What is the most common state of fuels in structure fires at the start?

The most common state of fuels in structure fires at the start is solids. When a fire ignites in a structure, it typically begins with materials such as wood, paper, textiles, and other solid objects. These solid fuels provide a substantial source of energy and can release flammable gases when they begin to break down due to heat.

In the early stages of a fire, these solids undergo pyrolysis, which converts solid materials into gases that then ignite and sustain combustion. Thus, while gases and aerosols may play significant roles as the fire develops and spreads, the initial fuel source is predominantly in solid form. This understanding is crucial for fire prevention and firefighting strategies, as it allows responders to anticipate how different materials may react in a fire situation.