London Waterproofing Solutions Ltd
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London Waterproofing Solutions Ltd

BS8102:2009 & Basement Waterproofing

BS8102:2009 is the Code of practice for protection of below ground structures against water from the ground. This document provides a set of guidelines that should be followed when designing a waterproofing system for any below ground structure, including basements, vaults, cellars and car parks.

Whether your project is a new build, renovation of an existing property or you simply want to ensure your Victorian basement is dry enough to use for additional storage, the design philosophy of BS8102 should be applied. One important point made in this document in regard to basement waterproofing design is in paragraph 4.2, where it states “A waterproofing specialist should be included as part of the design team so that an integrated waterproofing solution is created”. A waterproofing specialist will generally hold a CSSW qualification, (Certificated Surveyor in Structural Waterproofing) as proof of their expertise. It is important that any basement waterproofing project has a CSSW designer involved to ensure the system is designed and installed correctly.

Design Philosophy of BS8102:2009

This code of practice includes a design process that must be applied when it comes to designing a suitable waterproofing system. For new developments, information such as soil reports, method of construction, nearby watercourses and the water table classification should be taken into account.

Any waterproofing design should take into account what defects may occur with the selected system and how the system can be maintained or accessed for remedial treatment if necessary.

For new builds, often two forms of waterproofing will be required by the warranty provider and in some cases this will may apply to renovation projects too. It is important to check this at the design stage so these can be included with the design.

Different Types of Waterproofing

There are three common types of waterproofing available within BS8102.

  1. Type A – Barrier system and can be applied internally or externally. The products used can include cementitious renders, bentonite clay membrane, bonded sheet membranes or liquid applied tanking membranes
  2. Type B – Structurally integral protection, typically the use of waterproof concrete to form the structure.
  3. Type C – Drained protection, this consists of a drained cavity typically installed with a sump pump system to discharge ground water.

When deciding which waterproofing system is to be used, Table 1 in BS8102 gives us guidance on the types of system that can be used depending on the water table classification.

The water table is classified as either low, variable or high. A high water table is understood to mean where the water is permanently above the underside of the basement slab. This can happen as a result of the true water table, or due to a perched water table. A perched water table occurs in poor draining soils, such as clay based soils and is often seen during periods of heavy rainfall.

Table 1 indicates only two types of waterproofing are acceptable in all water table conditions, Type B reinforced concrete wall to BS EN 1992 and a Type C cavity drain system.

 

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