Waterproofing is a critical step in protecting buildings from water damage, but the type of waterproofing system chosen depends on the specific conditions and needs of the structure. One of the fundamental decisions in waterproofing is whether to apply a negative-side or positive-side waterproofing system. In this article, we will explore the differences between these two approaches and help you understand which one might be the best for your project.

1. What is Positive-Side Waterproofing?

Positive-side waterproofing is the most common and widely used waterproofing method. It involves applying waterproofing materials to the exterior side of a structure, preventing water from entering the building in the first place. This is typically done during construction, where the foundation or walls are coated with waterproofing products such as membranes, coatings, or sealants.

How Positive-Side Waterproofing Works:

Positive-side waterproofing creates a barrier between the structure and the surrounding water. By placing the waterproofing layer on the outside, the material is exposed to the elements and the hydrostatic pressure of water. It prevents water from penetrating the structure’s surface by stopping it before it can reach the walls or foundation. Commonly used materials for positive-side waterproofing include liquid-applied membranes, sheet membranes, and cementitious coatings.

2. What is Negative-Side Waterproofing?

Negative-side waterproofing, on the other hand, involves applying the waterproofing layer to the interior side of a structure, typically after construction is complete. This approach is often used when access to the exterior side of the foundation or walls is not possible or practical. It addresses water penetration that has already occurred and provides a way to stop moisture from entering the interior space.

How Negative-Side Waterproofing Works:

In negative-side waterproofing, the waterproofing material is applied to the interior surface of walls or floors. This system essentially prevents water from traveling further into the structure after it has already infiltrated the walls. The waterproofing layer is applied directly onto the affected surface, preventing moisture from entering living or storage spaces. Common materials used in negative-side waterproofing include coatings, membranes, and cement-based products.

3. Key Differences Between Positive-Side and Negative-Side Waterproofing

Although both positive-side and negative-side waterproofing serve the same purpose—preventing water infiltration—there are several important differences between the two methods.

Location of Application:

• Positive-Side Waterproofing: Applied to the exterior of a structure, such as the foundation or exterior walls, during the construction phase.
• Negative-Side Waterproofing: Applied to the interior side of the walls or floor after construction, usually when access to the exterior is limited or unavailable.

Pressure Considerations:

• Positive-Side Waterproofing: Works under the pressure of water pushing from the outside, such as groundwater or rainwater, and prevents it from entering the building.
• Negative-Side Waterproofing: Primarily deals with water that has already entered the structure, providing a barrier against further moisture intrusion.

Application Complexity:

• Positive-Side Waterproofing: Easier to apply during the construction phase and can cover a larger surface area with fewer complications.
• Negative-Side Waterproofing: Often requires more specialized techniques, particularly when applied to existing buildings. It can also be more difficult to achieve complete waterproofing on surfaces that have already been compromised.

Effectiveness Over Time:

• Positive-Side Waterproofing: Typically offers a longer-lasting solution, as it prevents water from even reaching the structure.
• Negative-Side Waterproofing: While effective in stopping ongoing water infiltration, it is not as durable as positive-side waterproofing because the waterproofing layer is exposed to potential damage from the inside (e.g., cracking or wear over time).

4. When to Use Positive-Side Waterproofing

Positive-side waterproofing is generally the preferred method for new construction projects, as it is easier to implement and provides long-term protection against water penetration. It is especially effective for:

• New foundations
• Concrete slab floors
• Underground structures

This approach ensures that water is stopped at the source and does not infiltrate the structure, preventing costly repairs or interior damage caused by water.

Benefits of Positive-Side Waterproofing:

• Prevents water from reaching the structure
• Provides more durable protection
• Ideal for new builds or projects where the exterior is easily accessible
• Can be applied during the construction phase for cost and time savings

5. When to Use Negative-Side Waterproofing

Negative-side waterproofing is most commonly used in existing structures where it is difficult or impossible to apply positive-side waterproofing. It’s particularly useful in situations where:

• The exterior surface is already inaccessible (e.g., adjacent to another building, street, or other obstacles)
• Water has already penetrated the structure, and interior waterproofing is required to stop it from spreading
• The building has already experienced water damage that needs to be addressed

Benefits of Negative-Side Waterproofing:

• Can be applied to existing structures
• Provides effective moisture control in basement or underground areas
• Easier to apply when exterior access is limited

6. Combining Both Systems for Maximum Protection

In some cases, combining both positive-side and negative-side waterproofing systems can offer the best protection. This method involves applying a positive-side system on the exterior during the construction phase and a negative-side system to the interior if water infiltration has occurred over time.

Benefits of Combining Systems:

• Dual protection from both external and internal water sources
• Increased overall effectiveness in high-risk areas (e.g., basements, underground structures)
• Enhanced durability and long-term moisture management

Our Trusted Partners

Apolodor LTD exclusively partners with leading manufacturers such as Sika, Ronacrete, and Fosroc to supply the finest materials available. By sourcing products from these renowned brands, we can ensure that every project benefits from the highest standards of quality and performance. These partnerships are the foundation of our commitment to delivering construction solutions that are built to last and perform at their best for years to come.

Conclusion

Choosing between positive-side and negative-side waterproofing depends on the specific needs and conditions of your building. In the context of Waterproofing solutions in the United Kingdom, positive-side waterproofing is typically the most effective and long-lasting option for new construction, while negative-side waterproofing offers a viable solution for existing structures with limited exterior access or when water infiltration has already occurred. In some cases, combining both systems can provide the highest level of protection for your property.

By understanding the differences between these two approaches, you can make an informed decision about which waterproofing system will best suit your needs and ensure the long-term protection of your building from water damage.