court was in no doubt that the construction of the reservoir would involve two activities, each of substance. The extraction of so much gravel would not merely be ancillary to the carrying out of the engineering operations under Part 6. This was a question of fact and degree.

In the Wycombe case, the front garden of a dwellinghouse in an elevated position above the adjoining road was almost totally excavated, leaving a hard standing for vehicles level with the road - 6.8 metres wide, 4.5 metres deep and 2 metres in height at the rear. The Secretary of State decided on appeal that there was no breach of planning control because what was done was permitted under Part 1, Class F. However, the High Court held that the Secretary of State had not determined what was incidental to the provision of a hard surface. He had referred to the “sole purpose of the excavations” and went on to find that “the removal of the necessary quantity of earth to achieve that aim took place as an integral part of the operation”. However, the Secretary of State was fatally in error in omitting to consider the correct test, and in applying tests which were not appropriate.

In the present case, Cranston J held that in the context of an original “two up two down” terrace house in suburban London, the development of a new basement, when there is nothing underneath at present, could well amount, as a question of fact and degree, to two activities, each of substance. There is the enlargement, improvement and alteration aspect, but there is potentially also an engineering aspect of excavating a space and supporting the house and its neighbours. That is the position, even though the latter is necessary to achieve the developer’s aim; indeed is indivisible from it. If there is this separate aspect in the development, it requires planning permission. The Class A right grants planning permission for one of the two activities of the development but not for the engineering aspect.

The officer’s report, advising the Council to grant the certificate, accepted that the basement works would, “by necessity”, involve temporary engineering works associated with protecting the structural stability of the host and neighbouring buildings. However, it added, these would be “entirely part of the basement works”, and did not constitute a separate activity of substance which would not be ancillary to the activity that benefitted from permitted development rights. In Cranston J’s judgment, the planning committee asked itself the wrong question with its focus on the works being “entirely part” of the overall development, which would “by necessity” involve engineering works. It concluded that because this was the case it followed that the works did not constitute a separate activity of substance.

That is not the approach laid down in the authorities. The Council’s conclusion that the engineering works were not a separate activity of substance followed from a misdirection. It should not have asked itself whether the engineering works were part and parcel of making a basement but whether they constituted a separate activity of substance. The Council needed to address the nature of the excavation and removal of the ground and soil, and the works of structural support to create the space for the basement.

In other words, if the planning committee had asked itself the right question, it would have needed to assess the additional planning impacts of the engineering works to decide whether they amounted to a separate activity of substance. It would have been in a somewhat difficult position in undertaking that task without any description of the engineering works required in support of the application, although it may have been able to draw on its own experience of the common and predictable ramifications of this type of basement development with this type of terrace house in this area. The issue was one of planning judgment, but since the planning committee misdirected itself as to the issue, it never got as far as properly exercising that judgment.

The LDC was therefore quashed on this ground.



  1. Interesting that a committee was used to determine a LDC application.

    Also interesting is the case raised regarding creating a hard-standing/parking area. It has long been the practice in some LPAs I have worked for to require a planning application where significant excavation or other engineering works were required in connection with this operation, for the reasons Cranston explains. Why this had not been interpreted this way in relation to basement developments until this case is perplexing.

  2. Thank you Martin, very useful. I remember cases in the 70s where the planners said the removal of soil under a dwelling constitued development because planning control was concerned with works on, over and under ground.

  3. I've always found this odd. Surely a bog-standard residential extension would require excavation for the foundations and structural calculations (dealt with via building control), why is this any different?

  4. The Architects' Journal is reporting this as 'Court decision means tougher rules for basement extensions', i.e, that they must have planning permission if they require excavation and engineering works.

    The article is behind a paywall unfortunately, otherwise I'd provide the link.

    I find the decision rather baffling; I can't think of a situation where a basement extension (comprising 'development') wouldn't require excavation and engineering works, so I wonder if there is any situation in which Part 1, Class A may any longer apply to basements.

    Presumably, the Article 4 directions are now redundant?

