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Lightweight truss construction, often used in modern residential and commercial buildings, poses a significant risk during fire operations. Trusses made of small-dimension lumber or lightweight metal can fail quickly when exposed to heat because they rely on multiple fasteners and adhesives rather than mass. NFPA standards and Firefighter II training emphasize that lightweight trusses may collapse in as little as 5 to 10 minutes of fire exposure, compared to heavy timber or reinforced concrete, which can withstand fire much longer. This makes early recognition of construction type critical for firefighter safety. Heavy timber has inherent fire resistance due to its mass, and reinforced concrete maintains strength for a longer period. Fire-resistive construction (Type I) is specifically designed to withstand high heat without structural failure. Therefore, recognizing lightweight truss systems during pre-incident planning and size-up is essential to avoid entrapment and ensure effective tactical decisions on the fireground.