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    1. Industry News

    Forensic Engineering

    Feb. 3, 2005
    Extending the life-cycle of buildings
    With facilities managers increasingly focused on bottom-line results, the lessons learned from forensic engineering offer tools that can bring about significant building operating and maintenance cost savings. Forensic engineering is essentially a process of diagnosing facility problems and providing solutions, employing a “holistic” view that takes into account all the elements of a building. Perhaps more importantly, forensic engineering can be employed as part of a preventive strategy, helping to anticipate problems and implement corrective actions before failures occur.The lessons from forensic engineering, coupled with a reliability-centered maintenance process, enable a facility manager to adjust the scope and frequency of periodic maintenance and preventive maintenance based on the past performance of existing equipment.One of the most important lessons highlighted by forensic engineering investigation is the importance of periodic inspection programs that assess (in detail) the condition of a building’s assets (e.g. building systems and structures and all equipment for operating the building, including elevators). The process requires a trained forensics expert with intimate knowledge of the systems being analyzed. While a system-specific engineer can solve a particular problem, the forensics expert will also look at the broader picture to understand the environment in which the component must successfully operate.The trained and experienced forensic engineer will not have a bias toward an individual piece of equipment or component type. For example, indoor air quality problems in major buildings are usually investigated by an environmental consultant. Yet, they are commonly caused by factors related to the building structure and exterior envelope, as well as the building’s HVAC system. Sometimes the exterior envelope and HVAC operation interact in ways that create conditions conducive to the indoor air quality problem.Another example in the architectural and structural engineering area is leakage through waterproofing systems that produce structural damage, including cracking in reinforced concrete and reinforced masonry and corrosion of structural steel. In both cases, analysis must be done which overlaps several disciplines and takes a comprehensive look at the entire structure.Failure PatternsWhile no list has been compiled with regard to which building components fail most frequently and why, there are patterns that lead a trained eye to the root causes of problems.An investigation of mold on the exterior walls of a high-rise residential development was recently performed. Upon initial inspection, it looked as if the mold growth was a result of water passing through the exterior wall of the building. The true cause, however, turned out to be quite different: Inadequate make-up air to the apartment units created a pressure differential between the inside and the outside, drawing humid air through the wall to the drywall. The resulting condensation of moisture vapor encouraged the mold growth. The solution involved repairs to both the exterior wall system and the mechanical ventilation system.Even with the knowledge that there are patterns of failure by building type, there is no comprehensive checklist for building owners and/or facilities managers to enable them to prevent failures. However, for new buildings, commissioning efforts can help make sure the building, its components, and operation and maintenance practices are off to a good start. For existing buildings, property condition assessments, mechanical inspections, and operation and maintenance assessments that are performed by specialists in their respective fields can be used to identify problems before components and equipment fail.Detection DevicesForensic engineers have both non-destructive methods and invasive methods by which an investigation is conducted. The non-destructive methods include a detailed visual examination by an expert and use of electromagnetic detection equipment, infrared imaging, ground-penetrating radar, and X-ray imaging.Invasive methods of investigation require cutting into building materials to inspect concealed details in the construction. Tools such as borescopes, fluorescopes, and videoscopes can minimize the amount of material that must be removed for the inspection. Invasive testing methods may involve removing a sample of a pipe, wall, or material and submitting it to laboratory analysis. The benefit is that the analysis provides specific details as to what might be causing, for example, corrosion in a pipe. The bottom line is that materials testing is often required to determine the proper specifications for repair, especially when dealing with structural and architectural systems.These and other forensic engineering services can cost the building owner from a few thousand dollars to hundreds of thousands of dollars, depending on the size and complexity of the problem. However, there is a cost benefit. For example, at a project in Florida that called for the replacement of the building’s ventilation system, an assessment of the internal design specification and drawings for the replacement system identified concerns with the means and methods being used for the construction. The assessment team was concerned that the building’s environment would not be properly maintained during construction. The owner went ahead with the replacement construction, and sure enough, the construction led to extensive mold problems.Uncovering DeficienciesForensic engineering can often be employed to uncover construction, design, and/or maintenance deficiencies. The process frequently brings to light areas in which a building contractor did not follow design specifications. A common example is the installation of flashing in an exterior wall system, which requires clear design specifications and tight quality control during construction.In addition, forensic engineering often reveals design flaws. As the previous example of mold contamination shows, the deficient design of the mechanical ventilation system led to a significant problem for the building.Today, mold is one of the most common problems facing building owners. It is also very difficult to pinpoint the source of mold, a process that requires the type of multidisciplinary approach that is the hallmark of forensic engineering. The mold example cited earlier was solved through the work of an environmental expert, then a structural engineer, and finally a mechanical engineer who was able to determine that the problem resulted from a mechanical issue.Pipe corrosion is another common problem whose root cause is usually difficult to determine. The way mechanical equipment is operated and maintained affects the corrosion-rate experience, but it is not always possible to go back and assemble a history of operations and maintenance procedures that might be the cause of corrosion. Looking ahead, forensic engineering practices will recommend better maintenance and record-keeping procedures that can forestall such a situation.Enhancing DesignForensic engineering efforts can also benefit new buildings, providing recommendations for elements to incorporate into the design that will enhance life-cycle rates and result in lower maintenance costs. This might include use of conventionally reinforced structures instead of cast-in-place reinforced concrete that uses rebar or post-tensioned concrete. Both types will fail when the reinforcing is exposed to moisture, and post-tensioned structures are generally far more expensive to repair. However, the additional material cost of a conventionally reinforced structure, which uses more concrete and steel, is offset over the service life of the building.With roofing, forensic engineering has shown that the details of the penetrations are the critical elements that affect the life of the roof.Whether it’s with new construction or an analysis of existing building systems, forensic engineering is a means to evaluate system performance. The process results in enhancements that not only solve immediate problems, but will bring about cost savings and efficiencies for the long term.Nicholas Fioravante is vice president of engineering and technical consulting at Arlington, VA-based EMCOR Facilities Services, a core business of EMCOR Group Inc. (www.emcorgroup.com).

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