Solutions / Combination Waterproofing Explained

Combination Waterproofing Explained

When tasked to waterproof retaining structures in accordance with BS 8102:2009, professional waterproofing designers should consider using more than one type of waterproofing to provide enhanced protection of the structure and to achieve the necessary environmental grade. Newton provide waterproofing products for all three types of waterproofing as defined within BS 8102:2009:
  • Type A – Barrier Protection 

    The Structure has no integral protection against water and relies on a membrane to be introduced internally or externally to prevent the ingress of water into the inner building fabric.

  • Type B – Integral Protection

    The structure itself is constructed to be integrally waterproof and the primary resistance against water ingress. 

  • Type C – Drained Protection

    It is accepted that water could enter the building and an internal cavity is provided to depressurise and manage the water. 

When Should A Combination Waterproofing System Be Specified?
  • Waterproofing Design Specialists are tasked to recommend a “combined“ waterproofing system approach particularly where:

    1. The likelihood of leakage is high 

    2. The consequences of leakage are unacceptable 

    3. Additional vapour checks are necessary for a system where unacceptable water vapour transmission could otherwise occur

  • With this in mind, the possible combinations of waterproofing are 

    Type A, B & C

    Type A & B

    Type A & C or 

    Type B & C

Usually a combination of 2 forms of waterproofing is adequate when designing a habitable space requiring a completely dry internal environment, defined as ‘Grade 3’ within BS 8102:2009. Whichever combination of waterproofing is chosen to achieve the Grade 3 environment, in most cases the safest combination will include a Type C internal cavity drain membrane system as one of the forms of waterproofing. The choice of the other system is largely dictated by the type of structure.

Example of a Typical Combination Waterproofing Design

A typical combination waterproofing design showing Newton System 500 Cavity Drain System internally (Type C), Newton System 400 membrane externally (Type A), and Newton System 300 waterbars and waterstops within the structure itself (Type B) 

Featured Products 
  • Newton 403 HydroBond Waterproofing Membrane

    Type A Protection - A high performance, pre-applied self-healing sheet membrane that features a locking fleece and a polymer hydrophilic coating. The 403 HydroBond®-GB variant also provides resistance to radon, carbon dioxide and hydrocarbon gases. 

  • Newton 315 Polymer-Waterbar

    Type B Protection - Hydrophilic waterbar which swells on contact with water in order to seal either non-compressed joints such as raft to raft, or compressed joints such as at the kicker.

  • Newton System 500 Cavity Drain Protection 

    Type C Protection - Maintainable waterproofing solution, including a range of cavity drain membranes, pumps, pumping control panels and drainage provision. Where possible a Type C internal cavity drain system should be used as part of a combination waterproofing system, as it is the safest form of waterproofing. 

Typical Specifications
  • Newton Systems 400, 300 and 500 are employed to provide Type A, B & C waterproofing protection

  • A typical combination waterproofing design showing Newton System 500 Cavity Drain System internally (Type C), Newton System 400 membrane externally (Type A) & Newton System 300 for integral waterproofing details (Type B) 

“Due to the quality of finish and goods to reside within a large basement project we were working on, the waterproofing scheme was designed with a combination of Type A and Type C systems for maximum protection. It was therefore essential that the product quality reflected the design effort. We were pleased to install Newton products throughout to help maintain the highest of standards due to their forward thinking, reliable technical support and complete range of quality waterproofing products.”-  

Nick Wells, Advanced Basements (Christian Dior Store, Central London)


Newton highly recommend that installation is undertaken by a Newton Specialist Basement Contractor (NSBC). NSBCs can provide a substantial insured guarantee and take full design liability on the project, fulfilling the role of ‘Waterproofing Specialist’ as recommended by the BS 8102:2009 ‘Code of Practice for Protection of Below Ground Structures Against Water From The Ground’. Please contact us for a list of NSBCs in your area.

Further Information

For any further information about Type C waterproofing systems, or for any technical advice about your waterproofing project please contact us please contact us on 01732 360 095 or