Experts Explain Flashover and Backdraft Fire Hazards
A deadly July 2026 fire at Na Ladprao Brewery killed 27 people, prompting fire experts to explain how flashover and backdraft—two explosive phenomena occurring in enclosed spaces—can turn small fires into deadly explosions within seconds.
Following the deadly fire at Na Ladprao Brewery in the early hours of 13 July 2026, experts have highlighted the dangers of flashover and backdraft—two fire phenomena capable of turning an enclosed blaze into a deadly explosion within seconds.
The blaze claimed 27 lives and left 71 others injured. Video footage captured during the incident showed flames violently bursting from the venue's entrance, with initial speculation suggesting that gas accumulated inside the enclosed kitchen area ignited, triggering a powerful fireball.
According to information published by the Samsen Fire and Rescue Station, the two phenomena are among the most dangerous hazards firefighters face.
What is flashover?
A flashover occurs when combustible gases and vapours generated by a fire accumulate inside an enclosed space. Heat and smoke collect beneath the ceiling, and as temperatures continue to rise, intense radiant heat spreads downward.
Eventually, combustible materials throughout the room release flammable gases until they reach their auto-ignition temperature, causing nearly everything in the room to ignite simultaneously in a matter of seconds.
Fire gas ignition
Fire gas ignition occurs when flames reach accumulated flammable vapours that already contain enough oxygen to ignite. These vapours can travel through ventilation ducts, utility shafts and other openings, spreading into different parts of a building. They may accumulate above ceilings, beneath staircases or in concealed spaces, where they can ignite instantly if exposed to a spark.
What is backdraft?
A backdraft is an explosive fire event caused when fresh oxygen suddenly enters an enclosed area where a fire has consumed most of the available oxygen but remains extremely hot. Also known as a smoke explosion, the phenomenon occurs when a door, window or other opening allows air to rush into the room. The incoming oxygen mixes with hot combustible gases, leading to an explosive ignition.
Warning signs of an impending backdraft
Fire authorities say several warning signs may indicate that a backdraft is about to occur:
- Thick, dense black smoke - Smoke moving in and out through cracks around doors and windows - Smoke being forced out under pressure - A small, tightly enclosed room or building with poor ventilation - Extremely hot walls or building surfaces
What happens before a backdraft?
Before a backdraft occurs, smoke may appear to pulse in and out through openings while the room fills with superheated gases, carbon monoxide and other flammable vapours. When a door is opened, pressurised smoke rushes outward as cooler outside air is drawn in near floor level. The fresh oxygen gradually mixes with carbon monoxide and other combustible gases before reaching the remaining flames. Once the mixture reaches its ignition range, the fire rapidly reignites, travelling back toward the incoming air supply.
