Types of Waterproofing: A Complete Guide to Modern Methods & Solutions

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Written by Warren Muschialli

Waterproofing is a cornerstone of modern below-ground construction, where water ingress can jeopardise both the integrity and usability of a building.

For architects, specifiers and developers, understanding the types of waterproofing available – and how to select the right system for each project – is critical.

This guide explores the full spectrum of waterproofing systems, highlighting Newton’s expertise and commitment to best practice as outlined in British Standard 8102:2022.

Why Is Waterproofing So Important in Modern Construction?

Effective waterproofing protects structures from groundwater ingress, dampness and hydrostatic pressure. Without robust waterproofing, basements, cellars, and other underground structures are vulnerable to water damage, mould, and even structural failure.

The right waterproofing solution not only ensures the safety and durability of your project but also safeguards your investment and reputation as a construction professional.

Understanding the Main Types of Waterproofing

British Standard 8102:2022, the code of practice for protection of below-ground structures against water ingress, defines three primary forms of structural waterproofing systems:

Let’s examine each type in detail, including their mechanisms, advantages, and best-use scenarios.

Type A: Barrier Protection

What is Type A Waterproofing?

Type A waterproofing, commonly referred to as barrier protection, involves applying a product that creates a barrier to the external facing surface or internal walls of a structure. This barrier prevents water ingress by resisting hydrostatic pressure and stopping moisture from penetrating the building fabric.

Type A systems can be applied both internally and externally to the structure and so the materials and performance requirements are very different, depending on where they are installed.

Typical Type A Systems – Internally Applied:

• Cementitious tanking slurries
• High-build cementitious renders

Typical Type A Systems – Externally Applied:

• Bituminous liquid applied coatings
• Pre- or post-applied sheet membranes
• High performance polymer liquid coatings

Where is Type A Waterproofing Typically Used?

• Retrofitting existing basements and cellars where an internal barrier system is required
• New build basements where external access is possible
• Structures where more than one Type of waterproofing is being combined to provide enhanced protection

Key Considerations:

• The quality of the workmanship is crucial – poor substrate preparation or product application can lead to failure.
• Type A systems are reliant on the continuity of the barrier – breaks in this continuity provide opportunities for water to breach the barrier
• Service penetrations, construction joints and changes in direction all require particular attention and careful detailing

Our Type A Solutions:

HydroBond System

A range of advanced barrier membranes and pastes for external application to the outside of the structure.

HydroCoat System

Cementitious renders and slurries, designed for internal, tanking applications. These products are suitable for use above floor slabs, and to the inside of retaining walls, providing robust resistance to groundwater.

Type B: Structurally Integral Protection

What is Type B Waterproofing?

Type B waterproofing, or structurally integral protection, is achieved by designing the structure itself to be water resistant. This is typically done using reinforced concrete that has been correctly designed and installed to comply with BS EN 1992, Eurocode 2 on the Design of concrete structures. However, even the best placed concrete has gaps at the construction joints and where service penetrations enter the structure. It is therefore essential to select and specify appropriate products to seal all joints and penetrations and ensure that the external shell of the structure forms a continuous barrier against water.

Typical Type B Systems:

• Construction joint waterbars and water stops
• Injection resin waterbar systems
• Seals for service penetrations of cables and pipes, both inside and outside of the penetrating sleeve
• Sealing of tie-bolt holes left behind by concrete formwork

Where is Type B Waterproofing Typically Used?

• New build basements and below-ground or water-retaining concrete structures such as tunnels, car parks, reservoirs, holding tanks, and more
• Any project where the structure is designed from the outset to resist water ingress

Key Considerations:

• The success of Type B systems depends on the design, quality of the concrete, workmanship, and detailing.
• Joints, cracks, or service penetrations require particular attention and, despite being the areas most likely to leak, are often overlooked.
• May be used in combination with other forms of waterproofing for added resilience.

