Mechanisms that Drive Deterioration
Understanding the mechanisms that drive the rate of deterioration in parking structures is valuable to facility managers and engineers.
Progressive deterioration is something that will happen over time on any parking structure. Below we talk about the four situations that influence the rate of which a parking structure could deteriorate.
- Limitations of service life
- Construction & design related issues
- Inadequate or improper maintenance
- Isolated events
Limitations of Service Life
Even though today’s parking structures are designed to last 75 years or more, many components of a structure have a shorter service life. They will need to be replaced or substantially rehabilitated multiple times during the life span of the structure.
Service life is typically a function of materials, quality of construction, and the effects of exposure. Each component of a parking structure: sealants, sealers, expansion joints, coatings, cast-in-place concrete topping, drainage systems, line striping, etc., has unique material and construction properties. Each component is affected differently by exposure to the elements. Exposure is often a function of placement location and geography.
Examples:
- In the northeast, urethane sealants have a useful life of 7 to 15 or more years, depending on exposure to winter maintenance and ultraviolet light.
- Roof-level materials have a shorter life than materials used on lower levels.
- Drainage systems typically last 15 years or more.
- A properly maintained expansion joint system will last 10 or more years.
Collectively, these values are averages that should apply under normal conditions assuming proper and periodic maintenance.
An understanding of these averages and the factors that affect life expectancy is important. With this, facility managers and engineers can anticipate, preplan, and budget for major replacements and institute practices that maximize service life. The various components of a garage will require periodic replacement to maintain the functional integrity of the structure. The overall service life of the structure is dependent on maintaining this integrity.
Construction and Design-Related Issues
In a perfect world, quality materials, sound construction and design practices, as well as an experienced workforce make the general service life averages work. However, inconsistencies in the construction and design process, caused by a lack of experience, poor material choices and/or workmanship, and unrealistic demands of project leaders related to cost, and schedule can create conditions that often jeopardize the future durability of various components of construction. In parking garages these conditions frequently accelerate deterioration, increase the development of hazardous conditions, and create unplanned and expensive functional disruptions. Early evidence of these conditions serves as a forewarning to the experienced eye.
Examples of early evidence of poor design and/or construction:
- Ponding conditions or areas of poor drainage, caused by poor placement of drains, can create hazardous conditions in the winter and can accelerate the deteriorating effects of water absorption.
- Scaling or map-cracked surfaces may indicate improper placement of concrete, which can lead to an accelerated breakdown of concrete cover over critical reinforcing.
- Random cracking, which can be caused by improper tooling of joints and other causes, can create vulnerable conditions, particularly at roof-level exposure. Conduits, pipes, or penetrations through waterproofing materials can lead to persistent water penetration.
- Shallow concrete cover can be a significant issue if field quality control is lacking. Building codes dictate concrete cover to provide protection for the embedded reinforced steel.
The ability to recognize common gaps, deficiencies, and errors in the construction and design process at an early stage are important skills for facility managers and engineers. Being able to predict the future can fuel an early, focused, corrective response. The impact on controlling costs, minimizing disruptions and eliminating risk can be significant.
Inadequate or Improper Maintenance
Few things survive very long without maintenance. Assets like garages, as robust and durable as they seem, are dependent on sound maintenance practices to achieve a reasonable functional life. The current typical design life of a garage is 75 years or more. In the absence of periodic maintenance that life can easily be cut by 50% or more.
Proper maintenance, particularly of the most vulnerable components of a garage structure, is critical to maximizing service life, mitigating cost, and reducing hazards and risk.
Maintenance needs to include:
- A periodic inspection process to identify conditions at an early stage.
- Routine repairs to small, developing areas to slow down the rate of deterioration.
- A planned restoration process.
- Facility training for those that work in and around the garage.
- On exposed garages in cold environments, like the northeast, this training needs to include winter maintenance. The lack of proper and periodic maintenance is a significant cause for premature failure in parking garages.
Larger repairs and restoration, established through recommendations from the inspection process, should be planned for appropriate weather and scheduled to minimize impact on usage. These larger repairs should be addressed early enough to minimize avoidable damage.
A good maintenance practice, like comprehensive condition assessments of the structure by trained professionals at least every five years, is a wise investment. These should be supported by annual inspections where the trained professionals identify new developing conditions and validate previous assumptions.
Facility staff should also be trained to perform monthly visual inspections to guide housekeeping and small maintenance needs and to provide important feedback to the trained professionals engaged in overseeing the health of the garage. Periodic training of facility and vendor staff should occur to ensure an understanding of garage construction and the deterioration process and to instruct maintenance personnel how to properly perform their duties related to daily maintenance, power washing, and winter maintenance, with the least harmful impact to the garage.
Lastly, parking structures, exposed to cold weather or coastal environments where winter maintenance and salt air accelerate the deterioration cycle should be power washed at least once annually. Small developing conditions, identified during the annual inspection process, should be evaluated for root cause and, depending on the nature of the condition, repaired at an early stage.
Isolated Events
The last mechanism of deterioration relates to one-time events that cause major deterioration or damage. These are less common but important to note.
A few examples of these types of events include:
- Vehicle fires:
Concrete, although very durable, can suffer damage from high heat conditions. Fire in garages can cause damage to sealants, lighting, and electrical components. To determine the extent of this damage diagnostic testing is required. - Overloading conditions, like those caused by oversized vehicles or snowload:
Overloading occurs when large vehicles are permitted access to supported levels of a garage. Frequently this occurs in conditions of roof-level access without height restriction bars. Winter maintenance events sometimes cause overloading conditions. This can be due to vehicle weights, which can become excessive when loaded with snow, or stockpiling snow more than a few feet. In each of these cases, the load-carrying capacity of the structural elements can be exceeded - Earthquakes or flooding conditions:
Earthquakes and flooding conditions can create localized damage to structural elements due to violent shaking or impact from floating debris. Each of these events requires a different response usually involving an inspection and then appropriate follow-up action. In most cases, an engineer should be guiding this process.
Each of these mechanisms of deterioration is controllable with an educated, proactive team approach. A trained facility team supported by knowledgeable garage professionals can exercise great control over service life and predictability of repair and maintenance costs.
Start the conversation with a parking structure expert today on how to improve possible signs of deterioration.
Franc Genoese
Sr. Director of Technical Services