Parkade Restoration 101

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Posted: June 6, 2017

By: Norm Braddock, B.Sc., C.Tech

Parkades are an important aspect of many residential condominium buildings and can act as the foundation for these types of structures. Therefore, maintaining parkade areas is critical to ensure the safety and comfort of residents.

Underground Heated Parkades

Many condominiums have under­ground heated parkades with internal multi-level suspended concrete parking areas. Restoration of these parkades represents a major expenditure in the capital costs for condominiums. This is especially true for parkades, which have been neglected and not maintained for long periods of time.

During the winter months, in colder climates, deicing salt is used extensively on   roadways. The composition of salt includes chloride ions. Salt laden snow and ice are retained by cars, which enter into parkades. As soon as a vehicle enters into the parkade, the melting of the snow and ice begins. Initially, at the trench drain area, through the drive isles and finally at the parking stall areas where the greatest amount of melting occurs. Concrete is a porous material which all allows water to penetrate to the reinforcing steel within it. After the melting process has occurred, the chloride-contaminated water reaches the reinforcing steel. The chloride acts as a catalyst and an electrochemical reaction results in the development of corro­sion. The reinforcing steel expands as it corrodes and eventually “pops” or spalls the concrete. If left unattended for prolonged periods of time, extensive growth of corroded areas can occur resulting in the loss of service­ability of areas of the parkade. In some instances the complete closure of parkades has to occur. In such instances the reinforcing steel may have de­teriorated to the degree that the integrity of the structure is compromised. At this point, a tremendous amount of disruption to tenants occurs combined with high fees to repair the structure. Costs ranging from hundreds of thousands to over a mil­lion dollars are not uncommon in such in­stances. To avoid unexpected high restoration costs and major disruptions to tenants, it is recommended that parkade evaluations be conducted to determine the extent of con­crete delamination’s. Bi-annual evaluations are recommended after a major restoration of the parkade has been completed.

Parkade evaluations typically consist of an overall assessment of the parkade. A chain drag assess­ment is included where a chain is used to determine areas of delaminated or spalled concrete. The “popped” areas or top surface delaminated areas of concrete typi­cally make a hollow sound as the chain passes over them. Similarly, areas of sof­fit (ceiling) delamination’s are identified by hammer sounding suspect ar­eas. Top surface and soffit delamination’s are quantified and repaired during restorations.

Assessment of trench drains, leakage though walls and a condition review of the existing traffic deck coat­ing systems are also conducted during a parkade eval­uation. A common misconception is that once a parkade has been restored, and after having a traffic deck coat­ing system installed, that the parkade will not require repairs for several years. During a parkade restoration, areas of concrete, which have sounded with the ham­mer or chain, are repaired. However, areas where the corrosion process has not progressed to the point of sounding are not restored. These areas will continue to deteriorate and should be repaired at the point of sounding. Maintenance repairs of a parkade are recom­mended biannually after a major restoration has been undertaken. A parkade is a major investment and the upkeep of it is a reality and a necessity.

During parkade restorations, improvements or addi­tions to the parkade can be conducted in conjunction with the restoration. Examples of which are electrical or mechanical upgrades, re-painting of the parkade itself and/or the addition of drains to facilitate drainage.

Plaza Waterproofing

Most underground heated parkades are situated beneath the existing buildings. Typically, the confines of the parkade extend beyond the perimeter of the build­ing with landscaping or parking situated over the con­fines of the parkade below. These areas are referred to as the exterior plaza area. During the 1970’s two protective coatings used over these plaza areas were liquid rolled applied mate­rial and inter mopped asphalt felt. As time has pro­gressed, these materials were found to be deteriorated resulting in water ingress into the parkade. Success has been achieved using epoxy or ure­thane injections into the soffit (ceiling) of the plaza deck. Success has been dependent on the product used, by the skillset of the applicator and the severity of the water ingress.

There are instances where soffit injections cannot be conducted or may not be economically feasible due to the quantity required. In such circumstances, complete removal of the existing plaza landscaping and concrete topping are required. After concrete repairs are conducted to the plaza slab concrete, a new water­proofing membrane and new insulation are installed. The landscaping, new concrete topping or alternatives can then be installed. Success has been achieved with the use of multi-urethane injections. These injections are costly but have been proven to be effective in preventing wa­ter ingress into the parkade. Typically, multi-urethane injections are conducted in conjunction with plaza wa­terproofing replacements. Costs for the complete removal and replacement of the plaza waterproofing can run into the hundreds of thousands of dollars. A consultant can then direct the condo board or strata corporation  as to which method is best suited for the site.

Disruptions

Complete closure of a parkade during a restoration is sometimes required due to structural concerns. Also, there is a cost benefit and a timesaving’s factor for al­lowing complete access to the parkade by the contrac­tor. However, restoration   can also be  achieved by phasing  parkade repairs. During the restoration, sections of the parkade are closed while allowing tenants to have access to other areas while the work is in progress. After each area is repaired, another section is closed and the process re­peats itself until all delamination’s are repaired. The same process for the installation of the traffic decking system can be repeated. It is imperative to note that each parkade is unique and there are instances where total closure of the parkade is necessary for brief periods to complete concrete repairs or to install small sections of traffic deck coating. However, this complete closure may be for a few days in comparison to a total shut down for weeks or months.

Regardless of the concrete removal method used, dust and noise are a reality of restoration projects. Care can be taken to hoard these inconveniences in work areas, however, dust at­tributed to sandblasting will be present but to a lesser degree. Noise associated with hydro de­molition is standard during restora­tions. With residential complexes hours of noisy work are typically completed during typical business hours. On Saturdays, noisy periods of work can be conducted starting later in the morning until mid-afternoon. Typically it is recommended that no noisy work is completed on a Sunday.

Exterior Unheated Parkades

These structures experience similar concrete dete­rioration as those of heated parking garages. However, they do not experience the frequency of continual melt­ing as do underground heated parkades. Evaluations can only be conducted during the spring, summer and fall months when temperatures permit for proper chain dragging to occur. Below certain temperatures, the hollow sound of delaminated concrete fails to be heard. Typically, such assessments can be conducted from April to October, weather permitting. Delamination repairs are also typically conducted from April to October when temperatures are conducive to allow the new concrete to cure and for the proper in­stallation of the new traffic deck coating system.

Consultants & Contractors

The first step in beginning the restoration process is to retain a qualified consultant who can conduct the ini­tial evaluation. From the evaluation, budget and a project plan can be developed and provided to the respective board or strata as to how the restoration should proceed. A complete engineered specification with drawings is then competitively tendered to two or more reputable contractors. When the restoration is underway, the con­sultant conducts restoration site reviews and monitoring of the overall project. The vast majority of boards or strata corporations prefer the consultant to carry out the project from start to com­pletion. Structural engineering is part of  parkade restoration projects. Of course, the client is notified and kept abreast of the project at all times during the pro­cess. It is extremely important that a reputable contractor is chosen who has had a track record of proven and reputable experi­ence in parkade concrete restoration. Any prospective contractor should provide a list of previous restoration projects as well as references.

 

Suspended parking structures and exterior park­ing/plaza areas represent a major investment for any condominium complex. A concrete parking structure is prone to deterioration due to climatic changes  and the conditions associated with these changes. Neglect of maintenance will amount to  high costs for repairing the structure and potential disruptions for many stakeholders. Maintenance re­pairs and evaluations are a necessity to prolong the serviceability of the structure. Good guidance from a consultant and skilled workmanship from a contractor can protect these investments.



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