Waterproofing Systems

Basement waterproofing by Surrey & London Basement Company Ltd

Basement conversions, basement construction dig-outs, basement or cellar refurbishment and creating space below-ground are increasingly more popular. The most important consideration is a waterproofing system. To make absolutely sure the basement is waterproof, the ground water pressure is effectively managed away to prevent water penetration into the property that will otherwise destroy the dry living environment.

Guidance Note:

If you are considering a basement conversion, there are a number of points to consider:

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  • Tanking (waterproofing) walls and floors below external ground level and the junctions between them should be protected with a waterproofing system. This is to prevent ground moisture reaching the internal surface of the wall or upper surface of the floor, to maintain satisfactory environmental conditions within the basement for the intended use.
  • Consideration should also be given to the position of the water table - whether it is high, low or varies significantly throughout the year.
  • There are several different ways in which basement walls and floors can be waterproofed. Whatever method used should be appropriate for resisting ground water pressure and should have British Board of Agreement (BBA) or similar independent technical accreditation.
  • One should bear in mind that good attention to detail and good workmanship are important for the tanking to be successful. All this means that neglected, mouldy, dark, musty and even flooded basements can be transformed into wonderful cosy, light and tranquil living spaces.
  • The basement waterproofing used by Surrey & London Basement Company Ltd is recognised by British Standards BS8102. It is quoted in approved publications, including Building Regulations, as the most effective and least likely to fail, type C.
  • Our Surveyors are Certified Surveyors in Structural Waterproofing (CSSW) and we pride ourselves in our highly skilled and technically proficient team. We can design water-tight management systems for any structure and can effectively advise the architect, chartered surveyor, main contractor or structural engineer of your choice on the design of the system, giving them freedom from liability under their own professional indemnity. Equally, we can provide all the expertise you require.

There are two ways to waterproof an existing, underground basement:

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  • The most familiar is commonly referred to as cellar or basement tanking. It is also known as resistive waterproofing and, as its name suggests, waterproofs by resisting the ingress of water from the ground into the structure. It is quite effective if professionally applied and is totally reliant on the strength of the building. However, because it is so hard, it has a tendency to crack under vibration from heavy road traffic or movement in the structure. This type of waterproofing is described as type A tanking and, whilst perfectly acceptable, carries a much higher risk of failure than type C.
  • We use type C waterproofing as a preferred option. It is the system least likely to fail, the most forgiving and easy to maintain once installed. It is called cavity drainage membrane (CDM) and works by lining basement walls and floor with waterproof membranes that allow for firstly building in and then decoration and other practical applications. A cavity is left between the original wall and the membrane down which any water can pass into specially constructed drainage channels and sumps in the floor of the basement. The water is then silently pumped away to a suitable drainage point. This system works exceptionally well as no pressure builds up and so induces minimal extra stresses on the structure. Simple, effective, completely safe and much less expensive than you think.
  • This all contributes to ultimately producing a dry basement; once achieved and properly guaranteed you are free to continue with your basement construction and to apply the space in whatever way you wish - bedroom, bathroom, gym; in fact with basement conversions and in a dry basement with tanking,  you can simply pick what you want.

Contact us on 0844 257 3535 to arrange a survey or use the contact form to the right.