Which roofing system is composed of metal sheets over joists with an adhesive that liquefies when heated, trapping gas and hindering firefighting access?

• A. Wood Construction
• B. Metal Deck Roof Fire
• C. Cast in Place
• D. Pre-Cast

Answer: (B)

The main idea here is how certain roof types behave in a fire and how that affects firefighting access. In a metal deck roof system, metal sheets are laid over joists and bonded with an adhesive that, when heated, can liquefy. As the fire heats this adhesive, it flows and traps gases under the roof. Those trapped gases create pressure and hidden pockets, making ventilation difficult and increasing the risk of hazardous conditions for firefighters working above or inside the structure. The combination of a gas-trapping, heat-activated adhesive and a metal deck can also complicate access and rapid assessment, since the roof may appear intact from above while dangerous conditions build underneath.

Other roof systems described—wood construction, cast-in-place concrete, or pre-cast concrete—do not rely on a heat-liquefying adhesive that traps gases under a metal deck, so they don’t present the same specific hazard to ventilation and above-roof access.