Project: Structural Basement Waterproofing
Client: Vear Building Services Ltd / HSBC
Vear Building Services Ltd, which provides specialist services to a wide range of UK companies and retailers, recently employed Peter Cox to install a structural basement waterproofing system to HSBC premises in Streatham Hill, London.
Simon Johns, Senior Surveyor CSRT /CSSW at Peter Cox London & the South East said:
“Our first inspection of the premises suggested dampness to numerous walls with flooding of water to parts of the basement. It was apparent there was no suitable waterproofing system and because the area was going to be used for storage we recommended the installation of a Cavity Drainage Membrane System.
Producing a dry basement area requires two distinct and separate steps. Firstly, penetration of water from the ground must be stopped. This is commonly done by applying a waterproof membrane to the internal surface of the structure - or by fitting a drainage membrane.
Secondly the internal environment needs to be heated to the appropriate temperature and excess humidity created by the normal activities of the occupants must be removed. This is normally done by ensuring there is adequate ventilation (natural or forced) in the area, although in extreme cases air conditioning or dehumidification may prove to be necessary.
The British Standard (BS8102: 2009) identifies that a drained cavity system is the safest method available for those seeking maximum assurance against system failure. This is because ground water is controlled, diverted and harmlessly removed rather than being ‘blocked’ at the point of entry. Consequently the risk of increased hydrostatic pressure is reduced, where directly applied systems generally increase the level of hydrostatic pressure imposed on the structure.
“In this instance, the client wanted us to limit the water proofing to areas of the basement which suffer with water ingress,” adds Simon.
The Peter Cox team formed a perimeter drainage channels / sump to the area and installed a drainage channel leading to the sump. We installed four roding eyes to each corner section of the basement area to waterproof and then carried out a flood test to ensure that the water is fleeting to the proposed collection point.
We then fitted a sump chamber incorporating a submersible double pump unit and ran the discharge pipe into the existing internal drainage.
A DryRoom membrane system was fixed to the wall surfaces with standard fixing plugs which are sealed. Simon adds: “The plug has a dual purpose; fixing the membrane system to the wall surface and allowing studding/battens to be secured when specified, without piercing the installed system.”
We formed impervious brick piers to the base of the door areas and fixed pre-treated battens to the wall membrane and then installed plasterboard to the battened areas, prior to the application of two coats of skim plaster.
A cavity drained membrane was fixed to the floor and a chipboard floor was also installed. The substantial contract was successfully completed in 3 weeks and the building occupants now have a dry basement where they can store office supplies.
Peter Cox have extensive experience when it comes to designing and installing structural waterproofing solutions for big brands. If you have a commercial space that you think would benefit from structural waterproofing then Peter Cox are the experienced and qualified contractor for you.
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