Negative side waterproofing refers to the application of waterproofing materials on the interior surface of basement walls. This method aims to create a barrier that prevents moisture or water vapor from penetrating the basement walls.

Selecting Materials for Negative Side Waterproofing

The selection of waterproofing materials is critical for the success of negative side waterproofing. Common materials include waterproofing coatings, sealants, and membranes. These substances can withstand the challenges posed by interior moisture, providing a barrier that prevents water in liquid or vapor form from entering the occupied space.

Challenges and Limitations of Negative Side Waterproofing

Hydrostatic Pressure and its Impact

One of the primary challenges associated with negative side waterproofing is its ability to withstand hydrostatic pressure. The pressure refers to the force water exerts in the soil against the basement walls. While exterior waterproofing systems address this pressure proactively, negative side waterproofing faces the daunting task of dealing with the pressure that has already breached the walls.

Corrosive Soil Materials and Their Consequences

Negative side waterproofing is particularly susceptible to the corrosive nature of soil materials. The minerals and salts in soil can compromise the effectiveness of waterproofing materials over time. This corrosion can lead to the degradation of the waterproofing treatment, rendering it less effective and requiring periodic maintenance or reapplication.

The Complexity of Application: Negative Side Waterproofing System

Applying negative side waterproofing involves meticulous techniques to ensure optimal effectiveness. Most commonly, a waterproofing coating is brushed, sprayed, or rolled onto the interior surface of basement walls. However, achieving uniform coverage and addressing potential weak points, such as cracks or joints, demands careful attention to detail.

Interior Humidity Limitations

One significant limitation of negative side waterproofing is its inability to address interior humidity effectively. While it can prevent liquid or vapor water from entering the occupied space, it does not actively manage or reduce indoor humidity levels. This distinction is crucial, as high humidity can contribute to mold growth and impact the overall comfort and health of the occupied space.

Positive Side Waterproofing vs. Negative Side Waterproofing

Traditional or positive side waterproofing involves applying a waterproofing material to the exterior of basement walls, acting as a proactive barrier against water intrusion. In contrast, negative side waterproofing addresses the issue from within. The choice between the two methods depends on various factors, including the severity of the water issue, the feasibility of exterior access, and the nature of the soil surrounding the foundation.

Positive side waterproofing is generally considered more effective in preventing water intrusion, as it addresses the source of the problem before it reaches the interior. While a viable option in certain situations, negative side waterproofing is often viewed as a reactive measure, dealing with water that has already penetrated the basement walls.

Assessing Structural Integrity

A thorough assessment of the structural integrity of the basement walls is essential. Look for any existing cracks, gaps, or weaknesses to ensure the waterproofing treatment’s effectiveness. Addressing these issues before negative side waterproofing is a critical preliminary step.

Consulting a Professional

Given the complexity of negative side waterproofing and its limitations, consulting a professional waterproofing contractor is advisable. Professionals can comprehensively evaluate your basement, recommend suitable negative side waterproofing materials and techniques, and ensure proper application. Their expertise can distinguish between a temporary fix and a long-term solution.


In the intricate world of basement waterproofing, negative side waterproofing presents a unique set of challenges and considerations. While it addresses water intrusion from within, its limitations in dealing with hydrostatic pressure, corrosive soil materials, and interior humidity necessitate carefully evaluating its suitability for specific scenarios.

Understanding the complexities of negative side waterproofing empowers homeowners to make informed decisions. Whether opting for traditional methods or exploring the possibilities of negative side waterproofing, the key lies in a thorough assessment, strategic application, and, when in doubt, seeking the expertise of professional waterproofing contractors.

Balancing the intricacies of waterproofing materials, the demands of the soil, and the structural integrity of the basement walls ensures a comprehensive approach to safeguarding your living space against water damage.