British Standard 8102 is a global Code of Practice that gives recommendations and guidance on ways to deal with and prevent the entry of water from surrounding ground into a structure below ground level.
The standard covers waterproofing barrier materials applied to the structure; drained cavity construction; structurally integral watertight construction; alongside the evaluation of groundwater conditions, risk assessment and options for drainage outside of the structure. Essentially, it takes you through the specification, design and construction principles of basement waterproofing systems.
Recently, there have been many updates to BS 8102, which newer materials and practices. It has also been extended to cover a wider range of structures that are becoming increasingly popular. In this blog, Mike Jones, National Waterproofing Manager, explains the key points and provides a summary of the changes.
A notable change in BS 8102:2022 – compared to BS 8102:2009 – is the expanded scope to include better coverage of below ground structures such as tunnels.
This updated version now takes into account the risk of moisture and water entering the structure through doors, light wells and air bricks. It means that the overall design of a structure should include not only below ground waterproofing, but wider conditions too, as they are intertwined with each other.
Further changes can be seen in the additional details within the design considerations, for the expected highest level of the water table, soil characteristics and the intended use of the building once finished.
The standard also recommends that a waterproofing design specialist should be consulted at the earliest stage of a project, so that they can make any necessary approvals on amendments that will affect the overall waterproof design.
Changes to the grades of waterproofing
One of the main changes that affects the design and specification of a waterproofing system is the grading of waterproofing. The 2009 version of the standard had three gradings of waterproofing, from some allowance of seepage to a full and comprehensive waterproofing system, and consideration for the ventilation of habitable spaces.
Grade one in BS8102:2022 has now been subdivided into two new categories, Grade 1A and 1B:
- Grade 1A: Seepage (slow transmission of water) and damp areas (slightly wet but no transmission) from both internal and external sources are tolerable, if this does not impact the proposed use of the space. This can be described as a wet environment where free water can enter.
- Grade 1B: No seepage (slow transmission of water), but damp areas (slightly wet but no transmission) from internal and external sources are tolerable. This means that free water is not allowed to enter but damp patches may occur.
There are a variety of other changes that have been made to the standard. A key change from BS8102: 2009 is the emphasis placed on ensuring that all waterproofing designs should be continuous with the damp proof course level or taken to 150mm above the external ground level.
A section on buried decks below ground level has also been added, which notes the importance of providing waterproofing protection to these, and how they should differ from roofs above the ground level.
In regards to servicing and maintenance of Type C Cavity Drainage Membranes, BS8102:2022 states that these should now have a maintenance schedule, with the first service inspection at handover stage and these details ideally recorded to prove the system is working correctly.
This is a short summary of BS8102: 2022t and the amendments that have been made. If you have any questions or queries about the new changes, or waterproofing in general, please get in touch.
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