Waterproofing

Waterproofing is the process of treating an otherwise porous surface to prevent the migration of water (or other liquids) through the substrate directly or through seams. This process is best accomplished on the positive side of the substrate: the side receiving the initial exposure. This discussion will focus on waterproofing of flooring applications such as parking decks, mechanical equipment rooms, balconies and pedestrian decks.

It is important to apply waterproofing systems to prevent the corrosion and deterioration of concrete in conditions exposed to continuous weather conditions. Indoor applications utilize waterproofing whenever there is a chance that water will have the opportunity to migrate to a lower floor. These cases may include pool areas, showers, mechanical equipment rooms and utility rooms.

Although concrete is the most widely utilized construction substrate, it does have limitations with respect to heavy wear conditions and its inherent porosity. In addition, concrete shrinks during its curing process and will expand and contract through seasonal temperature changes. For this reason, joints are constructed in the concrete to address initial shrinkage as well as continuous movement. Cracks in concrete are unplanned “natural” joints. When an area requires waterproofing it is these details which require a membrane waterproofing technique rather than a simple damp proofing penetrating treatment.

Membrane waterproofing systems are designed to provide a flexible watertight coating bonded directly to the substrate (frequently with the use of a primer). In order to protect this membrane as well as provide a slip resistant wear surface, one or more applications covers the membrane providing texture, durability, chemical and/or UV resistance. The chemistry of these membranes has evolved rapidly over the course of the last forty years. Initial seamless technology utilized latex chemistry which is flexible and non permeable.

The development of polyurethane elastomers improved upon the performance of waterproofing membranes and became the most widely utilized material for most exterior applications. Polyurethane elastomers can be constructed to be lights stable (Aliphatic versus Aromatic) and can vary in solvent content. Polyurethane elastomers have excellent elongation but bond strength to concrete is lower than internal tensile strength which permits a system to disbond from the substrate. Although this situation is advantageous over a moving crack, it becomes a problem in traffic situations if the membrane is compromised resulting in an undercutting of the system which is difficult to stop and repair. This relatively low adhesive strength of polyurethane systems requires the wear course layers to be constructed to accommodate the inability of the system to hold aggregate throughout its service life in high traffic areas.

Flexible epoxies were developed to address the limitations of polyurethanes. EPO-FLEX was the first of these products to be commercialized in the United States. It is 100% solids (no solvents), has low odor, and bonds tenaciously to the substrate and to the aggregate when used in a wear course. Although flexibilized epoxy materials are inherently more expensive than polyurethane elastomers. These systems are competitive because they require less material as sacrificial wear coats in heavy traffic areas. These systems have also been designed using stress relieving epoxy wear surfaces in situations not expected to experience a great deal of movement. Both epoxy and polyurethane systems are limited by the environmental conditions during installation. The temperatures must be greater than 50 F and humidity and dew point can affect both cure and adhesion.

The newest chemistry available for waterproofing is Polyurea. This technology was originally developed for injection molding due to its cure speed but modification has allowed its use as a spray applied membrane system. It has excellent flexibility, good adhesion when used with a primer, excellent abrasion resistance and most importantly cures in minutes at temperatures as low as -30 F. Cold temperature application may be most advantageous if the system requires off-season cold temperature repairs or additions. True Polyurea products, such as General Polymers’ EnviroLastic, unlike polyurethane or hybrids, are not adversely affected by moisture during application. By varying the material and the spray technique an aggressive surface can be applied over a parking deck Polyurea membrane which provides long term wear, slip resistant texture and a surface that can be easily cleaned.

Parking decks

Regardless of the system or chemistry selected for parking deck service, there are some common characteristics which must be addressed. These include:

  • Exposure to heavy vehicular traffic
  • A non-slip texture is required
  • Membrane must address constant movement and vibration
  • Joints and cracks must be detailed to accommodate movement
  • System must resist road and automobile chemicals
  • System must be Cleanable
  • Top Decks must be UV resistant
Systems Supplied by General Polymers Mechanical Equipment Rooms

As with parking decks, these systems must provide waterproofing but they do not experience the degree to abrasion and traffic conditions. In some cases these systems will utilize a simple smooth topcoat or a decorative finish. Movement in MER’s is substantially less than Parking structures but water exposure must be contained or pitched to a drain requiring cove base and drain details. Because MER’s are indoors, it becomes more important to utilize a low odor system. In some cases, it will be necessary to use 100% solids, no volatile organic solvents system to prevent fire hazards from water heaters or furnaces.

Systems Supplied by General Polymers

Pedestrian Walkways, Balconies and Decks

In these pedestrian deck applications, there are commonalities between MER traffic conditions and exterior weather conditions as experienced in parking decks. Pedestrian deck applications must withstand structural movement due to seasonal changes, handle light foot traffic, have an aesthetically pleasing appearance, be easy to clean and resist degradation by sunlight exposure.

Systems Supplied by General Polymers

When specifying a waterproofing system, consult with General Polymers to determine which system can best serve your application. In addition, we can offer you suggestions in addressing the transition, termination and joint details which are critical for the success of the waterproofing system.