Spreading the Word that Stops the Spread of Fire: Close Before You Doze

Full-Scale Experiments Show The Life-Saving Difference of a Closed Door During a Fire

Fire Safety
November 6, 2017

360 image of two bedrooms after a fire, one with the door open and one with the door closed

The UL Firefighter Safety Research Institute (FSRI) conducted a full-scale experiment inside of a 1,200-square-foot ranch style (single-story) house to demonstrate the importance of closed doors as a passive fire protection measure. The experiment took place at the Delaware County Emergency Services Training Center in Sharon Hill, Pa., where UL FSRI had constructed the model home for other fire research.

During the experiment, the doors to two bedrooms were closed, while a third bedroom’s door was left open. The fire, set in the living room, was allowed to burn until all fuels and oxygen had been consumed keeping it from being able to grow until a new source of oxygen could be introduced (ventilation limited). At this point the front door was opened. Approximately ten minutes after ignition, the fire was completely suppressed with water. Within that time, levels of heat, oxygen and other gases all reached life-threatening levels in the room with an open door while the rooms with closed doors maintained conditions that were far more survivable.

Temperature and carbon monoxide measurements made 4 ft above the floor from the living room, hallway, open bedroom, and closed bedroom are included in the table below.

table showing comparisons of temperatures and carbon monoxide measurements during a fire

*Before and After Images of the Living Room.*

living room

living room destroyed after a fire


living room after a fire

*Before and After Images of the Open Bedroom.*

Bedroom with door open

Bedroom with door open after a fire

*Before and After Images of the Closed Bedroom.*

bedroom with door closed before a fire

bedroom with door closed after a fire