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Written by Warren Muschialli

Three Types of Waterproofing

Newton provide waterproofing products for all three types of waterproofing, defined within BS 8102:2022 as:

Type A – Barrier Protection

Type AThe 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

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

Type C – Drained Protection

Type CIf water passes through the structure, it is depressurised and collected by the internal Cavity Drain System and then safely removed from the building.

When Should A Combination Waterproofing System Be Specified?

Waterproofing Design Specialists are tasked to determine the use of combined protection in various forms where, in a single system:

  • the assessed risks are deemed to be high; or
  • the consequences of failure to achieve the required internal environment are deemed too high.

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

  • Type A, B & C
  • Type A & B
  • Type A & C
  • Type B & C or
  • Type A & A

Where a combination is being considered, systems should have different performance characteristics to mitigate the risk of failure due to a common cause. The compatibility of the different protection types should be assessed in order to minimise the risks and negate the need for remedial measures.

Usually a combination of two forms of waterproofing is adequate when designing a habitable space requiring a completely dry internal environment, defined as ‘Grade 3’ within BS 8102:2022.

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.

quotation marks“I have twenty years experience dealing with problems of moisture in buildings and have found Newton Waterproofing to be top of the tree when it comes to products, experience and technical understanding of structural waterproofing design and installation. The public and professionals alike can approach Newton’s with confidence.”James Hockey, Director – Trace Basements.


Example of a Typical Combination Waterproofing Design

Waterproofing Design

A typical combination waterproofing design showing the Newton CDM Cavity Drain System internally (Type C), Newton HydroBond System externally (Type A), and the Newton HydroTank System with waterbars and waterstops within the structure itself (Type B).


Newton highly recommends that installation is undertaken by a Newton Specialist Basement Contractor (NSBC).

NSBCs can provide a meaningful insured guarantee and take full design liability on the project, fulfilling the role of ‘Waterproofing Specialist’ as recommended by the BS 8102:2022 ‘Code of Practice for Protection of Below Ground Structures Against Water Ingress’. Please contact us directly to find out more about our contractors, or request a list of specialist contractors in your area.

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