Viewpoint: Basement Extension Policy


The title of Jonathan Coe’s 11th novel ‘number 11’, is of course the official home of the Chancellor of the Exchequer. It is also the number of levels in an extravagant multi-storey Chelsea basement planned by one of the main characters in the book. “What is the lady of the house going to put there?” asks a visitor to the house. “Nothing,” replies the harassed project manager.

Of course the book is fictional and it would no doubt be structurally and practically impossible to implement such feat of engineering. Moreover, it would be expected that the basement would be used as an import accessory to the house such as a home-cinema or swimming pool. However, the reference serves as a satirical example of the number and extent of basement extensions which have been developed in London over recent years.

The prevalence of basement extensions has led to a number of inner/central London Boroughs issuing Article 4 Directions removing the permitted development rights pursuant to Schedule 2, Part 1, Class A of the Town and Country Planning (General Permitted Development) (England) Order 2015. This piece of legislation, in certain instances allows single dwelling houses to construct basement extensions without the need to submit a planning application. Kensington and Chelsea was the first borough, in March 2016, closely followed by Westminster to implement Article 4 Directions restricting this permitted development; whilst Camden’s non-immediate Article 4 Direction comes into force in June 2017.

In addition the Department of Communities and Local Government have recently been gathering information in a call for evidence exercise on the number, extent and impact of basement extensions which some sceptics may see as early indicators of basement extensions being removed from the General Permitted Development Order.

With the turn of the tide moving away from so called ‘iceberg properties’, this begs the question; is the time now up for basement extensions? The answer in the short term is no. However, it is going to become increasingly more onerous, time consuming and frustrating to get basement extensions through planning.

The pioneer of basement extension policy is RBKC which in their recently published its Consolidated Local Plan 2015 contains Policy CL7 and relates specifically to basement extensions. Policy CL7 contains no less than 14 ‘thou shalt’ restrictive criteria which in combination with the Basements Supplementary Panning Document are used to determine applications for basement extensions in the borough. A key obligation of this policy is the significant amount of front loading the Council now places on the submission of information upfront in order to determine the applications. Such is the case that in the application submission a Construction Traffic Management Plan, Pre-planning Consultation and Flood Risk Assessment is now required in order to even validate the application. It could be argued that this places a significant amount of upfront risk on the applicant without any guarantee the proposal would receive planning permission. Although, a more positive spin on this would be that front loading the application would, assuming the abundance of reports comply with the SPD, give more reassurance to the applicant that the development would not be refused on a technical or spurious reason for refusal.

A recent project involving the redevelopment of a mews house and a perusal of the committee agenda and associated decisions involving basement extensions in RBKC has taught us that although there are a number of hoops to jump through, which were previously not required, basement extensions are still possible and are now an accepted form of development in certain areas. It is not a matter of principle rather a question of detail in most instances.

The emergence of reactive policy to basement extensions and the much discussed shortage of available land in areas of central London serve to prove that basement extensions are here to stay, however, boroughs will be exercising an increasing amount of control over them and their direct and perceived impact.

Extending a simple mews house which was intended to be occupied by domestic workers with a multi-layered basement extension inclusive of an underground swimming pool invariably changes the character of the property. However, it should not be seen as a negative, rather, it should be viewed as a contribution to the social and evolving history of the property. Whist we are not advocating 11 storey basements as such. If London cannot expand outwards into the greenbelt, it needs to look at other ways to grow and downwards is a more visually acceptable way than upwards in the long term. Basements are also a recognised way of adding value to a property without compromising essential greenspace.

By Richard Seaward