By: Anthony Ngadimin
July 28th, 2021
Parking garages in cold climates can be subject to extensive corrosion of steel members, steel reinforcement and accelerated deterioration of the concrete or asphalt surfaces. Vehicles track in significant amounts of de-icing salts from the streets; open garages may apply countless applications of de-icing salts during the winter months to maintain serviceable conditions. These salts can penetrate deep into the pores of unprotected concrete surfaces and are detrimental to the embedded steel reinforcement. Over time, the embedded steel reinforcement will corrode and result in displacement of the concrete which causes cracks, spalls and the potential for costly repairs.
There are coating systems for parking garage surfaces that are intended to protect the concrete from water intrusion and particularly serve as protection from deicing salts. Not all coating systems are suited for the same application. There are sealers, vehicular traffic coating systems, and heavy-duty versions for heavy trucks, as well as turn lanes and ramps.
Clear Penetrating Sealers
Penetrating sealers are liquid-applied and include a group of compounds known as silanes, siloxanes, and silicates. These compounds penetrate deep into the pores of the concrete and prevent water molecules from allowing vapor permeability. This is particularly important where vapor drive is present (i.e. slab on-grade or on the soffit of an elevated deck).
Penetrating sealers are relatively inexpensive and can be quickly applied. These sealers are a good option if the parking garage is in an overall good state of repair and is not exposed to deicing salts. It is important to note that these sealers typically require maintenance every 5 years or less.
Methacrylate and Epoxy Sealers
Methacrylates and epoxy sealers may be used to restore concrete parking garage decks that have already sustained some extent of wear and tear, damage or distress. Methacrylates and epoxy sealers protect the concrete and prevent chloride intrusion.
Before the application of these system types, the existing concrete surface of the parking garage requires the removal of all oils, bond breakers and loose material, in order to prepare for the coating systems. Grinding, shot blasting are often necessary steps to ensure the concrete surface profile (CSP) meets the minimum requirements of the manufacturers’ system application. A well-prepared surface will help ensure a good bond between the new system and the concrete surface.
Elastomeric Traffic Bearing Membranes
If the parking garage is in a state of advanced deterioration, the elastomeric traffic-bearing coating systems may be considered for extending the lifespan of the concrete surface. Unlike clear penetrating sealers, methacrylates, and epoxies, elastomeric coating systems are often applied in multiple applications, which typically includes a base coat, a wearing layer, and a topcoat. These systems are typically warrantable for a 5 year period, but can last much longer depending on the rate of wear and tear. Some manufacturers allow for a 5-year recoat within the 5 years, for another 5 year warranty extension.
Considerations for Choosing the Right System
There are other factors to consider, such as UV exposure, snow removal, and budget limits, which varies depending on the requirements of the parking decks. When planning a restoration effort, it is important to plan for annual maintenance and a cyclical capital improvement project to continually protect the parking decks for the expected lifespan of the structures.
There are many elements on a parking deck that are often not considered in the coating system application until a survey is performed. The drains and plumbing lines are often in a state of deterioration when there are significant deposits of deicing salts. It is almost for certain, that the drains must be replaced during a comprehensive coating system application. Expansion joints in parking decks and wall systems are also typical components for full restoration efforts. In the event that the parking spaces do not meet the code requirements or ADA handicap requirements, then there is a possibility that an updated striping plan may be required after a new system is applied. When evaluating the extent of repairs, there are different tests that can be performed to check the alkalinity of the concrete, integrity of the concrete deck, and PSI of the concrete. Additionally, where there are cracks, spalls, and delaminated concrete, the repairs can be a very significant percentage of the budget.
As part of a parking deck or garage survey, the recommendations should be suited to address the conditions of the concrete. The improper selection of products not only leads to unnecessary costs but may also result in further damage to the structure.
The first step to a successful garage or parking deck restoration project is retaining an experienced Engineer or Architect to assess the structure and provide detailed recommendations for a comprehensive restoration plan. Based on the unique characteristics of the parking garage, the Consultant should work with Building Owner and Property Manager to develop a design that will resolve any active or potential water infiltration conditions; efforts to stop existing damage and repair deficiencies is almost certain to elongate the lifespan of the structure. During the design phase, detailed drawings and specifications will be prepared for bidding to garage and parking deck restoration contractors; a robust construction administration effort and oversight will help ensure that the construction is adequately providing quality control oversight in the multiple phases of a restoration effort. Please feel free to reach out to Sullivan Engineering if you have any questions about successful parking garage restoration projects.