NFPA 921: Guide for Fire and Explosion Investigations is a crucial document that outlines the methodology and standards for conducting thorough and accurate investigations of fires and explosions. Developed by the National Fire Protection Association (NFPA), a nonprofit organization committed to eliminating death, injury, and economic losses resulting from fires and related hazards, NFPA 921 is considered the authoritative guide for professionals in the field. The document is regularly updated to reflect advances in fire science, technology, and investigative techniques, ensuring that it remains a valuable resource for fire investigators, first responders, and insurance professionals alike.

Understanding NFPA 921

NFPA 921 serves as a comprehensive guide for conducting fire and explosion investigations. It provides detailed information on the principles of fire behavior, the systematic process for investigating fires and explosions, and the documentation necessary for accurately determining the cause and origin of an incident.

Key aspects of NFPA 921 include:

  • A. Scientific Method: The guide emphasizes the use of the scientific method as the basis for conducting investigations. This approach ensures that investigators follow a systematic and objective process that relies on observable, empirical, and measurable evidence to draw conclusions.
  • B. Fire and Explosion Dynamics: NFPA 921 covers the fundamentals of fire and explosion dynamics, including ignition sources, fire growth, and fire spread patterns. This knowledge is essential for understanding the behavior of fires and explosions and is critical in determining their cause.
  • C. Data Collection and Analysis: The guide provides instructions for collecting and analyzing evidence from the scene, including the proper handling, preservation, and storage of evidence. It also discusses the importance of interviewing witnesses and gathering information from various sources, such as building plans, permits, and maintenance records.
  • D. Cause Determination: NFPA 921 outlines a systematic approach for determining the cause and origin of fires and explosions. Investigators are encouraged to consider multiple hypotheses and to use the process of elimination to arrive at a final conclusion.

NFPA 921’s Impact on the Fire Investigation Community

NFPA 921 has had a significant impact on the fire investigation community, as it has helped to standardize the methods and techniques used by investigators worldwide. By following the guidelines set forth in NFPA 921, investigators can ensure that their conclusions are based on sound scientific principles and are less likely to be challenged in court. Furthermore, the document has helped to bridge the gap between the scientific and legal communities by providing a common language and understanding of fire investigation methodologies.

Regular Updates to NFPA 921

The NFPA regularly updates NFPA 921 to keep pace with advancements in fire science, technology, and investigative techniques. These updates ensure that the guide remains a relevant and valuable resource for professionals in the field. As the field of fire investigation continues to evolve, it is essential for investigators to remain informed about the latest developments and best practices outlined in NFPA 921.


NFPA 921 plays a critical role in the fire investigation community, providing a standardized approach to conducting thorough and accurate investigations. By adhering to the guidelines set forth in the document, fire investigators can ensure that their conclusions are based on sound scientific principles, ultimately leading to safer communities and more effective fire prevention efforts. As the field continues to evolve, professionals must remain committed to staying informed about the latest updates to NFPA 921 and incorporating these advancements into their investigative practices.


  1. National Fire Protection Association (NFPA) 
  2. NFPA 921: Guide for Fire and Explosion Investigations (latest edition)
  3. International Association of Arson Investigators (IAAI)
  4. National Association of Fire Investigators (NAFI)

Last Updated on April 4, 2023