  5. The essential point in these cases, as confirmed by Eatherley, is that it is always going to be “a matter of fact and degree” as to whether the necessary excavations to form or extend a basement under an existing house should be seen as merely ancillary to the “the enlargement, improvement or other alteration of a dwellinghouse” by “the provision of additional space in the building underground”, or whether the extent of those engineering operations is so great as to constitute "a separate activity of substance”.

    I take the point raised by correspondents that there are likely to be many cases where the engineering works involved do amount to a separate activity of substance, which will therefore require planning permission. Nevertheless, if an LPA wishes to avoid disputes arising on this issue, then an Article 4 Direction would put the matter beyond doubt, if the LPA feels that such developments are a problem in their area.

  6. But the 'matter of fact and degree' argument cannot work in practice. bcause it only becomes a consideration if the developer applies for a lawful development certificate. Unless the developer anticipates selling the property within 4 years then surely the best advice is for them to proceed as before, and not bother with the lawful development certificate.

  7. The “matter of fact and degree” approach is not an argument; it is the way this issue has to be determined, either in relation to an LDC application or in relation to enforcement action.

    Passer-by’s suggestion would be a high risk strategy. If basement excavations were to start without warning, this would almost certainly arouse the concern, and quite probably the ire, of neighbours who would then complain to the LPA, thus prompting an enforcement investigation, followed quite possibly by the threat of enforcement action unless a planning application for the basement works is submitted.

    An LDC application may be the only safe way forward, if it is thought that the proposed basement extension is in fact PD under Part 1, Class A. However, in light of Eatherley, it seems that many basement excavations will in fact be "a separate activity of substance”, which will require full planning permission.

    The Eatherley judgment may well prove to be a significant game changer where basement extensions are proposed in future.


  8. I seem to recall that rebuilding a dwelling (wholly or substantially) even of identical external appearance, constitutes development requiring planning permission.

    Building some larger basements involves rebuilding the foundations of a dwelling, and could be a substantial part of the dwelling.

    A different approach to the issue but perhaps helps a little in thinking what was intended to be controlled by planning permission and what benefits from general consent via the GPDO.

  9. In answer to CT (9 December), there is no doubt that the creation or extension of a basement under a house constitutes development, because section 55(2)(a) says so in clear terms. CT is correct in pointing out that rebuilding a dwelling, even if the replacement is of identical appearance, constitutes development requiring planning permission, but in light of section 55(2)(a) it is unnecessary to speculate whether or not some basement developments might fall into this category; because they constitute development in any event. The question is whether or not this falls within the development permitted by Article 3(1) and Part 1, Class A in the Second Schedule to the GPDO. Ministerial advice is unhelpfully silent on this issue. However, the judgment in Hibbitt (following West Bowers Farm Products v. Essex CC and Wycombe DC v. SSE) now confirms that there is a definite test. It will still (as always) be “a matter of fact and degree” in each case, but it should be easier to determine whether the necessary engineering operations amount to “a separate activity of substance” requiring planning permission.

    One other thought has occurred to me since I wrote the blog post above. It is potentially possible that some LPAs may wish to revisit cases in which basements have been formed or extended, but where the development was substantially completed less than 4 years ago. In practice, there may be some doubt as to whether it would be practical or realistic to require that the development be undone and the building be restored to its pre-existing form, and so it would hardly be ‘expedient’ (section 172) to take enforcement action in such circumstances. However, where work has only just started, or is only now getting under way, it could well be ‘expedient’ for the LPA to take enforcement action in the absence of planning permission having been obtained.

  10. I've just read the Eatherley judgment. I can just about understand (although not necessarily agree) that there's a distinction to be made between the formation of a basement, and the associated works of providing underpinning and temporary supports - but I still don't see why this takes it out of the realm of permitted development (and into the realm of planning), as none of the issues it raises are planning matters. Instead, they're all aspects of development that would seem to me to more properly belong to the realm of Building Control.

  11. In response to Passer-by, the point about the Eatherly judgment is that whilst building operations are permitted by Part 1 of the Second Schedule to the GPDO, engineering operations are not permitted development within this part of the Second Schedule. So if operations are involved that go beyond a reasonable definition of ‘building’ operations, such as extensive excavations, these will be seen as engineering operations “amounting a separate activity of substance”, and so will fall outside the scope of PD.