Installing Waterproofing for Retaining Walls

Retaining walls are an essential element in landscaping, providing structure and support to uneven terrain. However, these walls are constantly subjected to moisture, which can cause serious damage over time. Waterproofing is crucial to prevent water infiltration and protect the integrity of the retaining walls. In this article, we will delve into the installation techniques for waterproofing retaining walls, ensuring their longevity and functionality.

Why is Waterproofing Important for Retaining Walls?

Retaining walls are typically built to retain soil and prevent erosion, creating level surfaces and preventing slope failure. However, water can seep through the soil and exert pressure against the walls, compromising their structural integrity. By waterproofing the retaining walls, you create a barrier to prevent water penetration, reducing the risk of damage and prolonging their lifespan.

Common Waterproofing Techniques for Retaining Walls

There are various techniques available for waterproofing retaining walls, depending on the specific requirements and conditions. Here are some of the commonly used methods:

  1. Membrane Waterproofing: This technique involves the application of a waterproofing membrane directly onto the retaining wall surface. The membrane can be made of materials such as bituminous sheet, rubberized asphalt, or polyurethane. It forms a barrier that prevents water from seeping into the wall structure. Membrane waterproofing is a popular choice due to its effectiveness and versatility.

  2. Liquid Applied Waterproofing: In this method, a liquid waterproofing material is applied directly onto the retaining wall surface. It can be sprayed or rolled on, creating a seamless protective barrier. Liquid applied waterproofing is known for its ability to adhere to different surfaces and accommodate irregular shapes, making it ideal for retaining walls with complex designs.

  3. Crystalline Waterproofing: Crystalline waterproofing is a unique approach that utilizes chemicals that react with moisture to form insoluble crystals. These crystals penetrate the concrete structure, filling pores, capillaries, and hairline cracks, thereby blocking water passage. This method enhances the long-term durability of the retaining walls by providing self-sealing capabilities.

  4. Drainage Systems: Installing a proper drainage system can significantly contribute to the effectiveness of waterproofing. The system helps divert water away from the retaining walls, preventing it from accumulating and exerting excess pressure. Techniques such as French drains, weep holes, and gravel backfill are commonly used to optimize the drainage capabilities of retaining walls.

  5. Cementitious Waterproofing: Cementitious waterproofing involves the application of a cement-based coating or paint onto the retaining wall surface. This coating becomes an integral part of the wall, providing protection against water penetration. Cementitious waterproofing is known for its durability and resistance to harsh weather conditions.

How to Install Waterproofing for Retaining Walls

Installing waterproofing for retaining walls requires careful planning and execution. Here is a step-by-step guide to the installation process:

  1. Surface Preparation: Before applying the waterproofing material, it is essential to clean the retaining wall surface thoroughly. Remove any loose debris, dirt, or contaminants that could hinder the adhesion of the waterproofing material. Repair any visible cracks or damages on the wall surface.

  2. Selection of Waterproofing Material: Choose the appropriate waterproofing material based on the specific requirements of the retaining wall. Consider factors such as wall material, design, climatic conditions, and budget.

  3. Application of Waterproofing Membrane: If using a membrane-based waterproofing system, roll out or brush the membrane onto the retaining wall surface, ensuring complete coverage. Pay attention to corners, joints, and any potential weak points. Use a primer if required for improved adhesion.

  4. Application of Liquid Waterproofing: For liquid applied waterproofing, follow the manufacturer’s instructions for application. Use a brush, roller, or sprayer to evenly coat the retaining wall surface. Apply multiple layers if necessary, allowing sufficient drying time between each coat.

  5. Crystalline Waterproofing Application: If opting for crystalline waterproofing, mix the crystalline material with water to form a slurry. Apply the slurry generously onto the retaining wall surface, ensuring it penetrates deep into the concrete. Allow it to dry and cure as recommended.

  6. Installation of Drainage System: Integrate the appropriate drainage system into the retaining wall design. This may involve installing French drains, weep holes, or providing adequate gravel backfill behind the wall. Ensure proper functioning of the drainage system to prevent water accumulation.

  7. Finishing Touches: Once the waterproofing system is in place, make any necessary finishing touches. This may include backfilling soil, adding decorative features, or applying a protective coating for enhanced durability.


Q: How long does waterproofing for retaining walls last?

A: The longevity of waterproofing for retaining walls depends on various factors such as the quality of materials used, installation techniques, and Maintenance. With proper installation and regular inspections, waterproofing systems can last for several decades.

Q: Can I waterproof an existing retaining wall?

A: Yes, it is possible to waterproof an existing retaining wall. However, the process may be more challenging and may require specialized techniques depending on the wall’s condition and materials. Consult with a professional for the best approach.

Q: Is professional installation necessary for waterproofing retaining walls?

A: While DIY waterproofing is possible, professional installation is recommended for optimal results. Experts have the knowledge, experience, and access to high-quality materials to ensure effective waterproofing and long-term durability.


Waterproofing is a critical aspect of retaining wall construction, protecting against water infiltration and ensuring their long-term stability. By employing techniques such as membrane waterproofing, liquid applied waterproofing, crystalline waterproofing, and incorporating drainage systems, retaining walls can be safeguarded from moisture-related damages. With proper installation and maintenance, waterproofed retaining walls can provide reliable support and enhance the aesthetics of any landscape.

Cape Town Waterproofing

Leave a Comment

Your email address will not be published. Required fields are marked *

Open chat
Need help?
Hi there,
Can I offer you a FREE no obligation quote?