The British Standard 8102:2009 ‘Code of Practice for the Protection of Structures Against Water from the Ground’ is the benchmark by which all below ground waterproofing projects in the UK are judged. Within the standard, a primary recommendation is that waterproofing designers always consider a combination of waterproofing systems for structures in situations where the likelihood of leakage is high or the consequences of leakage are unacceptable.
What is combined waterproofing?
When looking at combining waterproofing, there are three clear waterproofing categories that are defined by BS 8102:2009. Combined waterproofing is therefore the effective implementation of two or more of the following types:
The structure has no integral protection against water and relies on a membrane to be introduced internally or externally to prevent water ingress. Examples of external membranes include bonded sheet membranes, sodium bentonite matting and liquid applied coatings. Internally, similar approaches, such as cementitious coatings and bitumen or polymer-based liquids applied via spray, trowel, brush or roller, are employed in order to resist water ingress.
The structure is designed to be integrally waterproof and the primary resistance against water ingress. Such structures will be of high grade concrete and, in addition, will frequently utilise hydrophilic or metal waterbars to protect vulnerable construction joints, injection waterbars that have the capability to inject grout into porous and poorly compacted joints, and resins for the sealing of leaks post-construction.
It is accepted that water could enter the building and, therefore, an internal cavity drainage system of dimpled membranes are used to depressurise incoming water and harmlessly manage it away from the structure, either via gravity to open elevations or to be removed by mechanical means.
When are ‘combined’ waterproofing systems required?
The British Standard is also specific as to the three contexts in which a waterproofing designer should look to recommend a combined waterproofing approach. These can be summarised as:
1. When the likelihood of leakage is high.
2. When the consequences of leakage are unacceptable.
3. When additional vapour checks are necessary for a system where unacceptable water vapour transmission could otherwise occur.
However, the required internal environment also influences the potential necessity for a combined approach. As it happens, the British Standard also categorises internal environments into three Grades:
Grade 1 – Some seepage and damp patches tolerable, dependent upon intended use. Examples include car parks and non-electrical plant rooms.
Grade 2 – No water penetration, but damp areas are tolerable. Ventilation may be required. Examples include retail storage and workshops.
Grade 3 – No water penetration is acceptable. Ventilation, dehumidification or air conditioning is necessarily appropriate to the intended use. Examples include habitable spaces, offices and restaurants.
Whereas a combination of any two types of waterproofing is usually adequate for a Grade 3 environment, the safest combination will often include a type C system. The other systems are largely dictated by the type of structure being waterproofed.
Waterproofing to all Environmental Grades
Newton Waterproofing Systems, as a supplier of multiple waterproofing systems, can effectively combine its products as type A, B and C systems in order to fulfil the requirement of any environmental grade, regardless of the severity of the risk, the complexity of the project, or the clients’ exacting expectations.
This way, it is possible to ensure that professional specifiers and specialist waterproofing contractors have the products to successfully waterproof any project, new and existing, large or small, and from the smallest residential situation to the largest civil engineering and commercial developments.