Rollover definition: which statement best describes it?

• A. Rollover is flames spreading across the ceiling or roof surface; indicates unstable fire conditions and imminent flashover if not controlled.
• B. Rollover is flames spreading across the floor.
• C. Rollover is smoke drifting toward the exit.
• D. Rollover is water vapor condensing on the roof.

Answer: (A)

Rollover is the flame front moving along the ceiling, where the hot, flammable gases in the upper layer ignite and flames roll across the ceiling surface. This signals that the fire has heated the ceiling layer to its ignition point and that conditions are becoming unstable, with a high risk of flashover if the situation isn’t controlled. It’s a warning sign to reassess tactics and safety.

The other descriptions don’t fit because they involve flames on the floor, smoke moving toward an exit, or water vapor condensing on the roof—none of which capture the ceiling-level flame front that characterizes rollover.