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Written by Warren Muschialli

When it comes to maintaining a dry and habitable environment within below-ground buildings, waterproofing is a critical consideration. A cavity drain system is an ingenious solution that effectively isolates the internal wall and floor finishes from water ingress and dampness.

In this article, we explore what a cavity drain system is and highlight the innovative range of cavity drain products offered by Newton Waterproofing.

What is a Cavity Drain System?

A cavity drain system is a type of waterproofing solution used in below-ground structures, such as basements, cellars, and other commercial and residential spaces.

Unlike traditional waterproofing methods that attempt to block water from entering the structure, a cavity drain system diverts, collects and manages water entering the structure and then safely removes the groundwater from the building.

How Does a Cavity Drain System Work?

The cavity drain system consists of three primary components:

  • Cavity Drain Membrane – High-density polyethylene (HDPE) membranes feature stud-like protrusions that create a cavity between the membrane and the walls and floor. The cavity membrane effectively forms depressurisation voids that divert any water that penetrates through the structure to the drainage channels.
  • Drainage Channels – These are placed at the base of the wall or above weaknesses in the structure, such as construction joints, and create larger voids to collect water diverted by the Cavity Drain Membranes as well as directly receiving water as it passes through the structure. The drainage channels also act as pathways for the water to flow towards designated discharge points.
  • Sump and Pump System – Where water cannot safely leave the building by gravity, the collected water is channelled to a sump, where a dual pumping system efficiently expels the water away from the structure.

What Are the Benefits of a Cavity Drain System?

Installation of Newton cavity drain membrane to listed vaults

  • Highly Effective – Cavity drain systems are highly reliable and efficient in managing water ingress and are the most effective method of providing a consistently dry and habitable space.
  • Minimal Surface Preparation – Unlike traditional tanking systems that require extensive surface preparation, cavity drain systems can be installed on with little or no surface preparation, reducing installation time and potential damage to the building fabric.
  • Reduced Structural Stress – Because the cavity drain system is not resisting ground water pressure, it does not unduly influence the structure in the same way as a tanking system, where the effective waterproofing barrier results in an increased hydrostatic pressure bearing against the structure which may lead to potential structural damage.
  • Insurance-Friendly – Because cavity drain systems are so safe, many waterproofing contractors and their insurers will not provide installation guarantees unless they are included as part of the overall waterproofing strategy.

Newton CDM System


When it comes to achieving a completely dry internal environment in below-ground structures, the Newton CDM System is a comprehensive Type C waterproofing solution.

Whether for new-build basements or refurbishment projects, this system offers a maintainable and reliable approach to basement waterproofing, by incorporating a range of BBA approved cavity drain membranes, drainage channels, sump chambers, pumps, and cutting-edge control and telemetry systems.

Type C Waterproofing

British Standard 8102:2022 defines three forms of waterproofing. Type C (drained) protection is defined as “protection against water ingress into usable spaces provided by the incorporation of an appropriate internal water management system”. This works by ensuring that water is received by the voids and air spaces that are cleverly created by the cavity drain system on the internal side of the structure. This depressurises the incoming water, at which point it is safely removed from the property. The Newton CDM System exemplifies this approach, drawing on decades of waterproofing expertise and incorporating industry-leading products.

Third Party Certification: BBA Approved Cavity Drain Membranes

The Newton CDM waterproofing system boasts an array of BBA certified cavity drain membranes, including 100% recycled options, setting a high standard for quality and reliability. Paired with the BaseDrain drainage system, bespoke sump and pump configurations, backup systems, telemetry, and ancillary options, the Newton CDM System stands as the most trustworthy and maintainable waterproofing solution for any habitable space below ground.

Combining Strengths: Complementary Waterproofing Solutions

For even greater waterproofing protection, British Standard 8102:2022 recommends combining two or more types of waterproofing. The versatile Newton CDM System can be seamlessly combined with our Type A solutions, Newton HydroBond or Newton HydroCoat, and/or our Type B solution, Newton HydroTank.

The Newton Specialist Contractor Network: Your Waterproofing Partners

Newton are proud to partner with a nationwide network of trained and qualified Newton Specialist Basement Contractors (NSBCs) who are professional designers and installers of our full range of waterproofing systems, and carry their own professional indemnity insurance liability cover.

NSBCs collaborate closely with our own dedicated waterproofing specialists, including our in-house teams of CSSW qualified designers and experienced site support managers. This combination makes the Newton Specialist Contractor network the key to your waterproofing project success, with the ability to turn projects around quickly, from initial enquiry through to comprehensive design and successful installation.

Embrace Excellence with the Newton CDM System

Cavity Drain Waterproofing

The Newton CDM System sets the standard for comprehensive waterproofing solutions in below-ground structures. With a focus on reliability, maintainability, and responsible sourcing, this Type C waterproofing system, complemented by its BBA approved cavity drain membranes and versatile integration options, offers unparalleled protection for any habitable space below ground. When it comes to safeguarding your building from water ingress, partnering with Newton Waterproofing and embracing the Newton CDM System is the best choice you can make.

How Can Newton Waterproofing Help You?

We are dedicated to providing high-quality waterproofing services throughout the UK, and our team of experienced professionals has the expertise to tackle even the most challenging projects. We adhere to industry standards and use proven methods, ensuring long-lasting results and peace of mind, so contact us today to get started.


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