Navigating the Choices: A Comprehensive Guide to Waterproofing Options

Waterproofing is essential in construction, but since there are so many application types available, choosing the right method can become a complex decision. Factors, such as geographical location, hydrostatic pressure, and temperature limitations, play a significant role in determining the appropriate waterproofing system. In this guide, we dissect different methods to help you make a more informed decision.

FOUNDATIONAL DEFINITIONS IN CONSTRUCTION

In the vast world of construction, terminologies can often leave some of us puzzled. Two such terms are “above-grade” and “below-grade.” As the names suggest, “above-grade” refers to structures or portions of structures that are above the ground level, while “below-grade” pertains to those below the ground level. It’s vital to distinguish between these two because they demand different protective measures.

Waterproofing systems are primarily applied below-grade. This is because structures below the ground are more susceptible to hydrostatic pressure and moisture ingress, as they’re in direct contact with the soil and groundwater. Ensuring that these parts of the building are waterproofed is crucial to prevent potential damage and maintain the structural integrity of the building.

On the flip side, above-grade parts of buildings, which are exposed to air and external environmental factors, require air and moisture barriers. These barriers safeguard the structure from external moisture, temperature variations, and prevent the infiltration of unconditioned air into the building, and exfiltration of conditioned air from the building. Essentially, while below-grade protections focus on keeping water out, above-grade protections prioritize maintaining the desired indoor environment and ensuring the external facade’s longevity. That being said, there are a few situations where you might need to waterproof above-grade; it’s just not very common. Examples of this could be roofs or parking garages.

APPLICATION METHODOLOGIES

Initiating the waterproofing process involves evaluating the structure’s age and accessibility. For new constructions, accessibility is typically not a concern unless the structure is right up on the property line. Therefore, waterproofing can be planned and executed with ease, ensuring the method can be tailored to the specific type of application desired. However, for existing structures, the approach to waterproofing must be adapted based on the level of access available to the targeted areas requiring treatment.

1. Positive Side Waterproofing: The waterproofing membrane is applied to the exterior, or the ‘wet side’, of the concrete; which does require access to the outside face of the structure. Positive side waterproofing offers excellent defense against moisture and protects the entire internal structural components. All types of cementitious, sheet and fluid-applied waterproofing systems can be applied with the positive-side.
2. Negative Side Waterproofing: In this technique, the waterproofing membrane is applied to the interior, or ‘dry side’, of the concrete. This interior application method only defends the inner surfaces and is traditionally used for repairs or when positive side application is no longer feasible due to the exterior access being unavailable. Cementitious systems are normally best, since these products can withstand hydrostatic pressure and have breathability, which prevent water vapor and debonding from the substrate.
3. Blind Side Waterproofing: This method is particularly used in constrained environments, such as when a new construction is adjacent to an existing structure or property line, making traditional exterior waterproofing impossible. In blind side waterproofing systems, protective layers are applied before the concrete structure is poured. Typically, this involves the use of specialized materials, or lagging materials, that are affixed to the neighboring structure or soil retention system. When the concrete is poured, it adheres to this pre-installed membrane, creating a waterproof barrier that is “blind” or sandwiched between the new wall and the adjacent structure or element. This effectively mitigates moisture infiltration and is activated and sealed as it gets wet, ensuring a dry and protected interior.

KEY CONSIDERATIONS

Once your project’s accessibility is determined, you next need to consider various design aspects when determining the best waterproofing system.

• Site Conditions: The physical layout of a building site often determines the type of waterproofing required. For instance, in confined spaces where structures are close to property lines, blind side waterproofing becomes a necessity since accessing the exterior for positive side waterproofing becomes impossible.
• Hydrostatic Pressure: The site’s hydrostatic pressure is a key factor in choosing a waterproofing method. Systems like bentonite products and elastomeric sheets, which are chemically or heat welded, are often chosen for their ability to withstand high hydrostatic pressures compared to other systems.
• Temperature: The effectiveness of a waterproofing system can also be influenced by temperature. Some materials and installation techniques are affected by low temperatures, especially those involving solvents, adhesives, and sealants. It’s crucial to adhere to the manufacturer’s guidelines on temperature constraints to ensure the effectiveness of the waterproofing application.
• Drainage: Efficient drainage is essential for both vertical and horizontal waterproofing applications. Specific membranes, like hot rubberized asphalt, are suited for low or no slope surfaces but are unsuitable for lightweight concrete fill. The incorporation of efficient drainage systems atop the membrane is critical to manage water effectively.
• Insulation: In most instances, enhancing a building’s thermal performance necessitates the incorporation of insulation into the waterproofing system. Insulation materials should be chosen based on their ability to resist water absorption, especially for below-grade applications.
• Structural Integrity: The waterproofing system generally does not impact the structural integrity of a building. However, additional considerations, such as load-bearing capacity and adaptability to various weather conditions, are essential when dealing with green roofs and plaza decks.
• Building Codes: Compliance with building codes is mandatory, and these codes often dictate the minimum required waterproofing systems, especially in areas prone to hydrostatic pressures.
• Detailing: Attention to detail is paramount in the waterproofing process, especially at penetrations, joints, and transitions. In blind side systems, particular care is needed due to the complexity of installation and the potential for water intrusion at specific points.
• Penetrations, Cracks, & Joints: Most leaks occur at penetrations, cracks, and joints. Addressing these areas effectively is essential. Protecting the reinforcing steel in the concrete wall is also essential to prevent oxidation and further cracking.

WATERPROOFING MEMBRANES & ACCESSORIES

Waterproofing systems encompass a range of accessories, each playing a vital role in fortifying your structure against moisture intrusion. Here’s a glimpse into these essential components:

• Primers: Waterproofing system primers prepare the concrete surface, ensuring optimal adhesion for subsequent waterproofing layers. They are specialized coatings that enhance the adhesion and ensure a strong bond between the substrate and the waterproofing system.
• Drainage Sheets: Drainage boards, or sheets, are essential for efficient water management in both vertical and horizontal applications. These offer not only added protection but also facilitate the proper flow of water away from the structure, preventing potential damage.
• Protection Layers: Protection course, often composed of materials like protection board or protection fabric, safeguard your waterproofing system from mechanical damage, UV exposure, and other external factors, enhancing its longevity and performance.
• Membranes: Choose from a variety of membrane types, to tailor your waterproofing to specific conditions. These membranes act as the primary barrier against moisture infiltration. There are fluid-applied, sheet-applied, hot rubberized, cementitious, and so many other types of membranes, each with their own benefits for different project types.

WEIGHING ALL THE OPTIONS

Selecting an effective waterproofing system is a balance of various factors, including application type, site conditions, and material properties. Understanding these elements is crucial for a successful waterproofing endeavor that stands the test of time, weather, and environmental conditions. The right choice, complemented by proper design and field inspections, ensures the structural integrity and durability of your new or existing structure.

For comprehensive solutions and expert guidance on your next project, consult with a waterproofing professional who can recommend products for your project’s specific needs, ensuring optimal protection and longevity to your structure.

 

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