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April 20, 2016

With space a premium and opportunities to build upwards hindered by stringent planning restrictions, the UK’s appetite for basement design has soared, particularly in London.  However, HSE has reported that a huge number of basements design projects still do not meet health and safety regulatory standards.

The GSE team have completed an array of basement design projects; from wine cellars to large underground complexes that extend underneath the whole footprint of the house, complete with sub basements allowing for swimming pools and home cinemas.

Our vast experience of complex projects has put our firm at the forefront of basement design, working alongside some of London’s best architects and specialist basement companies.

SO HERE’S OUR GUIDE TO BASEMENT DESIGN:

1. CAN ANY HOUSE HAVE A BASEMENT CONVERSION?

Most properties can yes. Modern houses that are built on raft foundations or piled foundations can prove problematic to underpin especially if they are part of a terrace. It is also problematic when houses are near rivers and ground water is present.

2. WHAT ARE THE COSTS INVOLVED WITH BASEMENT DESIGN?

Typically for the basement construction, which would be the reinforced concrete and waterproofing the expected costs will range from approximately £2000 – 4000/ft. The fit out is additional and costs will very much depend on client taste and specification.

3. WHAT IS THE ANTICIPATED PROJECT COMPLETION TIME?

It really depends on the size of the property and the contractor appointed. Typically a smaller basement of say 40mwill take 3 – 4 months to complete while a much bigger basement can be on site for over 12 months and even longer including the fit out.

4. WHAT EXPERT SKILLS DO I NEED TO ENLIST?

The three essential professional consultants needed will be an architect, structural engineer and party wall surveyor if the property is adjacent to or near other properties. It is also a very good idea to get a competent contractor who has done underpinning and basement design work before.

5. WHAT ABOUT WATERPROOFING?

The BS8102 is the British Standard for the protection of below ground structures against water from the ground. You can refer to this guide for structural waterproofing but a structural engineering firm will also be able to advise.

Waterproofing (or tanking) is when you block out water using a waterproof barrier that is installed internally, externally or sandwiched within. Another way of blocking out water is through waterproof concrete – something more common in new build buildings today.

Depending on the intended use of the basement conversion, BS8102 offers different grades of protection based on the purpose of the building. 

A RECENT GSE BASEMENT DESIGN PROJECT IN HOLLAND PARK

The GSE team were recently involved in the landscaping and structural design of a basement conversion at a private residence in Holland Park.

An area of land to the rear of our clients property was developed with the construction of a new build pavilion and large subterranean swimming pool, spa and gym complex.

The project involved the excavation of a new basement which was to house the new swimming pool, gym and changing areas.

Due to planning restrictions the entire pool structure was built 10m below ground level and the garden above reinstated and landscaped. The pavilion was built as a guest house having immediate access to the landscaped garden, the swimming pool and entertainment area below.

Green Structural Engineering are passionate about innovative and smart structural design, with the majority of our work coming through repeat business and referrals. If you have a questions about basement design or any other structural engineering query, please do not hesitate to get in touch with a member of our award winning team.