Frequently Asked Questions

We have over the years built up a skilled workforce and established a team of experts, including surveying, planning & design, engineering and project management facilities, enabling us to offer a full design and build service, meaning our client’s have only one company to deal with. Our reputation speaks for itself.

One of the main reasons for choosing a basement conversion is the lack of suitable living space in many London properties, balanced against the cost of moving to a larger property, taking into account stamp duty, moving costs and of course, the cost of the larger property. Also, within London it is the only way to gain this amount of extra space.

Or, perhaps you just want to maximise on your property and create the leisure space you have always dreamed of, in which case you will have an investment that you can enjoy every day

We have completed a number of house refurbishments in conjunction with the construction of a new basement and are happy to look at providing a one stop shop for your entire project.
We are also happy to just do the basement element  and work with the clients fit out contractor.

What most London properties lack is sufficient living space and a basement conversion can provide a complete new floor level, providing multiple rooms that can be used for any purpose, i.e. Media Room * Playroom * Games Room* Gymnasium/Sauna * Bedroom * Nanny Suite* Swimming Pool * Bathroom * Utility or a combination of any of these – the possibilities are endless.

No, in most instances we can construct a basement where there is no cellar.

London Basement has pioneered a method of basement construction below concrete floors.

We consider 2.4M (8’0″) to be a minimum comfortable ceiling height, but in most cases it can be as high as you want, although, of course, this will affect the cost.

Yes, although this is dependant upon ground conditions and the location of the property

The majority of our clients remain in their homes during their basement conversion, which is a major advantage. We excavate in the front garden, where the window and lightwell will be. We then construct a secure covered hoarding around the area and this opening is used as our point of access throughout the works.


NO, we are happy to work with the client’s architects, engineer or interior designer. We can handle everything form start (design & planning) to finish (construction & fit out) or just complete the structural shell package.
We work with a large number of third party architects and engineers, many of whom go on to introduce new clients and projects to us.

Basement Planning permission is required when forming lightwells and creating new habitable space with Basements. As a Basement design and build company, London Basement can carry out the Basement design and planning submission on your behalf.


Very rarely, although it may have some affect on the design of the lightwell.

Yes, Party Wall awards are generally required and we will arrange for a Party Wall Surveyor to act on your behalf.

Yes, we can continue the construction of a basement below front or rear gardens, including paved driveways, ground conditions allowing.

Dependant upon the size of the area and the extent of the works, approx. 12 – 24 weeks for a standard basement conversion.

London Basement are able to offer 12 year insurance backed latent defect cover in respect of structural works. The waterproofing works are also covered by our 10 year guarantee and the cavity drain membrane waterproofing system is covered by a 30 year product guarantee.

We carry the very highest level of insurance, details available upon request.

As there are a number of factors which can affect the cost of undertaking a basement project, we feel it could be misleading to provide any costs here. Instead please call our office so that we may discuss your project and we can start to assess the likely costs for your project. After the survey, we will then provide a preliminary estimate for you, which is subject to design.