Have your say on basement excavation rules

A regular concern raised with my by residents in Ravenscourt Park Ward is about their neighbours basement excavations. Due to the high level of Stamp Duty the housing market is distorted. Those who move to a bigger property are penalised so instead create more room in their existing homes. Quite understandable. But it is also understandable that many are concerned by overdevelopment causing a structural risk to adjoining homes. The prospects of months of noise and dust also fills people with a sense of gloom.

I have asked the Council for an update on its development plan policies regarding basement excavations.

David Gawthorpe, the Deputy Team Leader Development Plans, replied:

“The council’s existing policy on basements is included in the Development Management Local Plan (2013) – see policy DM A8. This policy is supplemented by additional policy guidance included in the Planning Guidance Supplementary Planning Document (2013).  However, as you may be aware, the council is expected soon to approve an emerging new Local Plan for public consultation and subsequent submission to the Secretary of State for independent examination before adoption in 2017. This emerging Local Plan was considered by Cabinet on 4 July and is scheduled to go to Full Council for approval on 20 July. Consultation will begin in September.

“Within the emerging Local Plan there is a revised basement policy, known as policy DC11. This policy is more detailed than existing policy DM A8 and includes numerous criteria that will need to be met if planning applications for basements are to be permitted, including protection of gardens and provision of a construction method statement to be submitted with planning applications.  We expect the policy to attract the interest of developers and houseowners and could be a topic that is discussed at the examination.  

“In addition, the council intend to put in place an Article 4 Direction to remove permitted development rights for basements in the borough, thus enabling the council to assess all basement developments through the planning application process. The proposed Article 4 Direction requires a period of consultation and consideration by the Secretary of State and is anticipated to be in place by Summer 2017, at the same time as the adoption of the Local Plan.

“The council is also preparing a revised Supplementary Planning Document (SPD) to supplement the emerging Local Plan. This document will supersede the currently adopted Planning Guidance SPD and will include further guidance on basement development, supplementing Local Plan policy DC11. This SPD also requires a period of public consultation and will be adopted alongside the Local Plan in 2017.

“I would also advise that the council’s noise and nuisance team have the powers to dictate what type of work can be carried out and when it can be carried out. A notice can be served under the Control of Pollution Act and officers dealing with excavations would be able to impose strict start times on heavy duty drilling and limits to how long such work could continue before ensuring there is a suitable break. Each site has its own characteristics and officers from the team would need to visit to decide on the best way of protecting neighbouring residents. Whilst there is no way to control the number of sites in operation officers from the noise and nuisance team will do their best to control the impact of the sites.”

The draft local plan is here.

But the relevant section on basements is as follows:

Policy DC11 – Basements and Lightwells

New basements and extensions to existing basements will only be permitted where they:

a. do not extend into or underneath the garden further than 50% of the depth of the host building measured from the principal rear elevation;

b. do not extend into or underneath the garden further than 50% of the depth of the garden;

c. are set back from neighbouring property boundaries where it extends beyond the footprint of the host building;

d. do not comprise more than one storey. Exceptions may be made on large sites;

e. do not result in any adverse impact on the amenity of adjoining properties or on the local, natural and historic environment;

f. are designed to minimise the risk of flooding to the property and nearby properties from all sources of flooding;

g. include a minimum of one metre of soil above any part of the basement beneath a garden;

h. ensure that the basement helps reduce the volume and flow of surface water run-off through appropriate use of SuDS and will provide active drainage devices to minimise the risk of sewer flooding;

i. ensure that lightwells and railings at the front or side of the property are as discreet as possible and allow the scale, character and appearance of the property, street or terrace to remain largely unchanged;

j. are designed to safeguard the structural stability of the existing building, nearby buildings and other infrastructure;

k. provide a Construction Method Statement (CMS) (carried out by a qualified structural or civil engineer) to be submitted with planning applications for all basement projects; and

l. ensure that traffic and construction activity does not cause unacceptable harm to pedestrian, cycle, vehicular and road safety.

New self contained basement flats will not be permitted in the Environment Agency’s Flood Zone 3 areas where there is a risk of rapid inundation by flood waters in the event of a breach of the river’s flood defences, unless a satisfactory means of escape can be provided.


6.236 For the purposes of this policy, a basement is considered to be a floor of a building which is partly or entirely below ground level. A ground or lower ground floor with a floor level partly below the ground level (for example on a steeply sloping site) will therefore generally be considered basement development.

Size of Basements

6.237 The council recognises the benefits of new residential basement and lightwells in meeting housing needs and residents aspirations. It will permit basements but subject to a number of criteria being met, that will safeguard the quality of life. The council will 152 LB Hammersmith and Fulham Proposed Submission Local Plan 2016 (Full Council) 6 Borough-wide Policies allow extensions of houses and flats into the basement below the building, providing there is no adverse impact on the amenity of neighbouring properties (such as flooding) or negative impact on the street scene due to the need for the provision or alteration of lightwells.

6.238 The policy criteria states that basements should not exceed 50% of the garden area and not exceed 50% of the depth of the host building. Restricting the extent of basement excavations to any approved extension and limiting the depth of excavation to a single storey will help to limit the extent and duration of construction. This will help to reduce the impact of basement construction on local residents. This criterion applies to the front garden, the rear garden and gardens to the side of the property individually, rather than calculated as an aggregated garden area for the whole property. The unaffected garden must be in a single area and where relevant should form a continuous area with other neighbouring gardens. Sufficient margins should be left between the site boundaries and any basement construction to sustain growth of vegetation and trees.

6.239 On large sites, basements of more than one storey may be permitted in certain circumstances. These will generally be new developments located in a commercial setting or of the size of an entire or substantial part of an urban block. They should be large enough to accommodate all the plant, equipment and vehicles associated with the development within the site and offer more opportunity to mitigate construction impacts and carbon emissions on site. These schemes will be expected to provide appropriate evidence to demonstrate to the Council’s satisfaction that the development does not harm the built and natural environment or local amenity or increase flood risk. For the purposes of this policy, large sites are considered to be: new major developments, for example schemes which comprise 1000m2 additional non-residential floorspace or 10 or more additional dwellings; large schemes located in a commercial setting; or developments the size of an entire or substantial part of an urban block.

6.240 A ‘single storey’ is considered to be one that cannot be subdivided in the future to create additional floors. It is generally about 3 to 4 metres floor to ceiling height but a small extra allowance for proposals with a swimming pool may be permitted.”

So do take part in the consultation in September and also let me know your thoughts.

One thought on “Have your say on basement excavation rules

  1. Maybe the new administration will consider a reduction of stamp duty? Surely few people would bother with the expense and hassle of digging a basement if the taxes on moving house were not so onerous.

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