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Forensic Engineering: Expert Tips From The Trenches

Sept. 25, 2021
NEW SERIES: One veteran engineer and experienced expert witness shares his insights about what to expect and how to keep cool if you are called to testify in court.


The concept of “forensic”, at least in the U.S., seems commonly to be associated exclusively with criminal matters. However, as defined by Merriam-Webster, it means “belonging to, used in, or suitable to courts of ‘judicature’ or to public discussion and debate”.

As it turns out, there are ample situations where construction defects and other building-related matters are best (or only) resolved through the use of forensic investigative and analytical skills in the practice of engineering, be it manufacturing, design, construction or even operations and maintenance of buildings and building infrastructure systems.

One could easily write a book on the subject, and some day, I may well add such a book to my list of publications. But for the purpose of this new series of articles, I will limit our treatment of the subject to a short list of topics I find fascinating or little-understood.

As a member of the HPAC Editorial Advisory Board for over 20 years, and as a fellow of and the founding chair of the first US chapter of the British Chartered Association of Building Engineers (CABE), it seemed appropriate to share some of my experience as a forensic engineer and as an expert witness in nearly 70 cases. To do so, I will first provide here some vignettes addressing what I consider to be truisms I have discovered in this field of endeavor, plus one case study now, with more to come later.

The Nature of the Engineer

Having practiced forensic engineering for a few decades, I have come to realize that the nature of engineers, themselves, is a significant factor in addressing legal matters.

The deposition (particularly as practiced in the U.S. legal system) is a venue in which the engineers’ inherent nature seems to most come to light. The nature of engineers seems to be mostly universal, in that engineers are problem solvers at heart, and they also seem to also have a predilection for being loquacious.

The problem arises when a question is posed to the engineer as expert witness, that is incomplete or illogical, or in some other way flawed. It is the nature of engineers to want to “fix” the question so that the truth of the matter in question can be properly explored and revealed. While this might seem to be a laudable endeavor, it is in fact quite problematic in legal proceedings.

Lawyers are generally not knowledgeable of technical matters that are material to a case, and may not ask a question in a proper fashion, or (as the author has regularly experienced) intentionally “slaughter” a question so that the expert’s testimony in deposition may be used to later impeach the expert’s testimony at trial. “Mr. Jones, were you lying during your deposition, or are you lying now?” is the opposing counsel’s possible question to the witness at trial, when the trial testimony appears to contradict that testimony given during deposition.

This is further problematic as the counsel who has engaged the expert may very well not realize that opposing counsel is employing such a tactic, even if unintentionally. While the expert may have taken an oath (or affirmed) that their testimony “shall be the truth, the whole truth, and nothing but the truth”, as a matter of practicality the forensic engineer providing expert testimony can (and should) really only answer questions asked, and eschew amplification, except where it may be particularly material. 

The Unanswerable Question

In the movie “My Cousin Vinny”, Miss Mona Lisa Vito is presented to the court by defense counsel as an expert on automobiles. The prosecution is doubtful, and asks to voir dire the proposed expert to determine her qualifications. In the process, the prosecutor asks Miss Vito what the ignition timing would be on a 1955 Chevrolet with a 327-cubic-inch engine. Miss Vito responds that she cannot answer the question, as it is a “trick” question. Asked by the judge to explain why it is a “trick” question, she observes that the 327 V8 engine was not provided in Chevrolet sedans until 1964, and therefore there is no answer to the question as posed.

Now, in this example the fact that the question was unanswerable was fairly easy to explain. However in more complicated or obscure matters, that a question assumes facts not in evidence may not be so obvious. I like to cite this as a clear example of an unanswerable question: “What is the color of the letter nine?” 

The wise forensic engineer will make it a practice under oath to listen very, very carefully to questions posed by opposing counsel. My practice is to ask the suspected unanswerable question to be repeated, then repeated one additional time, before adjudging the question to be unanswerable. And then to respond along the lines of, “The question makes no sense whatsoever, and that attempting to answer such a question would be based entirely on supposition, so no answer is therefore offered.” 

