When is it typically inappropriate to ventilate from the roof?

• A. When the roof is structurally unstable, fire involvement is too close to the roof line, or gas/fuel hazards exist that could ignite with ventilation.
• B. When the roof is structurally unstable.
• C. When it is raining heavily.
• D. When the building is unoccupied.

Answer: (A)

Ventilation from the roof is risky when the fire environment could be worsened by opening up that level. If the roof is structurally unstable, opening it can trigger a collapse or fail the roof, endangering crews and trapping people. If the fire is already burning near the roof line, venting can feed the flames, push heat and gases along the roof surface, and compromise its integrity or drive the fire into upper areas. Gas or fuel hazards present near the roof can be ignited or cause an explosion when air is introduced through roof openings. In short, roof ventilation becomes inappropriate when the roof could fail, when the fire is close enough to the roof to be driven or intensified, or when flammable vapors could ignite due to the ventilation.