When the Los Angeles Department of Building and Safety opened a probe into an allegation of unpermitted construction at the warehouse destroyed in the 2026 Boyle Heights fire, news outlets reported that the building's cause-of-failure picture was still unsettled. According to CBS News, the unpermitted-work claim was listed in city records as "under investigation," the fire's cause had not been officially determined, and the companies involved publicly disputed what happened. That kind of unresolved scene is a familiar starting point for the question facing the attorneys watching such a case: not "what burned" but "why, and who is responsible for the why." A building can fail because something was designed or built wrong. It can also fail because work was done that no inspector ever saw, no permit ever covered, and no code ever signed off on. Those answers point to different defendants under different legal theories, and after the structure is gone, the reliable way to tell them apart is construction defect forensic analysis.
The difference matters long before trial. It shapes who you put on notice, which insurers owe a defense, and whether you are arguing negligence, code violation, or both. This post walks through how forensic structural and code-compliance experts reconstruct a collapsed or burned building, and how they keep a defect theory and a code-violation theory from being quietly merged.
Defect Versus Code Violation: Two Theories That Look Identical From the Outside
To a jury, a failed wall looks like a failed wall. Forensically, that wall can tell at least two stories. The first is a defect: the structure was permitted, designed, and inspected, yet something in the materials, the connections, or the load path could not carry the conditions it faced. The second is a code violation, often tied to unpermitted construction: someone added a mezzanine, rerouted a load, enclosed an exit, or modified the electrical without a permit, and that hidden work changed how the building behaved under stress.
The two theories point at different parties. A genuine defect can implicate a designer, a manufacturer, or a contractor who followed the plans but built them poorly. Unpermitted work usually points at an owner, a tenant, or whoever directed changes outside the inspection process. A forensic structural engineer investigation assigns the failure to one column or the other, and a careful expert resists merging them just because both are present. In a complex building, both can be true at once, and the apportionment between them is often the most contested number in the case.
Reconstructing a Building That No Longer Exists
The hardest part of construction defect forensic analysis is that the evidence is often damaged, collapsed, or burned by the time anyone asks questions. Forensic engineers rebuild the structure on paper and in models before they can explain how it failed.
That reconstruction draws on several sources, cross-checked against each other:
- The permitted record. Original plans, permit history, and inspection sign-offs establish what the building was supposed to be. Gaps in that record are themselves evidence.
- The physical remains. Debris fields, fracture surfaces, fastener condition, and char patterns show the sequence and direction of failure.
- The as-built condition. Photographs, prior surveys, satellite or street imagery, and witness accounts establish what was actually there, which is frequently not what the permits describe.
When the as-built condition diverges from the permitted record, the engineer has found the seam where an unpermitted construction expert witness becomes relevant. A modification that never appeared on any plan is, by definition, work no engineer reviewed and no inspector approved.
How a Code-Compliance Expert Frames the Unpermitted Question
The permit and inspection process is the mechanism that checks a building's design against the applicable code and verifies it in the field. When work skips that process, two things happen: the work itself may violate the code, and the absence of review removes the safeguard that would have caught a problem.
A code-compliance expert identifies which edition of the building, fire, and electrical codes applied, what those provisions required, and where the as-built condition departed from them. The careful version of this analysis stays disciplined about causation. A code violation is not automatically the cause of a failure. The expert has to connect the specific deviation to the specific mode of failure, not offer a violation as a stand-in for fault. An attorney leaning on this testimony should expect to be asked, by the other side and by the court, whether the violation drove the outcome or merely existed alongside it.
Why the Two Theories Have to Stay Separate
In a major structure fire, there is a real risk of letting "it was unpermitted" do the work that "it was defective" should be doing, or the reverse. The two feel interchangeable in a settlement conference. They are not interchangeable on the stand.
If you argue defect, you accept that the work went through the proper channels and still failed, which directs liability toward design and construction quality. If you argue unpermitted code violation, you argue that the proper channels were bypassed, which directs liability toward whoever made that choice. Blurring them invites a defense expert to pull the theory apart and a jury to distrust the presentation. The strongest forensic work names each contributing cause, supports each with its own evidence, and assigns weight between them instead of collapsing everything into a single accusation.
This is where the qualifications of your expert matter. Reconstructing structural failure, reading char and collapse patterns, and interpreting code editions are related but distinct competencies. Some investigations need a forensic structural engineer and a separate code-compliance specialist, and matching the expert to the actual question is part of building a credible record.
The Practical Takeaway
After a catastrophic building failure, resist the urge to settle on a single narrative early. Treat "defective" and "unpermitted" as separate hypotheses, preserve the permitted record and the physical evidence before they degrade, and bring in forensic expertise while the scene still holds answers. The engineer who can distinguish a true defect from a code violation, and explain to a jury exactly how they know, is the one who keeps your theory intact under cross-examination.
If you are scoping an investigation and want to compare forensic structural engineers and code-compliance specialists by discipline and region, you can browse listed experts in The Forensic Expert Directory to start that conversation.
This article is educational and is not legal advice.