The forensic engineer providing such a response should be prepared to be treated potentially with disrespect, anger, and even accusation of violating their oath – but should adamantly refrain from attempting to answer the unanswerable. Having been to war, I have found it fully possible to withstand such aggressive questioning.

Curious Trio: Special Masters, Mediators, Arbitrators

Virtually all tort cases settle out of court. A good part of that is because our courts are busy, and the cost of going to trial is indeed consequential. As a result, a number of non-judicial means of settling legal disputes are employed. Here is my experience with Special Masters, mediators and arbitrators:

Special Masters are typically retired judges or lawyers, who want to keep their hand in the process, but no longer are involved in the daily grind of executing the law.  A couple of things seem to be true about Special Masters. Their job is to see if the parties to a dispute can find a resolution without going to trial. Going to trial is very, very expensive. I think that first of all, the goal of a Special Master seems to be to see if an injured party can be made whole. The process involves getting the parties to share information without necessarily going through the formal legal process of discovery. Once a goodly amount of information is shared, the Special Master then meets with each of the parties individually, to assess their position and its strength. Subsequently, the Special Master will then meet with the parties en masse. This makes for an interesting dynamic. 

One thing, in particular, that I have noticed is that at times one party or the other has a somewhat inaccurate sense of the strength or validity of their case and pursues it with unjustified vigor, seemingly ego-driven to win. Often contributing to this is their expert's apparent belief that it is OK to assert claims of damages that are patently inconsistent with the facts of the case. In one $30-million claim, for example, experts claimed conditions that did not exist and actually cited building codes that were not yet in effect at the time the construction work was permitted.

In another case, a defendant’s expert claimed that our own expert team had opened access panels on rooftop units during a site survey and then left them open upon the completion of our survey. In fact, the defendant’s building maintenance staff had opened all panels (we were totally hands-off, for good reason). The other expert was not even present when the survey was conducted, yet claimed firsthand knowledge of our actions.

Another frequent phenomenon in these cases is what I call "the nose count." In my experience, it seems it is only the people with insurance that end up paying the bill when a lawsuit is initiated. When a settlement conference is held by a Special Master, all the defendants and their counsel are all brought together in a big conference room. The Special Master will say something like, "Well, we have a million-dollar claim. There are 10 defendants in the room. That means you are each 'in' for $100,000."

Then the Special Master will ask, "Who doesn't have insurance coverage?" Perhaps five defendants will raise their hands, and the Special Master will tell them something like, "You can go''. Then, after half the room has cleared, the Special Master will clear his throat and say, "OK, now you are each 'in' for $200,000." And the conference will continue.

I swear, this, or something very much like it, has happened on almost every one of my cases. It seems, in civil suits, that the ability to pay is the only thing that determines whether you're culpable. The obvious conclusion is that carrying insurance, in many circumstances, is like hanging a sign around your neck that says "Sue me."—and that the only sensible course is to not carry insurance—which runs contrary to the "conventional" wisdom.

My experience with mediators has been along somewhat different lines. What I have seen is that a particular mediator strategy is to try to convince each side of the case that their side of the dispute is weak and will result in their losing, should the case go to trial. In one specific case,  the mediator acted essentially as an insulting bully, apparently in hopes of convincing everyone that their position was hopeless. I countered this by successfully demonstrating to my counsel a technique I call “paper dolls” (a visually graphic method of presenting the complex information in the case to see the likely ability of jurors to understand it).

Finally, arbitrators are yet another horse of a different color.  While non-judicial, arbitration is typically binding, and most often includes recovery of all legal costs by the prevailing party. Arbitration is definitely a form of “rolling the dice” and may be conducted by a single arbitrator, or a panel of, say, three arbitrators. Unlike most of the processes conducted by Special Masters or mediators, everything in arbitration is done under oath, so a forensic engineer as expert witness really must have their act together and choose their words wisely.

Curiously, I have found it not unusual at all for even highly-regarded forensic engineers to state views that are not at all “expert” opinions, but really just their personal opinions that are often quite unfounded. While the proceedings are quite formal, there is a widely held belief that arbitrators, much like Solomon, generally choose to “split the baby”.

