What roof assembly consists of metal sheets laid over steel bar joists with an adhesive that liquefies under heat, trapping gas under the roofing and making access and extinguishment difficult?

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

Answer: (D)

The main idea here is how certain roof assemblies behave when exposed to fire, specifically metal deck roofs that use an adhesive layer between sheets. In this type of construction, metal sheets sit on steel bar joists and are fastened with an adhesive that can liquefy when heated. As heat from the fire increases, that adhesive turns soft or liquid and traps pockets of gas trapped under the roofing. Those trapped gases make access for firefighters and extinguishment from the inside much more difficult, because you have hidden fire and pressure under the roof, and the roof itself may be unstable or buckle as the adhesive loses its strength.

That’s why this choice describes a metal deck roof fire—the only scenario that involves an adhesive that liquefies under heat and creates trapped gas beneath the roofing, complicating ventilation, access, and suppression. The other options refer to different construction types (wood, poured concrete, precast) that don’t carry this same adhesive- and gas-trapping behavior.