By Ben Smith, B.E.Env

Multi-story parking lots are unique buildings, one in which all elements of the structure are normally exposed to the public. These structures face unique challenges as well as exposure to niche stresses as well as physical and chemical abuse.

Although often underestimated, the correct specification of waterproofing and surfacing materials is critical, within parking environments, to delivering a long-term, structurally protected and safe facility for parking operators and vehicle owners.

The most suitable deck coating material will largely depend on where within the multi-level or underground parking facility they are to be installed as well as the conditions to which the material will be subjected.

This can range from slip-resistance, durability and service life requirements through to temperature cycling, UV exposure and any problematic existing substrate conditions as well as any anticipated movement within the structure.

Parking has become a vital part of today’s mobile world with more vehicles on the road than ever before. As a result, the demand for parking is at an all-time high with vehicle owners searching for secure and safe environments to house their vehicles when they are without them.

The parking lot is often the first point of call for a visitor to any public, private or commercial venue. It is the “front door” of the building, while at the same time serving its primary functional role. There is no doubt that initial appearance, ease of use, signage, bright lighting and clear directional marking all help to make a parking development a more positive and safer environment.

As new build multi-story and underground parking structures are more frequently adorning the urban landscape so too are older structures being renovated to meet both modern design and safety requirements.

One critical design consideration is the deck coating material chosen to protect the reinforced concrete structure, in order to protect against the access of water as well as corrosive de-icing salts and other pollutants.

Although polyurethane based deck coating systems are most common, acrylic (MMA) systems are increasingly being specified. MMA deck coatings offer fast cure installation in order to keep disruption of operations to a minimum during renovation. In addition, the performance of these systems is significantly better when compared to polyurethane deck coatings, allowing to be re-coated when maintenance is required, keeping the integrity of the system.

Resin systems are installed at various thicknesses dependent on the specification, not only to protect the substrate but also to improve aesthetics and safety, ensuring a welcoming impression for visitors.

Parking lots, like no other structure, are subject to unique conditions, which demand deck coating systems proven
beyond doubt in the protection of buildings subject to multi-traffic movement.

Applied coatings, whether on the wall, deck or soffit, must perform to meet the most stringent of criteria if they are to succeed in their primary function of parking deck protection.

Failure to protect the concrete slab, will inevitably lead to long term maintenance plans, increased operations costs and in extreme cases, deck failure.

The nature of multi-story parking lots demands that they are constructed with large clear spans with a minimum number of supporting columns, in order to achieve the maximum number of parked vehicles. This type of construction, when subject to cyclical traffic flow, inevitably leads to the structure being susceptible to flexing and movement.

A high volume of vehicles crossing a parking structure over time can lead to dynamic loading, where vibrations impart through the decks into the structure, increasing the risk of movement across all construction, expansion and movement joints within the frame of the structure and decks themselves.

In order to counteract the risk of dynamic loading, flexible, crack-bridging polyurethane based deck coatings systems are often used to move alongside the structure, preventing any long-lasting damage to the surface or the building itself.

Often fully exposed to the environment, multi-story parking lots are subject to high temperatures, extreme sunlight, UV exposure, low temperatures, freeze/thaw cycles, high levels of rain and extreme temperature fluctuation.

All of these can impact negatively on the structure, imposing dynamic stresses, which will inevitably lead to the early cracking of the host concrete and potential structural failure.

Again, specialist resin-based decking coating systems act as a protective coating by accommodating thermal movement in order to prevent thermal cycling over a 24hour period or seasonal change from posing any lasting damage.

Significant traffic exposure causes mechanical wear and abrasion of the surface, which is naturally increased on parking ramps, pedestrian walkways and in turning circles. This is also true of exits and entrances from the parking lot into a commercial venue as well as at elevator waiting areas.

The deck waterproofing and wearing surface systems selected to protect decks must off suitable skid, slip and abrasion to ensure safety underfoot. Using positively textured aggregates, the anti-skid profile of the surface can be increased in areas of high stress.

Airborne water, de-icing salts and automotive fluids; anti-freeze, battery acid, AC fluid, diesel and gasoline as well as toxic gases from exhaust pipes are all examples of aggressive chemicals and pollutants to which the parking structure is exposed.

Highly resistant resin-based decking coating systems can be used to prevent the early onset of corrosion, providing a protective barrier between the contaminants and the host substrate.

Pigmented resin coating systems will transform a parking structure; protecting it over time while simultaneously brightening up the environment with the addition of color, improving lighting levels through its reflective properties and enhancing the overall ambience of the parking lot, making it a safer and brighter place for people to park.

Colored line marking products can also be installed in conjunction with resin based solutions to define both pedestrian and vehicle areas, ensuring the safety of both people and cars by regulating traffic flow and pedestrian movement.

Taking this into account, the blueprints of multi-story and underground parking facilities must consider the unique structural design associated with parking structures as well as a range of aggressively corrosive service conditions, at specification stage, in order to ensure the optimum service life free from major repair or early renovation.

Like any other building, each one of the areas that are part of a parking structure have their own needs and these can be addressed with customized deck coating systems, always keeping high performance standards.

About the author: Ben Smith is the National Manager (Canada) for Flowcrete Americas.

For more information on suitable deck coating systems for commercial parking venues please contact Flowcrete Americas, specialist manufacturers of polyurethane and MMA deck coating materials, www.flowcreteamericas.com or +1 800 218 1850