Basement Developments: Make the Most of Your Home - GBW

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Basement Developments – Making The Most of The Ground Beneath Your Feet


With land in short supply, especially in cities, particularly London, developers and home owners continue to look for alternative ways to create further living space, and converting existing cellars to habitable space or creating entirely new basements is a convenient solution.  According to analysis by the Halifax the increase in planning applications for basement development went up by 183% between January 2012 and December 2016.

This is further compounded by research carried out by Direct Line which shows an increase of 9% in basement applications in the UK between 2013 and 2015 of which the vast majority (75%) are in London.  The demand has been so high that in some boroughs, such as Kensington & Chelsea or Pimlico, you are now no longer able to undertake basement conversions.


basement housing


Legislation & Building Regulation Requirements

There is a lot of additional legislation and building regulation requirements to comply with when constructing or developing a basement – overall design and engineering issues, party wall issues, rights of light and ground water problems, tree root protection, biodiversity, sustainable drainage and amounts of daylight available in habitable accommodation are just a few.  It is also vital you select the right contractor who has good PI cover and plenty of experience in basements.


Impact on Neighbours

You also need to consider the impact of such a development on neighbours, as basements and lofts cause real divides amongst neighbours.  High profile cases include Led Zeppelin guitarist Jimmy Page who has been in dispute with pop star Robbie Williams over Williams’ plans to create a two-storey basement beneath his home in Kensgington.

Jon Hunt, (Foxton’s Estate Agency) has had objections from the French Embassy over his plans to build a multi-storey basement in his Kensington home and the jailed fraudster Achilleas Kallakis left his neighbours with a giant hole in the ground after his Grade II listed townhouse was seized mid-way through an enormous basement construction.


Additional Considerations

Additional considerations include: highway and parking problems, dust, noise and vibration disturbance and planners often require developers to sign up to a Considerate Construction Scheme.

The table below, provided by The Basement Information Centre (TBIC), is a useful tool in summarising the requirements & benefits for different types of basements.


Type of Basement Description Details Benefits Comments
Refurbishment Alterations to existing space below ground. May require lowering the floor to increase head room; underpinning adjacent walls; improving ventilation and lighting. Typically involves improvements to, or new, waterproofing system; and new finishes and fixtures. – Adds value and desirability of property.
– Additional usable space.
– Addresses potential existing damp problems.
– Provides opportunities for new activities in property e.g. games room/gym/storage.
Building regulations approval will be required for any works. Planning permission may be required, depending on extent of works and extended use.
New Garden Basement New basement adjacent to existing property, usually in a garden space. New structure below ground, with planted green roof or terrace at garden level. Access from main house via new external covered staircase. – Adds value and desirability of property.
– Additional usable space.
– Provides opportunities for new activities in property.
– Potential for natural daylight and ventilation through roof lights.
Planning and building regulations approval required.
Likelihood of need for structural support to existing house is reduced as distance from the house increases.
New Basement Under New Housing Basement space built as part of a new build development. Arrangements of windows and internal and external access vary. Designed to suit current and future use requirements, site conditions, cost, and constructability. – Adds value and desirability of property.
– Future adaptability.
– Usable space for sustainable technologies and recycling.
– Potentially reduces footprint of house.
– Increases thermal performance.
No additional building or planning regulation requirements, provided it is included in the initial application.
Retrofit New space created through excavation below ground floor of an existing property. Allows creation of additional space below business or homes, which benefit from staying in the same location. Preservation of existing building possible (e.g. listed building). Underpinning works required. – Adds value to property.
– Additional space for business to develop in same location or family to expand.
– Releases potential of empty property.
Planning and building regulations approval required.
Specialist work. Generally only economically viable for high land value properties.
Deep Basements Spaces that are below one storey deep. Frequently used for car parking, plant services space, and storage below larger residential development and other uses including commercial, retail, or mixed use schemes in urban areas. – Building footprint and development potential optimised above ground.
– Parking and space for deliveries possible.
Refer to The Concrete Centre guide ‘Concrete Basements’


Although a large number of the basements being developed (especially in London) are for the luxury end of the market, creating high-end living spaces, leisure areas and multi level car parking, there is an increasing trend for home owners to use the money that it would cost to move, to improve an existing space.

What can I use my Basement for?

The choice, of course, is yours and you probably already have a very specific purpose in mind for your basement conversion. However, for those that are looking for inspiration here are some of the more common uses:

  • Bedroom
  • Bathroom
  • Shower room
  • Playroom
  • Home Gym
  • Home Office
  • Games Room
  • Entertainment/media room
  • Study
  • Home recording studio

A guide to finishing the basement.

Navigating Planning Permission for Basement Conversions

Typically, converting an existing basement or cellar into a living space, classified as a ‘change of use’, doesn’t necessitate planning permission. However, constructing a new basement, significantly enlarging one, or altering the property’s external appearance (for instance, by adding a light well) does require planning permission, according to the Government’s planning portal.

Lowering the floor of a cellar to increase its height might also need planning permission. However, small-scale extensions and modifications usually fall under Permitted Development Rights. For listed buildings, consent is generally required for internal and external alterations.

It’s prudent to obtain written confirmation from your local planning office that the work can proceed without planning permission. This is valuable documentation when selling the property, demonstrating compliance with planning requirements.

Adhering to Building Regulations for Basement Conversions

Transforming a basement into a habitable room mandates compliance with Building Regulations, focusing on safety and energy efficiency. These regulations encompass fire escape routes, ventilation, ceiling height, damp proofing, electrical installations, and water supply. The Basement Information Centre provides comprehensive guidelines on these standards.

However, renovating an existing livable basement or repairing a cellar without changing its use does not fall under these regulations.

Fire Safety Considerations in Basement Spaces

Building Regulations emphasise fire safety, particularly regarding escape routes in basements. The regulations stipulate the necessity of a viable escape route in case of fire. This could be an external door or window of specific dimensions (refer to the Basements for Dwellings Document) or a protected stairway leading to an exit.

Further information on fire safety regulations specific to basements can be found in relevant safety guidelines.

Dealing with Party Walls During Basement Conversions

If your property shares walls with neighbouring buildings, the Party Wall Act 1996 becomes relevant. This requires informing the owners and leaseholders of adjoining properties about the conversion. A Party Wall Agreement, which might cost around £700 per neighbour, is often necessary in these cases.

Basement Flooding

How can my basement flood?

If you are experiencing damp in your basement, it can be difficult to pinpoint the source of the water. Without knowing the cause, it makes you vulnerable to flooding. Low-lying areas are more at risk, especially those below the flood plane.

The following are the more common causes of basement flooding:

1) Groundwater – a simple process where rainfall makes the ground damp that then leads to a damp basement wall

2) Surface flooding – from a heavy storm or overland flooding

3) Burst water pipes – water from faulty or damaged pipes

4) A high water table – areas with a high water table are prone to flooding

5) Poor landscaping – if soil slopes down to the house rather than sloping away from the house for the first ten feet as it should

6) Poor quality concrete floors – cracks or faults in the flooring

7) Issues with a draining system including problems with a sump pump


More on basement waterproofing to prevent flooding

More inspiration on what your basement conversion could look like.

For further information please contact Ed or Kelly on Tel: 01284 365345 or email /

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