Which feature can contribute to building vulnerability during a fire incident?

Lightweight materials significantly contribute to building vulnerability during a fire incident due to their reduced structural integrity under high temperatures. When exposed to fire, lightweight materials tend to fail more quickly than traditional heavy-duty construction materials. For instance, engineered wood products and metal trusses may have diminished fire-resistance capabilities, meaning that the structural support they provide can collapse rapidly, leading to increased danger for occupants and first responders during firefighting operations.

In contrast, steel reinforcement, while potentially threatening in a fire due to the risk of structural failure if not properly insulated, typically has a higher resistance to fire compared to lightweight materials. Open floor plans can affect fire spread and smoke movement but do not directly relate to material vulnerability. Non-combustible barriers are designed to contain fires and slow their spread, thus enhancing safety rather than contributing to vulnerability. Therefore, lightweight materials are notably more susceptible to rapid degradation in the face of a fire, making them a key concern in fire safety and building design.