The Layman Method was designed for a different era, one with limited understanding of fire behavior and fewer options for coordinated rescue. The Iowa Method represents a modern shift in fireground philosophy: from steam production to thermal cooling, from external suppression to interior survivability, and from indirect smothering to coordinated entry and life safety. This is not merely a tactical preference; it’s a fundamental evolution in how we fight fires and save lives.
As fire science and structural firefighting tactics evolve, so must our methods on the fireground. Among the most significant shifts in fire suppression philosophy is the transition from the Lloyd Layman Method, developed in the mid-20th century, to the Iowa Method, introduced in the 1990s and grounded in modern research. While both techniques were created to address fires in enclosed spaces, the Iowa Method has emerged as the superior approach due to its scientific foundation, enhanced safety for occupants and firefighters, and increased operational effectiveness.
The Iowa Method was developed through research led by the University of Iowa in collaboration with multiple fire departments. It is built upon an advanced understanding of compartment fire behavior, specifically the dynamics of heat, gas layering, flashover potential, and smoke movement. This method uses short, pulsed bursts of water aimed at the hot gas layer near the ceiling, delivered from within the structure. The objective is not to extinguish the fire immediately but to cool the thermal environment, delay or prevent flashover, and improve conditions for interior search and rescue.
Developed during World War II, the Layman Method uses an indirect fire attack, introducing a fog stream through a window or door without entering the structure. The mist rapidly converts to steam, theoretically displacing oxygen and smothering the fire. While this approach was effective in enclosed environments like ship cargo holds, it poses serious risks in residential or commercial structures: excessive steam can cause fatal burns to trapped civilians, visibility is significantly reduced, hindering interior navigation, search and rescue are delayed until after suppression, and it does not account for modern construction or synthetic fuel loads.
The Iowa Method corrects many of Layman’s shortcomings while introducing several critical life-saving benefits. Firefighters enter in a coordinated manner and apply water directly to the gas layer, allowing them to manage the thermal environment rather than just suppress flames from the outside. Cooling the overhead gas layer improves visibility, reduces radiant heat, and buys valuable time for rescuing trapped occupants. By lowering the temperature of the upper gas layer, the Iowa Method significantly reduces the risk of flashover, the deadliest threat in a structure fire. Short, controlled water bursts prevent over-application, reducing water damage to property and minimizing steam production, creating a safer environment for both civilians and firefighters.
Under the Layman Method, a 95 GPM nozzle delivering just 47.5 gallons of water can generate over 80,000 gallons of steam. That steam can quickly fill a room, potentially injuring or killing civilians trapped inside. In contrast, the Iowa Method might use only 16.5 gallons across five quick pulses, enough to cool the compartment without flooding it. The resulting water accumulation is about 0.26 inches, just enough to bring down the temperature while preserving survivability.
The transition from the Layman Method to the Iowa Method represents more than a change in tactics. It reflects our commitment to science, safety, and saving lives. By adapting to modern fire behavior and incorporating evidence-based strategies, today’s firefighters are better equipped than ever to protect life and property.
José Musse, Director of Fire Training Center of Peru
New York City
DESASTRES.org
