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On a daily basis we field enquiries about the best strategy for waterproofing a new-build basement. The waterproofing method adopted for a new-build basement requires careful consideration as failure to make the correct decision can have a major impact on the effectiveness of the system and the potential use of the basement. In addition, consideration has to be made for the repair of the waterproofing system if failure were to occur and the consequential loss and the legal disputes resulting from the failure.
Implications of BS8102 for Waterproofing A New-Build Basement
In deciding the method for waterproofing a new-build basement it is advisable to follow the recommendations within BS8102:2009 ‘Code of Practice for Protection of Below Ground Structures Against Water From the Ground’. The standard advises on the types of waterproofing available and confirms the performance grade to be achieved:
Type of Waterproofing:
- Type A (Barrier) protection – A barrier to water ingress is applied to the inner or outer surface of the structure
- Type B (Structurally Integral) protection – The structure is formed as a watertight construction and requires no additional protection
- Type C (Drained) protection – Water entering the structure is received by planned cavities or voids and safely removed
Grades of Waterproofing Protection:
- Grade 1 – Some water seepage and damp is tolerable depending on the intended use. Car parking, plant rooms etc.
- Grade 2 – No water penetration is acceptable. Damp areas are tolerable depending on the end use. Plant rooms, workshops etc.
- Grade 3 – No dampness or water penetration is acceptable – Ventilated residential and commercial areas such as homes, offices, shops etc.
Recommendations From BS8102
– Site Investigation Regarding Geology, Hydrogeology and Topography
Where comprehensive site investigation is not possible, or the results are inconclusive, the designer should design both the structure and the waterproofing of the structure to be able to deal with a full head of hydrostatic water pressure – full saturation of the ground.
– Inclusion of a Waterproofing Specialist as Part of the Design Team
A “Waterproofing Specialist” should be included as a part of the design team so that an integrated waterproofing solution is created. All design decisions made by others that might have an impact on the waterproofing design should be brought to the attention of the waterproofing specialist/designer or installing contractors. Final decisions and any recommendations should be approved by the specialist. Newton Specialist Basement Contractors (NSBC) fill the role of ‘Waterproofing Specialist’
– Combined Waterproofing Systems
Consideration should be given to the use of combined protection (i.e. Type A plus Type B, Type A plus Type C or Type B plus Type C) where in a single system: a) the likelihood of leaking is high, b) the consequences of leakage is unacceptable, c) additional vapour checks are necessary for a system where unacceptable water vapour transmission could otherwise occur. The decision to use a combined approach of two or more types of waterproofing will always be based up on a risk vs cost calculation. Often other factors will dictate the use of a second or third type of protection, such as ground gasses or aggressive agents found within the ground water.
Newton Combination Waterproofing Solutions
Other waterproofing requirements such as protection at podium decks, pile caps etc. can be successfully waterproofed using Newton waterproofing systems, often using a combination of systems and products.
Newton Specialist Basement Waterproofing Contractors
Whether waterproofing a new-build basement or an existing structure, we will always recommend that the preferred waterproofing system be installed by one of our registered contractors. When involved in the design they are able to offer insured guarantees for both the installation and the design of the waterproofing system, and with most of our contractors having suitable PI allowing you to delegate the full design liability for the waterproofing aspect of the project to them. NSBCs are able to fulfil the role of waterproofing specialist as suggested by BS8102:2009 and we see that waterproofing contracts run more smoothly and have less issues where one of our NSBC contractors are also the waterproofing design specialist on the design team.