When the 2026 Boyle Heights cold-storage warehouse fire was finally knocked down, the operator and the owner of the building's rooftop solar array were already giving conflicting accounts of how it started. According to news reports, the operator, Lineage, said it believes the fire began on the roof while the array's owner, Altus Power, was conducting testing; Altus Power has said the cause "has yet to be determined." Fire officials have not announced an official cause and have said only that the fire originated on the rooftop. Both sides understand the same thing: whoever the fire origin and cause expert ultimately blames will likely be whoever pays.
That surprises newer attorneys and claims professionals. The damages are easy to total. The fight is rarely about how much was lost. It is about where the first flame appeared and what made it appear there. Answer that, and the duty, the breach, and the chain of causation line up behind it.
The origin-and-cause finding is the case, not a detail of it
In a building fire, two questions sit at the center of liability. Where did the fire start (origin), and what ignited it there (cause)? Everything downstream depends on those answers.
The Boyle Heights matter illustrates the point, with the important caveat that no cause has been determined and the following are only hypotheticals. If an investigation were to place the origin on the rooftop and tie the cause to the solar equipment, the parties associated with that equipment and their insurers could be exposed, and the theory might sound in negligent installation or a defective component. If instead the origin were a refrigeration compressor, an aging electrical panel, or stored materials inside the cold-storage envelope, the exposure could shift toward the operator, its maintenance vendors, or an equipment manufacturer. Same building, same loss, a potentially different set of defendants. Which of these (if any) the evidence supports is exactly what an investigation has to establish.
That is why the origin-and-cause determination carries the case. Spoliation arguments, subrogation targets, the choice between a negligence and a products theory, even which experts you retain next, all branch off it. A weak or rushed origin opinion does not hurt one element of your case. It puts the whole structure at risk.
What NFPA 921 actually requires of an investigator
The standard that governs this work is NFPA 921, the Guide for Fire and Explosion Investigations. It is the framework opposing counsel will measure your expert against, and the one a court will reference when it weighs whether an opinion is reliable. You do not need to master it to use it, but you should know what it demands.
NFPA 921 requires the investigator to use the scientific method rather than a hunch formed at the scene. The expert collects data, develops hypotheses about origin and cause, then tests each hypothesis against the physical evidence, trying to disprove it rather than confirm it. A defensible expert can walk you through the hypotheses they considered and explain, with evidence, why they rejected the alternatives.
The standard also presses investigators to be honest about uncertainty. When the evidence does not support a single cause, the proper classification may be undetermined. That word unsettles a client who wants a clean target, but an expert who reaches for it when the data is genuinely ambiguous reads as more credible than one who forces a conclusion. In a contested matter like a disputed warehouse fire, the investigator willing to say what the evidence does not show is the one who survives a Daubert challenge.
Cold-storage and rooftop-solar fires raise their own complications
A cold storage fire investigation is not a routine structure fire. Refrigerated warehouses combine heavy electrical loads, compressors and condensers running constantly, insulated metal panels that can hide fire spread, and ammonia or other refrigerants that change how a fire behaves and how safely investigators can even enter. Burn patterns that would point cleanly to an origin in an ordinary building can be distorted by concealed spaces and unusual fuel loads.
Add a rooftop solar array and the picture gets harder. Photovoltaic systems carry direct-current wiring that stays energized in daylight even after the building loses power, which affects both firefighting and the post-fire scene. Determining whether a solar component was an ignition source, or simply something that burned because the fire reached it, calls for an investigator who understands these systems, not one guessing from a distance.
For an attorney, the lesson is to match the expert to the building. The right fire cause investigator for a disputed solar-versus-refrigeration loss has handled commercial electrical fires, understands photovoltaic systems and refrigeration equipment, and can hold those opinions together under cross-examination. General competence is not competence in this kind of fire.
What to demand before you rely on an opinion
You can pressure-test an origin-and-cause expert long before a deposition.
Ask how soon the expert can reach the scene and whether evidence is being preserved for all interested parties. Origin-and-cause work degrades fast, and a joint, documented examination protects you against a spoliation fight later.
Ask the expert to state the origin, the cause, and the basis for each, then to list the hypotheses they ruled out and why. An expert who can defend a conclusion but cannot explain what they rejected has not applied the method NFPA 921 calls for.
Ask directly whether the evidence supports a single cause or whether parts of the analysis remain undetermined. You want that answer in a quiet conference room, not for the first time on the stand.
Ask about documentation. Photographs, scene diagrams, sample collection, and a clear report let a second expert follow the reasoning, and let you anticipate where the other side will push.
The takeaway
In a contested loss like the Boyle Heights warehouse fire, where the cause has not yet been determined, liability will turn on a defensible answer to where the fire started and what caused it. That answer is only as strong as the investigator behind it, the rigor of their method, and their candor about what the evidence does and does not prove.
None of this is legal advice; it is a way to build the technical foundation of a fire case before you commit a theory of liability. When you reach the point of retaining or evaluating one of these experts, compare credentials, fire and electrical experience, and courtroom track record side by side. Browsing the origin-and-cause and fire investigators listed in this directory is one place to start.