Parking Structure Waterproofing Systems: Sealers, Sealants, Expansion Joints & Deck Coatings

Every parking structure should have a waterproofing system in place. But your structure’s needs will vary depending on how it was originally constructed and how it’s been maintained over the years. There are four main types of waterproofing systems for parking garages: sealants, sealers, expansion joints and traffic coatings. Let’s take a look at the qualities of each, including application and performance.

Why is parking structure waterproofing important?

While most garages have an overall service life of approximately 75 years when properly maintained, a totally neglected garage may only last one-third of its intended service life. Waterproofing systems play a crucial role in maximizing your garage’s overall service life and should be replaced approximately every 7-15 years, depending on the type of system, to maintain optimum performance. If not managed well, water can cause major deterioration, and this deterioration may lead to costly structural repairs.

Waterproofing systems protect your parking garage by:

• Preventing corrosion of its internal steel framework
• Maintaining joint integrity between floors, walls and fixtures
• Eliminating leaks between different areas of the structure

Another benefit of waterproofing systems is that they help you provide a better visitor experience. For example, leaks from one floor to another may cause mineral-rich water to drip onto occupants’ cars. This water can damage the paint and finishes on these vehicles, leading to very unhappy customers. Additionally, a good waterproofing and drainage system allows for maximum utilization because you don’t have to close off areas of your garage due to ponding in certain parking spaces after a heavy rain.

Different types of parking garage waterproofing systems

Every waterproofing system is designed to prevent water from getting into vulnerable areas of your garage, though some are better than others. Sealers, sealants and traffic coatings — sometimes collectively referred to as parking deck coatings — should be carefully considered to ensure the best fit for your garage.

Waterproofing system options can also be impacted by your garage’s construction. For example, precast structures, which are engineered in a manufacturing facility and assembled at the building site, require special attention to waterproofing at the joints. Cast-in-place parking garages have internal steel reinforcement that is vulnerable to rust and corrosion, making it critical to replace sealants and coatings when they’ve reached the end of their service life.

Parking garage sealers

Sealers are a penetrating waterproofing solution that soaks into the concrete. Because many sealers exist deeper than surface level, they aren’t easily damaged by winter maintenance or extreme swings in temperature. They have a service life of approximately 10 years.

Sealers often cover large areas of your parking structure, sealing the concrete to reduce the risk of deterioration to the concrete itself and to its internal reinforcement. The biggest benefit of this waterproofing system is it offers maximum protection while still allowing a clear view of the structure’s concrete during inspections and assessments — unlike surface-level traffic coatings. That means deterioration can be caught and addressed early on, rather than staying hidden and worsening over time.

Parking garage sealant and expansion joints

Sealants are applied to joints to prevent water from leaking into other parts of the structure. Joint sealant is often made of polyurethane or another elastic material, and it needs to be replaced periodically as the material becomes brittle and begins to crack with age. Within a parking structure, the service life of joint sealants can be as much as 10-15 years, but the service life drops to 7-10 years if the joint has been exposed to UV light or extreme temperature fluctuations — as it would be on a roof, for example.

Additionally, expansion joints are specialized joints that allow your structure to expand and contract as temperatures change. This garage waterproofing feature, which includes compression seals, can protect your structure in areas where physical movement might damage typical joint sealants.

Expansion joints are the most vulnerable part of a precast parking garage, and even cast-in-place structures have joints between walls and floors that are susceptible to water penetration. Thus, the application of joint sealants and the maintenance of expansion joints are critical to keeping your garage in good shape.

Parking garage floor coating

Sometimes called a traffic or deck coating, this type of waterproofing system sits on the surface of your structure, as opposed to penetrating the concrete like sealers. Topical traffic coatings, such as paint systems, create a barrier between your structure’s concrete floor and the elements but are not intended for surfaces that support traffic. But despite these often being the cheapest, quickest way to combat persistent leaks, traffic coatings aren’t an effective long-term solution. Parking garage floor coatings are highly susceptible to wear and tear from winter maintenance. When snowplows travel over a traffic coating, they’re abrading and scraping the concrete surface to remove ice and snow. Unfortunately, that means they’re also damaging the traffic coating. This damage allows water to seep beneath the coating, and now the system put in place to protect the floor is actually trapping water and causing additional deterioration. And because traffic coatings obscure the view of the concrete beneath, it’s hard for experts to catch this deterioration during routine inspections.

Waterproofing failures and service life considerations

Parking structure waterproofing failures happen when these systems wear, crack, chip or become brittle due to improper installation, damage or age. Although the service life of a waterproofing system is less than that of a parking garage, proper maintenance can help you get the most out of the system you choose. That said, there are several conditions that affect waterproofing system service life, including:

• Snow Removal: Particularly with topical coatings, snowplows can damage or chip away at the system as they clear the deck.
• De-icing Chemicals: If not used properly, chloride-based de-icers can be destructive and even reduce the life of your waterproofing system.
• UV Light: Waterproofing systems on the roof of your structure that are constantly exposed to the sun will need to be replaced more often.
• Poor Drainage: Anywhere water is allowed to lay for a prolonged period may be more susceptible to waterproofing system failure.
• Extreme Temperatures: Constant freeze/thaw cycles or exposure to extreme heat can impact waterproofing, especially joint sealants.
• Dynamic Loads: Most parking structures are in constant flux as vehicles move around within them, and this movement can stress your system.

No matter what waterproofing system you need, routine inspections are necessary to ensure your parking structure is in good condition. Water is one of the most detrimental elements when it comes to maintaining your parking garage, so by putting a waterproofing system in place early, you can prevent any issues and avoid costly structural repairs.