Under what condition can the Roof Team begin vertical ventilation?

Vertical ventilation is a crucial tactic used by fire services to improve interior conditions during firefighting operations. The correct condition for the Roof Team to begin this operation is after exterior hoselines have been shut down. This is vital because maintaining an effective flow of water onto the fire from the exterior is important for controlling the fire's spread and intensity.

When exterior hoselines are active, they help to cool the fire, reduce the heat in the structure, and control smoke movement. If vertical ventilation is initiated while these hoselines are still operational, it can lead to a dangerous situation where the flow path of smoke and heat is altered, potentially causing backdrafts or flashover. Therefore, the sequence is critical for ensuring the safety of both firefighters and any occupants in the building.

By waiting until the exterior hoselines are shut down, the Roof Team can establish a safer environment for conducting vertical ventilation, allowing for effective smoke and heat removal without compromising the safety of the rescue and firefighting operations taking place inside the structure.