Rollover is a stage of a structure fire

Structure fire

A structure fire is a fire involving the structural components of various residential buildings ranging from single-family detached homes and townhouses to apartments and tower blocks, or various commercial buildings ranging from offices to shopping malls...

 when fire gases in a room or other enclosed area ignite. Since heated fire gases, the product of pyrolysis

Pyrolysis

Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible...

, rise to the ceiling, this is where a rollover phenomenon is most often witnessed. Visually, this may be seen as flames "rolling" across the ceiling, radiating outward from the seat of the fire to the extent of gas spread.

Rollover is not the same as flashover

Flashover

A flashover is the near simultaneous ignition of most of the directly exposed combustible material in an enclosed area. When certain organic materials are heated they undergo thermal decomposition and release flammable gases...

, although it may precede it, and the terms may be confused. In the case of rollover, only gases present in the room, not the room contents, ignite.

External links

• Term of the week: Flameover
• Pictures
  • http://www.ci.frisco.tx.us/departments/fire/PublishingImages/Training%20Center%20-%20Living%20Room%20Flashover.jpg
  • http://www.firecontrolservices.co.uk/large_imgs/structural3.htm
  • http://www.nyc.gov/html/fdny/images/home_specific/feature_photos/2009/379x250_031909a2.jpg