What is one risk associated with bowstring and tied arch roofs during a fire incident?

Bowstring and tied arch roofs present a unique structural risk during a fire incident due to their design. These roofs are constructed using arches and tension members that can be compromised under heat stress. When exposed to extreme temperatures from a fire, the materials that make up these roofs can weaken, leading to a potential collapse.

The risk of falling through the roof arises because the integrity of the structure is diminished as the fire progresses. Fire can cause the roof materials to lose their strength and load-bearing capabilities, increasing the danger for firefighters who are operating above and may not realize how weakened the structure has become. Therefore, this specific architectural design requires extra caution when conducting operations in or around buildings with such roofs during a fire incident.

Other risks, such as smoke inhalation or issues related to roof ventilation failures, while significant concerns, do not specifically highlight the structural failure aspect that is critical in the context of bowstring and tied arch roofs during a fire.