New Build Basement Waterproofing

Stronghold Preservation provides a basement waterproofing design service in accordance with BS 8102:2009. 

BS 8102 recommends that a specialist basement waterproofing contractor be included in the design team at an early stage in the design process.  From our experience, early inclusion in the design is the most successful and cost effective; and is the most likely way for the client to achieve their goal without compromise.

We at Stronghold Preservation provide a 10 year insurance backed guarantee for all basement waterproofing where we have provided the design detail, and installed the basement waterproofing system.

There are a number of basement waterproofing systems on the market; we have chosen to be accredited to those systems which we believe offer the best, problem free solution to providing a dry basement for your new build home or building.  All our surveyors and operatives are fully trained in basement waterproofing.

The optimum basement waterproofing system is dependent on the quality of the basement required.  Basements are classified into 4 grades:

  1. Carparks & non-electrical plant rooms - some seepage and damp
  2. Plant rooms, workshops & retail storage - no damp, but moist environment
  3. Habitable rooms; residential, offices etc - dry environment required
  4. Controlled environment; museums, etc - controlled, totally dry environment

Cavity Drain Basement Waterproofing Systems

The retaining wall in the cavity drain basement waterproofing system should be built as per the engineers specifications, and should provide some resistance to water seepage.  Insitu concrete provides more resistance to water penetration than masonry, and is therefore the preferred construction method.  A drain is installed at the base of the retaining wall, and a dimpled basement waterproof membrane mechanically fixed to the retaining wall.  Any water which does seep through the retaining wall is depressurised, and drips into the cavity drain.  The water is then removed from the drain by a sump and a pump, or through an open elevation, into the storm drainage.  This waterproofing system is a water management system, which deals with the water which may seep through the retaining wall, giving an extra layer of protection.

Basement Waterproof Barrier Systems

The structure relies on a waterproof internal or external membrane to prevent water ingress into the internal basement environment; eg bonded sheet membranes, cementitious tanking, bentonite matting. This system relies on holding back the water, and requires the workmanship to be 100% defect free.  Any defects in the barrier will allow water to seep into your basement or cellar.

Integral Basement Waterproofing

The basement waterproofing is designed into the retaining walls, through the use of waterproof concrete, or similar, and is most commonly used in underground car parks, swimming pools and lift pits.  The concrete will have additional mesh or reinforcing within it to try and prevent cracking (which would allow water ingress), as well as waterbars at joints, which will swell on contact with water, preventing water seeping any further.

Combined Basement Waterproofing Systems

A combined basement waterproofing system is required where the likelihood of water ingress is high, the consequences of leakages is unacceptable, or where unacceptable water vapour could occur.  A combined system uses  two or more of the above waterproofing systems, combined; for example, a barrier system in conjunction with the cavity drain system, and therefore gives the best possible protection to your basement.


BS 8102:2009

BS8102 is a design document which informs the designer on basement waterproofing and assists in the correct specification of those systems.  It states that for a basement waterproofing system to be successful it must deal with groundwater, soil gases and contaminants and that these should be considered from early planning and design stage; a specialist waterproofing company is to be included in the design team from an early stage, so that the waterproofing design is an integral part of the design process.

The general principle of BS8102 is to select a basement waterproofing system capable of providing the required internal environment, by reducing the risk of water reaching the internal environment.  However, it notes that workmanship and materials cannot be 100% defect free, and requests that a contingency plan is put into place to manage any water that bridges the retaining wall, as a secondary measure to prevent water entering the internal environment.