Which construction type may contain a high concentration of wood that can contribute to a fire's intensity once ignition occurs?

• A. Type I
• B. Type IV
• C. Type V
• D. Type X

Answer: (B)

When evaluating fire behavior across building types, the amount of wood present in the structure acts as a major fuel source that can drive fire intensity once ignition occurs. Heavy timber construction uses large wood members for the structural framework, along with substantial wood in interior elements. That means there is a high concentration of wood inside the building, which can continue to feed the fire and amplify heat release if a flame starts there. The mass of these timber members also influences how the fire develops and how long it takes for structural elements to fail, which affects suppression and rescue tactics. In contrast, noncombustible or fire-resistive types have little to no wood in critical structural components, and other types may include wood but not to the same extent as heavy timber. So, the presence of substantial wood in heavy timber construction makes it the type most associated with a potential high wood fuel load that can intensify a fire once it starts.