Look Before You Buy

March, 2008

Assess a Parking Structure’s Condition

Decisions regarding the purchase of commercial property are typically based, in part, on the findings from a pre-purchase condition assessment of the property. The assessment is undertaken by a multi-discipline team of building professionals who have the knowledge and experience to quickly identify the condition of the property and develop meaningful predictions of the scope and cost of future repair, replacement and maintenance.
Parking structures, especially those in cold climates, are exposed to more severe conditions than most other buildings. Parking structures are more similar to bridges than to buildings. Vehicles bring in rainwater, snow and de-icing salts in cold climates. Roof-level and perimeter areas of open parking structures are exposed to windblown precipitation. Open, unheated parking structures must endure large daily and seasonal temperature variations. These harsh conditions can cause leakage and deterioration of structural components and require significant ongoing maintenance and several major concrete repair and protection cycles during the life of the structure, particularly for structures built before the advent of present-day durability measures.
Pre-purchase assessment of such structures requires not only expertise in structural engineering, but also knowledge and experience with the durability of parking structures and the often-subtle indicators of deficiencies, deterioration and distress that will require significant maintenance and repair. These skills are often beyond the experience-base of the engineers and technicians that commonly provide typical building inspections. And the commonly used inspection checklists and report formats fail to highlight the crucial issues.
The scope, time and cost of condition surveys and the testing necessary to identify the condition of a parking structure and to predict its maintenance and repair needs are usually more than a potential purchaser is used to spending on a more common building. However, the cost to repair and maintain a parking structure can be significant depending on its structural type, age and exposure conditions. Consequently, a typical pre-purchase survey should be conducted in two phases.
The first phase – initial assessment – typically involves the following tasks:
• Briefly review the structural drawings, architectural drawings and specifications representing the parking structure design. The purpose of this review is to become familiar with the structural and durability features of the parking structure.
• Contact local building officials to check for outstanding code violations.
• Interview appropriate members of the garage’s management staff to discuss the history of performance, maintenance and repair of the structure.
• Make a walk-through inspection of the structure. Although the inspection tasks may vary depending on the type of structure, the following tasks apply to most parking structures.
• Inspect representative as-built structural components for general conformance with the design drawings.
• Inspect the topside and underside of the parking decks, the columns and the walls to identify readily visible distress, deterioration, deflection, movement and leakage. It is particularly important to evaluate cracking and cracking patterns.
• Inspect expansion and sealant joints for readily visible failures.
• Inspect the condition of any waterproofing.
• Evaluate drainage systems.
• Randomly sound selected areas of the topside of the parking decks to identify the approximate extent of delaminated concrete.
• Inspect stair structures for deterioration and leakage.
• Inspect miscellaneous components for readily visible deficiencies, deterioration and distress. Such components include barrier walls, railings, light pole anchorages, curbs, lintels, masonry walls, drains and drain piping, lighting, fire detection and protection systems, doors, windows, and gates.
• Prepare a letter report of findings and recommendations, including the scope and cost of recommended short-term and long-term repair and protection work; identification of areas of concern, if any, regarding structural performance and/or durability; and recommendations for further investigative work, if any.
Cost estimates should be based on the scope for observed damages. If a full survey is not performed, the basis of repair quantities should be extrapolated based on areas that are observable. Engineering judgment is necessary when extrapolating, and the parameters and limitations of that judgment should be identified in the report.
The second phase – further investigation – might be necessary if the initial assessment reveals conditions of concern that require additional field work, testing and structural review to address suspected deficiencies. Additional investigative work, if any, will depend on the type of structural system and the types and extent of the conditions of concern.
Additional investigative work might include, but is not necessarily limited to, one or more of the following tasks:
• Comprehensive survey and documentation of conditions to better estimate quantities for remedial work.
• Field verification of the as-built location of reinforcement using reinforcement-locating equipment and ground-penetrating radar (GPR).
• Exploratory openings to examine the condition of reinforcing bars, post-tensioned tendons, pre-stressing strands and other embedded structural elements.
• Extraction and testing of concrete core samples to determine the general quality and durability features of the concrete.
• Field testing for corrosion activity.
• Field testing of the general condition of the concrete using ultrasonic pulse velocity (UPV) equipment.
• Field testing of structural response using impulse response (IR) and/or impact echo (IE) equipment.
• Calculations to review of the adequacy of suspect structural components.
• Exploratory openings to examine the condition of sealants and expansion joints.
• Extraction and visual examination of waterproofing, bond testing of waterproofing.
• Water testing to identify failed sealant joints and expansion joints.
A new owner of a parking structure can be faced with large, unexpected repair and maintenance costs if the pre-purchase effort is inadequate. Conditions that can lead to high unexpected costs include, but are not necessarily limited to, the following:
• Extent of delaminated concrete over corroded reinforcement.
• Distress and deflection resulting from construction and/or design deficiencies.
• Post-tensioned tendon deterioration, particularly of older systems not having present-day corrosion-protection and other durability features.
• Inadequate previous repair and strengthening efforts.
• Inadequate or nonexistent lateral-load resisting systems.
• Inadequate or nonexistent vehicle barriers.
• Need for and ability of exposed decks adjacent to buildings to accommodate fire trucks.
It is important to properly manage the potential purchaser’s expectations by carefully explaining the costs and benefits of various levels of evaluation effort, and by identifying any limitations in prognostications regarding the scope and cost of future repair, replacement and maintenance. The two-phased approach described herein provides a method to first quickly and efficiently gather information helpful in making initial purchase decisions and in deciding the needs for and benefits of additional evaluation.

Michael L. Brainerd is a Senior Principal and Greggrey G. Cohen a Senior Project Manager with Simpson Gumpertz & Heger. Their e-mail addresses are mlbrainerd@sgh.com and ggcohen@sgh.com.