Exterior Waterproofing for Retaining Walls

Retaining walls are an essential part of landscape design, especially when it comes to holding back soil and preventing erosion. However, without proper waterproofing, retaining walls can face serious damage due to water infiltration. Fortunately, there are specialized exterior waterproofing solutions that can help protect and preserve your retaining walls, no matter the size or material. In this article, we will explore these solutions in detail.

What Causes Retaining Wall Damage?

Retaining walls can face damage from a variety of factors, including:

  • Hydrostatic pressure: When water accumulates behind the wall, it creates pressure that can cause the wall to lean or crack.
  • Soil erosion: Rainwater, wind, and other natural elements can erode soil and create voids behind the wall, which can cause it to lose stability.
  • Freeze-thaw cycle: In colder regions, water freezes and expands in the winter, causing cracks and other types of damage to the wall.
  • Poor construction: If the wall was not designed or built properly, it may not be able to withstand the environmental stresses.

All of these factors can lead to the need for costly Repairs or even replacement of the retaining wall. Therefore, it is important to invest in a durable exterior waterproofing solution to protect against all these elements.

Types of Exterior Waterproofing Solutions

  1. Liquid sealants: Liquid sealants are coatings that are sprayed or painted onto the surface of the retaining wall. They provide a protective barrier against water infiltration, while also allowing the wall to breathe and preventing moisture buildup. Liquid sealants are a cost-effective option for smaller retaining walls, but they may not be as effective for larger walls or those facing heavy water pressure.

  2. Sheet membranes: Sheet membranes are large sheets of waterproof material (such as rubber, PVC, or modified bitumen) that are applied to the retaining wall. They create a physical barrier between the wall and the surrounding soil, preventing water from seeping through. Sheet membranes are more effective for larger retaining walls, especially those facing high water pressure, but they are also more expensive than liquid sealants.

  3. Drainage systems: Drainage systems work by diverting water away from the retaining wall and into a designated drain. They consist of a perforated pipe installed behind the wall and surrounded by gravel or other drainage material. Drainage systems are most effective for retaining walls built on sloping terrain, where water runoff is a concern.

Frequently Asked Questions

  1. Can I waterproof an existing retaining wall?

Yes, it is possible to waterproof an existing retaining wall using liquid sealants or sheet membranes. However, it is best to consult with a professional to determine the best approach for your specific situation.

  1. How often do I need to reapply exterior waterproofing?

The lifespan of an exterior waterproofing solution will depend on several factors, such as the material used, the intensity of weather conditions, and the level of Maintenance. As a general rule, it is recommended to reapply the waterproofing every 5-10 years.

  1. Can I install exterior waterproofing myself?

While it is possible to purchase liquid sealants or sheet membranes from a Home improvement store, it is recommended to seek the help of a professional Contractor for larger or more complex retaining walls. They have the necessary skills and equipment to ensure a long-lasting and effective application.


Retaining walls are important for maintaining the stability and aesthetics of your landscape. However, water infiltration can lead to serious damage and costly repairs. By investing in a specialized exterior waterproofing solution, you can protect and preserve your retaining walls for years to come. Whether you choose a liquid sealant, sheet membrane, or drainage system, consult with a professional to determine the best option for your specific needs and budget.

Cape Town Waterproofing

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