Our Type B Solutions:

HydroTank System

We supply a range of Type B waterproofing products, including waterbars, waterstops, flanges, tie-bolt hole and service entry sealing systems. These ensure that the external shell of new build basements and other underground structures remain watertight.

Type C: Drained Protection

What is Type C Waterproofing?

Type C waterproofing, or drained protection, is a modern, highly effective method that manages water ingress by allowing it to enter into a planned and controlled cavity, where it is then safely removed from the structure. This is achieved using a cavity drain membrane system comprising of wall and floor membranes, drainage channels, and a designated safe point of disposal such as a sump pump system.

How Does a Type C System Work?

• A cavity drain membrane system is installed on the internal walls and floor of the structure, creating a void between the structure and the internal finishes.
• Any water that penetrates the external shell is collected by these cavities.
• Designed drainage channels direct water to a sump pump or, where safe to do so, to passive, gravity drainage.
• The water is then pumped or drained away from the building, preventing water from contacting wall and floor finishes and maintaining a completely dry internal space.

Where is Type C Waterproofing Typically Used?

• Both new-build and retrofit basement waterproofing where the new internal environment needs to be completely dry
• Projects where the risk of water ingress requires a robust and comprehensive system to ensure the long-term protection of the structure
• Situations where ongoing maintenance is manageable to ensure the for long-term reliability of the Type C system

Key Considerations:

• Maintenance is essential to prevent blockages in drainage channels and ensure long-term performance, and to comply with British Standard 8102:2022
• Backup pumps, batteries and control systems should be specified to guarantee the continued viability of the system even during power outages
• Type C waterproofing is the most suitable waterproofing solution for historic and listed properties, due to its limited impact on the existing structure and its ‘reversibility’

Our Type C Solutions:

The BBA-certified CDM System is a leading Type C waterproofing solution, featuring high-performance cavity drain membranes, drainage channels, and sump pump systems. The system is suitable for use in any below-ground waterproofing scenario, including listed and historic properties, and is designed for rapid installation with minimal preparation.

Comparing the Main Types of Waterproofing

What Is the Role of British Standard 8102:2022 in Waterproofing Design?

BS 8102:2022 is the definitive code of practice for protecting below-ground structures against water ingress in the UK. It sets out the requirements for waterproofing design, specifying that a waterproofing specialist should be included in the design team from the earliest stages.

The standard also requires that Type C systems, are accessible for maintenance and that a combination of systems may be necessary to achieve the required level of protection.

Combination Waterproofing Systems

For many projects, particularly those with challenging ground conditions or critical usage requirements, a combination of waterproofing methods provides the most robust solution. For example, combining Type B (integral) and Type C (drained) systems can offer both structural resistance and managed drainage, significantly reducing the risk of water ingress even in the event where water manages to pass through the structure.

Our design team frequently specifies combined systems, tailored to the unique requirements of each project and compliant with BS 8102:2022.

The Importance of Quality, Design and Maintenance

The success of any waterproofing system depends on the quality of the workmanship, the appropriateness of the chosen method, and ongoing maintenance. Poor preparation, inadequate detailing, or lack of maintenance, among other things, can lead to system failure.

Engaging a waterproofing specialist from the earliest design stages ensures compliance with the code of practice and delivers a robust, long-lasting solution.

Why Choose Newton Waterproofing?

Founded in 1848, we are the UK’s oldest and largest independent designer and supplier of guaranteed basement waterproofing systems. Our services include:

• A nationwide network of Newton Specialist Basement Contractors for fully guaranteed installations and maintenance
• Bespoke design service, backed by Professional Indemnity Insurance
• RIBA-approved CPD seminars for architects and specifiers
• BBA-certified products and systems
• Technical support and expert advice for projects of any size

For expert advice on selecting and specifying the right types of waterproofing for your next project, contact our technical team today. Benefit from our unrivalled experience, comprehensive product range, and commitment to delivering robust, compliant, and fully guaranteed waterproofing solutions for every application.