Planning a basement conversion – how to gain planning consent for a basement extension to your London home

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If you are considering taking out any major construction work, including a basement, the first hurdle you may be faced with is obtaining planning permission.

Each borough has its own set of planning regulations that can vary even from street to street, particularly in conservation areas where regulations tend to be even stricter. Ultimately, if you are lucky enough to live in a listed building, you may well require listed building consent as well as or instead of planning consent, and the regulations will potentially govern even small changes to the inside of the property as well as the exterior, regardless of whether the property is listed as Grade II, II* or Grade I (the most special and prized buildings).

What do councils look for in planning applications?

The council’s main objectives will be concerned with the following:

  • Maintaining the look of the property externally to ensure the property is in keeping with the neighbouring properties.
  • Ensuring your proposals do not have a negative impact on light levels or overlooking for your neighbours.
  • For conservation areas and listed buildings, preserving heritage properties and original features, views of and around the property.

Companies such as BasementWorks can be employed to secure basement planning permission for such extensions, carefully tailoring plans and specifications to meet the rigorous restrictions individual councils apply to their decision making, ensuring every planning application will be successful.

At BasementWorks we are particularly proud of our planning knowledge – we have a 100% success rate for achieving planning consents for our clients’ projects. All our end-to-end basement packages include our full planning service for our clients’ ease and peace of mind.

Not all boroughs approach basement plans the same way

In some boroughs, certain types of applications require a myriad of supporting documents just to be validated for consideration. The most demanding applications typically involve basement extensions and conversions, as these potentially create the greatest impact upon the property and neighbouring homes.

Nevertheless, planning applications have risen by 22%* over the last year as a result of the stagnant housing market. The demand for converting existing living spaces into the ideal home is ever increasing.

As a result, in London, the Royal Borough of Kensington & Chelsea (RBKC) and Westminster City Council now require extremely detailed and specialist plans and reports on the size, location and depth of the basement, as well as how the works will be carried out, including environmental impacts such as traffic routing, minimising air pollution and noise control.  Wherever basements are prevalent, not just in RBKC and Westminster, planning rules have changed significantly over recent years, to ensure that basement disturbance is kept to a minimum.

Get started by finding precedent in planning decisions

It’s worth investing time into researching on your local council’s planning database, comparing consents that have been granted on your street to neighbouring properties, or failing that, other similar streets in your borough. That will give you a strong indication of what you can achieve in your property.

If this sounds somewhat daunting, get a planning consultant to do this for you and you will soon form a pretty good idea of what to expect you could achieve.

Whilst some houses are ripe for a loft conversion, others may be deemed unsuitable due to the historic roof line, or overlooking neighbouring properties. BasementWorks can guide you through the issues and advise on the best solutions.

Other permissions and consents you need for a basement extension

Something to bear in mind before starting on the path of a basement conversion is the additional consents and agreements you may require.

  1. Party Wall Awards – for any works that are “notifiable” to your neighbour, i.e., are deemed by party wall regulations as potentially impacting upon neighbouring buildings. Even works to neighbouring detached houses may be notifiable.
  1. Freeholder Consent to the works – if you are a leaseholder and do not own the freehold of your building.
  1. Building Control approval – whether you ask your architect or building company to obtain consent from the local authority prior to works commencing, or your contractor serves notice and arranges an inspector to visit the site during works to sign off on the quality, a major construction project should be carefully planned to ensure the work is safe, both for your use but also during construction. Basements conversions in London are now a very highly regulated area in the construction industry – the Health and Safety Executive (HSE) frequently make spot checks on basement construction sites to ensure health and safety standards are up to scratch. You can check whether a building company has any notices filed on them through the HSE website:
  1. Considerate Contractors – most London boroughs now require your basement specialist to be a member of this scheme, ensuring their commitment to minimising disturbance to neighbours.

Basement Works is a specialist basement company, building exceptional basements across London. For any advice on planning a basement project, please get in touch with one of our experts on 020 8877 0555 or email to find out more.

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