What element limits the mushrooming effect of heat and smoke in large open areas?

• A. Fire Walls
• B. Fire stops
• C. Draft curtains (curtain boards)
• D. Exit access

Answer: (C)

In large open spaces, controlling the mushrooming of heat and smoke relies on creating boundaries that segment the space so the buoyant plume cannot spread unchecked. Draft curtains (curtain boards) act as movable barriers across openings, helping to confine the rising hot gases and smoke to a smaller compartment. By interrupting the vertical and horizontal spread of the plume, they slow the rate at which heat and smoke expand to adjoining areas, reduce the overall heat load, and improve conditions for occupants and firefighters. Fire walls and fire stops provide permanent containment, but in very large open areas they aren’t as flexible or effective for preventing mushrooming as these curtain barriers. Exit access is about the path to egress and doesn’t directly limit heat or smoke spread.