Spring Cleaning for Your Parking Garage – It’s Not Just about “No Mess No Stress”

Most people don’t give much thought to a parking garage. They glance around to familiarize themselves with the floor layout, note their parking level and space number, and then move on to their destination. Few stop to notice recently repaired concrete, shiny new bollards, and fresh paint striping. Even fewer realize the complex process behind maintaining a garage’s structural integrity and appearance.

Concrete is naturally porous, allowing substances on its surface to be absorbed over time. Vehicles entering the garage bring in water, chlorides, and other contaminants that saturate and migrate through the concrete slabs, eventually coming into contact with embedded reinforced steel. When the reinforcing steel is exposed to water and air, corrosion begins to develop on the embedded steel elements. As the corrosion progresses, the steel exfoliates and creates expansive forces, which leads to cracks, delamination, and spalling. These defects further expose the reinforcing steel to air, moisture, and chlorides, which accelerates the deterioration.

After completing an extensive maintenance process, it is understandable that the garage owner would want to mark the task as complete and consider it a job well done — at least until the next evaluation. However, just as regular maintenance is crucial for the garage itself, maintaining the traffic coating is equally important to minimize the need for repairs in the future. Not only does it enhance the garage’s appearance by creating a uniform surface, traffic coatings also provide a protective layer over completed repairs. It serves as a barrier against chemicals brought in by vehicles, such as chlorides, while also minimizing moisture infiltration and reducing general wear and tear on the surface. This additional investment helps extend the lifespan of the repairs and maintain the overall integrity of the garage.

Traffic coatings safeguard new concrete repairs but what protects the coatings themselves? The effectiveness of traffic coating relies on its integrity. If the membrane becomes punctured or torn, water and chlorides can penetrate through and into the porous concrete, leading to delamination and spalling, as discussed earlier. Tears in the membrane can occur due to a variety of factors.

One situation that can damage the traffic coating occurs when vehicles enter and exit the garage, bringing in debris like rocks and twigs from the outside. As vehicles drive over this debris, it can create microtears in the traffic coating, allowing chlorides and water to reach the underlying concrete and penetrate the surface.

Another common issue arises during the snow removal and de-icing process. Garages often use snowplows to clear large amounts of snow, and it’s crucial that rubber-tipped snowplows are used to avoid scraping the coating with the steel blades, which can cause rips and tears. Additionally, sand and de-icing salts are typically applied to create traction and melt ice. As the ice melts, sand remains in the garage, and much like the debris mentioned in the first scenario, it can be driven into the traffic coating by vehicles, creating microtears. Excessive de-icing salts are often used to prevent slipping hazards, but these salts contain harsh chemicals that, through the microtears, can penetrate the traffic coating and create a corrosive environment, breaking down the coating material over time.

Installing the appropriate traffic coating system helps prevent water and chlorides from penetrating the concrete, significantly slowing the deterioration of the wearing surface and extending the lifespan of the structure.

Before traffic coating can be installed, all identified concrete deficiencies must be repaired, and the surface must be properly prepared according to the manufacturer’s specifications. Once the area is cleaned and prepped, the coating is applied in multiple layers, with each layer requiring adequate curing time before the next can be added. During this process, the coated area must remain closed, which can impact the garage’s total capacity and revenue, depending on its size and location. Only after the full system is installed and fully cured can the area be reopened for public use.

While routine maintenance is always required, a simple yet effective maintenance task to reduce microtears and traffic coating damage is performing a spring and fall washdown of the garage. This involves power washing the traffic coating in the spring to remove de-icing salts, sand, oils, grease, and debris left behind by vehicles over the winter months. An additional power wash at the end of summer helps clear away dirt, oil, grease, and debris accumulated during the warmer months.

Even without a traffic coating, a spring and fall washdown is highly beneficial for the garage, serving as an important form of preventive maintenance by removing contaminants from the top of the porous concrete surfaces. By taking these proactive steps, the lifespan of the traffic coating, concrete surfaces, and the underlying garage structure can be extended.  

Kathryn M. Crouchley, E.I.T.
Gale Associates, Inc.

Kathryn M. Crouchley, E.I.T. is a Senior Staff Designer in Gale Associates, Inc.'s Structural Engineering Group.  She develops structural engineering solutions for the design of new facilities and rehabilitation of existing buildings.  Ms. Crouchley performs condition assessments and prepares contract documents for parking structure repair projects, performs structural calculations, conducts building enclosure evaluations, and engineering for exterior building enclosure rehabilitation projects including forensics, design, coordination, preparation of specifications and construction phase services.