One method to keep a stairwell free of smoke is to pressurize the stairwell.

• A. False
• B. True
• C. Not applicable
• D. Depends on system

Answer: (B)

Smoke-control through stairwell pressurization relies on maintaining higher pressure in the stairwell than in surrounding spaces so smoke can’t easily enter. By supplying dedicated air to the stairwell with its own controls, the stairwell becomes a higher-pressure zone. Smoke naturally moves from higher pressure to lower pressure, so doors stay more effectively closed to smoke and any smoke that tries to infiltrate is pushed outward. This creates a tenable path of egress for occupants and a safer space for firefighters, provided the system is properly designed, installed, and coordinated with the building’s other smoke-control measures. So, pressurizing the stairwell is a valid method to keep it free of smoke.