Fire Containment—What Does it Mean?

During a fire, we often hear that the fire is contained by some percentage number, such as 10 percent contained or 80 percent contained. What does this mean?

Containment is the perimeter that firefighters create around the fire to keep it from spreading. The containment perimeter can be any physical barrier—constructed or natural—that stops the fire from passing a certain point, such a trenches, rivers, or burned patches of land. The blaze can continue to burn within the containment perimeter.

When the fire is controlled, it means the fire can’t spread or cross the containment line. Firefighters have removed any unburned fuels and cooled down all hot spots adjacent to the containment lines to the point they can be reasonably expected to hold.

A fire is considered “out” when no hot spots are detected within containment lines for at least 48 hours.