Cavity barriers are a form of passive fire protection installed in open cavities. This includes the spaces between walls, floors, and ceilings. Closing these gaps prevents flames from moving outside of a contained area.
They perform two functions: keeping flame and smoke out of an unaffected area and trapping a fire in its original compartment.
Cavity barriers are used in both external and internal walls as well as between different levels of a building. They even prevent fires from spreading from one building to another.