waterproofing failures

The cost and inconvenience of returning to a site because of the ingress of water due to a failed waterproofing installation is an unwelcome event for any project. 

Walls & Roofs spoke to the industry leaders in waterproofing and asked for the top five most common causes of waterproofing failures, in their experience.  

Incorrect system selection 

 At the outset, it’s crucial to conduct a thorough risk and reliability assessment, considering environmental variables and on-site conditions such as the foundation depth, steel congestion and existing systems. The quality and suitability of the chosen waterproofing system are paramount for preserving both the structural integrity and aesthetic appeal of a building over time. 

Miscalculating the compatibility of substrates or neglecting factors such as primer compatibility can lead to debonding and eventual system failure. Wayne Smithers, technical service manager of Sika, explains: “A reliable waterproofing solution not only safeguards the building but also substantially reduces the total cost of ownership (TCO) over the concrete structure’s service life.” 

waterproofing failures

Sika Sarnafil® PVC (polyvinyl chloride) sheet membranes are root-resistant and well suited to green roofing.

Inadequate substrate preparation 

Failures in waterproofing systems can arise from poor preparation of the substrate. Substrate preparation entails ensuring that the surface slated for waterproofing is thoroughly cleaned, dried and devoid of any contaminants or flaws that may compromise the adhesion of waterproofing materials. 

Inadequate substrate preparation can lead to improper bonding between the waterproofing membrane and the substrate, resulting in leaks and water ingress.  

Common issues stemming from poor substrate preparation include:  

  • Incomplete removal of dirt, oil or other surface contaminants. 
  • Insufficient roughening or profiling of the substrate to enhance adhesion.  
  • Failure to address cracks or defects in the substrate before applying waterproofing materials.  

Incorrect waterproofing application methods 

Ensuring correct installation is crucial for the effectiveness of waterproofing measures. When the waterproofing system is not applied in accordance with the manufacturer’s guidelines or if it sustains damage during construction, this can result in moisture penetration and associated issues. 

Common application issues include: 

Applying waterproofing onto:  
  • Green/uncured substrates. 
  • High moisture content substrates, thereby trapping moisture below the waterproofing system.  
  • Contaminated substrates, which usually causes delamination. 
Insufficient bedding of membranes in 90-degree corners. 
Not allowing the waterproofing to cure completely before tiling or applying other final floor coverings. 
Incorrect installation or an installation by inexperienced applicators. 
waterproofing failures

TAL Superflex Fibre 1K is a ready-to-use, fibre-enriched, acrylic-based liquid waterproofing compound specifically designed to be fully compatible with cement-based tile adhesives.

Common causes of damage include early trafficking by other trades or construction traffic whilst the waterproofing system is not yet covered with a floor finish, such as tiles. “Installation of the final floor covering can also damage the waterproofing, i.e., damage caused by sharp corners of tiles or whilst cleaning tile joints,” says Obert Rukato, technical executive at TAL. 

 Structural movement 

Structural shifts may trigger the formation of cracks in the foundation or walls of a building, potentially undermining the efficacy of the waterproofing system. With time, structural deterioration can lead to the emergence of tensile cracks, facilitating water penetration into the concrete structure. The degree of water ingress is influenced by variables including the crack width, length and hydraulic gradient. 

 Inadequate drainage 

Insufficient drainage can result in water pooling around the building, exerting hydrostatic pressure on the waterproofing materials and compromising their integrity. This accumulation of water may eventually lead to leaks, water damage and the proliferation of mould and mildew within the structure. Well-designed drainage systems are engineered to collect and divert water away from the building, preventing it from infiltrating vulnerable areas. 

Any blockage or damage to the drainage system can hinder this process, allowing water to seep into the building and heightening the risk of waterproofing failure. Ensuring the proper design, installation and upkeep of drainage systems is crucial for maintaining the long-term performance and efficacy of waterproofing measures. 

Waterproofing innovations for Africa 

Contributors to this article share some of the waterproofing systems and innovations available for modern buildings in Africa: 

Basements: The SikaProof® A+ System is a high-performance and durable fully bonded sheet membrane system for damp and waterproofing in basements and below ground structures. The unique A+ technology creates a permanent mechanical and chemical bond between the membrane and concrete. Combined with a highly flexible and durable FPO waterproofing layer, it ensures a long-lasting water and gas barrier. 

 Whether applied pre- or post-construction, it forms a secure bond with reinforced concrete structures, effectively blocking lateral water migration. Versatile and reliable, it is ideal for a wide range of projects – from residential and commercial basements to large-scale infrastructure ventures such as cut-and-cover tunnels and station boxes.

Green roofing: Sika Sarnafil® PVC (polyvinyl chloride) sheet membranes have been used internationally for over 50 years. Engineered with glass-fibre reinforcement and crafted in Switzerland, this membrane is versatile across various roof designs and structures in both new constructions and renovations. It is specifically designed for subgrade environments to maintain watertight integrity even in the harshest conditions, enduring constant dampness, ponding water and extreme pH levels. 

The system is inherently resistant to roots, algae and fungal organisms. This not only ensures longevity but also makes it an ideal solution for green roof systems, eliminating the need for additional root barriers.  


Sikalastic®-625 is an exceptionally efficient single-component, cold-applied, moisture-triggered polyurethane membrane engineered for roofing applications in both new constructions and renovation projects. A notable advantage is its ability to mitigate the urban heat island effect, owing to its reflective nature. 

These roofs reflect more sunlight and absorb less heat compared to conventional roofing materials, thereby diminishing the urban heat island effect and enhancing the overall air quality. Once fully cured, the system forms a seamless, robust and weather-resistant waterproofing solution suitable for exposed roof areas. 


TAL Superflex Fibre 1K is a ready-to-use, fibre-enriched, acrylic-based liquid waterproofing compound specifically designed to be fully compatible with cement-based tile adhesives. The formulation provides a flexible waterproofing system that eliminates the need for reinforcing membranes in most applications, and it is ideal for installations where no significant building movement will take place or where the use of a membrane-reinforced system is impractical. 

Applied using a short pile (mohair) roller, it can accommodate normal structural movement in the background and is ideal for waterproofing shower recesses, internal wet areas, external balconies and terraces, planter boxes, roof slabs and parapet walls prior to tiling. 


Issue: Waterproofing failures leading to water ingress on projects. 

Solution: Avoid these top five causes of waterproofing failures for a successful waterproofing installation. 


Full thanks and acknowledgement go to www.sika.com and www.tal.co.za for the information in this article. 

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