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Digging deep: Issues with basement developments

Recent newspaper headlines recount stories of bizarre proposals by owners to enlarge their substantial London houses by digging down to create several levels under the building and under the garden, to house swimming pools, cars and wine collections!

On a more everyday scale, for most of us the cost of property in London and the expense of selling and buying, including the increase in Stamp Duty Land Tax, renders moving house a costly decision and in some cases those costs are prohibitive. Families continue to grow and the owners’ needs for extra or different space change over time. If you live in a city, where space is at a premium, digging out an existing basement or cellar or creating new levels underground and going outwards under the garden can be an attractive option.

Whilst by their nature basement developments may have less visual impact on the neighbourhood than a rear or roof extension, they do raise other issues. The nature of the works means that the construction process involves major structural work to existing buildings and that can prompt concern amongst neighbours about the effect on the structural stability of nearby buildings. The removal of dug out waste can lead to noise and disturbance during the construction process and issues of management of works traffic, plant and equipment during that time.

In London terraces the works will invariably impact on party walls or structures with neighbouring properties and the procedures under the party wall legislation will need to be followed.

Local authorities have noticed a marked increase in the number of applications for consent to such works over recent years. They have expressed concern at the impact on the quality of life and living conditions for nearby residents and consider this to be a material planning consideration of which they should take heed.

Both Kensington & Chelsea and City of Westminster councils have taken steps to restrict the size of the basement proposals to which they will consent, with the aim of limiting the extent and duration of construction works, for example, by limiting the extent of basement development to one storey and to not exceed more than 50% of the garden.


If you are considering such an option then you must approach the local planning authority at an early stage to ascertain their approach to your proposals.

Also bear in mind the perceived and actual impact on neighbours and the possibility that might give rise to vigorous opposition in the public planning process and even a breakdown in relations generally.

If you would like any further information or guidance, please contact:

Karen Mayne
Partner, Property

T. 020 7227 7273


This briefing is for guidance purposes only. RadcliffesLeBrasseur LLP accepts no responsibility or liability whatsoever for any action taken or not taken in relation to this note and recommends that appropriate legal advice be taken having regard to a client's own particular circumstances.

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