Which condition could indicate a significant fire risk in a structure?

The presence of large amounts of combustible materials is a significant fire risk factor in a structure because it directly increases the fuel load available in the event of a fire. Combustible materials can include anything from paper and cardboard to wood, textiles, and various plastics. When these materials are present in large quantities, they can facilitate rapid fire spread and potentially accelerate the intensity of a fire, making it more difficult for firefighters to control.

In contrast, the use of non-combustible materials serves to reduce fire risk since these materials do not ignite or sustain combustion. Structural integrity assessments are important for determining the safety and viability of a building but do not inherently indicate fire risk by themselves. Similarly, while the installation of fire alarms is crucial for early detection of fires, it does not reflect the inherent fire risk in terms of existing combustible materials within the structure. Therefore, the accumulation of combustible materials is a clear indicator of heightened fire risk.