CASE STUDY: The Wayward Condenser Water Pipe

This case involved a city center high-rise of some 50+ stories, with a failed tenant improvement project on the 35th floor. The tenant was an international financial trader who had a fairly significant server room, and part of the tenant improvement was to run 3-in. copper condenser water lines from the pair of 20-in. condenser water pipes. This project was done as a design/build job, with a notable consulting firm taking on the design task.

About 18 months after the project was complete, one of the 3-in. lines separated at a fitting, and because there was some 15 or so stories of static head above the break, the condenser water sprayed against the sheetrock shaft wall, penetrated the sheetrock and flooded the floor. The tenant was not amused. But there was also much more. 

Repairs were made and the tenant’s business grew. So the tenant leased another floor, immediately below the first. Some 18 months later, the same piping joint failed again! Now the tenant was hopping mad, and a lawsuit proceeded apace. Now, since it was the plumber’s work that failed, they were considered the prime suspect. But a number of factors contributed to the failure, as follows:

1. Means and methods. Brazing of the copper joints was specified, and originally employed. But upon pressure testing of the new piping, one joint did not pass. It was re-made using soft solder. (Probably not the best choice.) However, the pressure capacity of a silver solder and a soft solder joint is not that much different. But of course, the soft solder does not have the same physical strength as silver solder;

2. More means and methods. Apparently, because the general contractor did not want the cost of a large access door to the piping and shut-off valves, the fitter was left with only a 12-in.-x-12-in. access door to work through to do his joints in the shaft. Now, were this a half-inch or even a one-inch pipe, that might have worked as making up a small joint allows the fitter to uniformly heat the entire joint before applying the solder. However, a 3-in. joint is a horse of a different color. To sweat a large joint one must begin at the bottom and only heat a portion of the joint at a time. One makes a solder “dam” at the bottom, then works one’s way around the pipe applying heat and solder until you arrive again at the bottom of the joint. Now, trying to do that to a joint that is just inside a very small access door is not physically possible. So, left with no other option, the fitter heated the entire joint uniformly and fed the solder in at the top of the joint. As can be seen in the photo, a funny thing happened. The solder mostly ran to the bottom of the joint, leaving a scant,  less-than ¼ inch of solder in the space between the top of the section of pipe and the cup of the joint coupling. Still, it held pressure just fine – for about 18 months, until another factor came into play;

3. Movement of risers without design accommodation. As it turns out, the large condenser water risers were of heavy steel pipe, which was supported by a stand in the basement of the building. In addition, the building employed a waterside economizer for “free cooling” with condenser water in colder weather. What this meant was that the change in temperature in the pipe would cause the point of connection of the 3-in. branch lines to rise and fall by about 2 inches. Now, the two large risers were in line with each other along the direction that the branch lines had to go. So, the 3-in. branch line on the far pipe had three elbows in it in order to get around the other riser.  However, the other branch line was a straight shot off the riser to provide about a 12 foot straight run to the nearby hallway, where both lines turned 90 degrees to proceed to/from the server room. We all know to provide offsets or expansion loops in long runs of pipe that experience significant thermal expansion. Unfortunately, in this case it appeared that a draftsman/designer was left to design the job, with the P.E. stamping and signing the plans following what was likely a very cursory review of the permit plans. An unfortunate shortcoming in the “professional” services provided on the project. Had a couple of turns been provided in both branch lines, a flexible coupling in each, or even one or two flexible grooved fittings, the whole problem could likely have been prevented.


Accidents are known to occur when multiple, relatively innocuous circumstances come together. In this case, some actual engineering, or wiser employment of means and methods could have dodged what was a truly horrible experience for a building owner and its high-flying tenant.


Based in West Sacramento CA, the author James Waltz is president of Energy Resource Associates Inc., specializing in turnkey forensic examination and engineering of infrastructure renewal for existing-building mechanical, electrical, control, and structural systems. He is a member of the Association of Energy Engineers Hall of Fame, and a fellow of the first U.S. chapter of the Chartered Association of Building Engineers (CABE – UK), which he chairs. Waltz joined the HPAC Engineering Editorial Advisory Board in 2000. Contact: [email protected]