Our Investigation methodology
Fire & Explosion Origin, Cause and Circumstances Investigation.
The "NFPA 921" Guide — the international reference.
The "NFPA 921" — Guide for Fire and Explosion Investigations — is the international methodological reference for "Post-Fire" Investigation. Published by the National Fire Protection Association, it structures the scientific approach into six steps, from referral to report.
FireLab Pyrénées™ has applied this methodology to all of its Investigation engagements for more than 15 years. Every case follows the same approach — no shortcuts, no speculation.
The cause of a fire is not assumed — it is demonstrated. It is Established when the physical evidence confirms it, or remains Undetermined when the findings do not allow a conclusion. It is never Probable.
Six steps, one single rule: the facts.
The scientific approach of "NFPA 921" unfolds in six consecutive and inseparable steps. Each one feeds the next. At every step, physical facts take precedence over intuition.
Recognising the need.
Receipt of the engagement. Identification of the referral framework — Court, Insurer, Mutual insurer or Private individual — and of the first technical data available. This first step sets the legal and technical context of the intervention.
Definition of the scope of intervention, the timeline, the arrangements for accessing the loss scene and the parties involved. Methodological rigour begins here: knowing your framework in order to apply it.
Defining the problem.
Initial examination of the loss scene. Assessment of access conditions, structural stability, residual hazards and the chronology of the rescue operations that preceded the investigator’s arrival.
Preservation of the elements relevant to the investigation. Marking out of the areas to be protected, identification of fragile evidence liable to disappear. The scene is never frozen — every passing hour alters the traces.
Data collection.
Methodical recording of Combustion Traces and Fire Effects - TCEF. Photographs, measurements, sketches, samples and sealed exhibits, remains packaged for laboratory analysis if necessary. Every item is documented, located, preserved.
Gathering of witness statements, examination of technical documents — drawings, manuals, maintenance reports, safety registers. Collection is exhaustive: at the time of collection, no one knows which items will prove decisive later on.
Data analysis.
Cross-referencing and interpretation of the collected data in the light of fire science — fire dynamics, heat transfer, propagation mechanisms, behaviour of materials. The analysis draws on the physical understanding of the loss.
Comparison between physical data and witness statements. Physical evidence prevails. A statement that contradicts the findings must be questioned again — not the other way round. The technical truth is built by cross-checking.
Testing the hypotheses.
Formulation of cause hypotheses in the light of the findings. Methodical elimination of each one through confrontation with the physical facts. Determination of the Area of Origin — the broader zone where the fire started — then of the Point of Origin — the precise location.
Only the hypothesis confirmed by the findings is retained. Any alternative hypothesis that cannot be ruled out keeps the cause classified as Undetermined. It is this discipline that distinguishes the scientific approach from intuitive reasoning.
The conclusion.
Formalisation of the approach in a detailed investigation report: findings, Combustion Traces and Fire Effects - TCEF, analysis, technical reasoning, hypotheses examined and conclusions consistent with the "NFPA 921" methodology. Every conclusion is traced back to its physical source.
The cause of the fire is Established, or classified as Undetermined when the evidence does not allow a conclusion. It is never Probable. It is this rigour that gives the report its technical and legal value.
International standards of forensic investigation.
FireLab Pyrénées™ aligns with the international standards for Fire & Explosion Origin, Cause and Circumstances Investigation. Active membership in the two leading professional associations of fire and explosion investigators.
International Association of Arson Investigators
The leading international organisation for investigators of incendiary and accidental fires. Founded in 1949.
Active member · New Jersey Chapter
European Association of Fire Investigators
European branch of the IAAI. A continent-wide network of post-fire investigation experts.
Active member · IAAI Europe
