The minimum intermittent exhaust for a residential bathroom is 50 CFM. True or false?

• A. True
• B. False
• C. Not specified
• D. Only for fans over 8 ft ceilings

Answer: (A)

Ventilation in a bathroom is needed to remove humidity and odors and prevent mold, so codes specify a minimum exhaust rate when the fan runs intermittently. For a typical residential bathroom, that minimum is 50 cubic feet per minute. This figure ensures enough air is moved to effectively vent moisture during use. Some codes allow a lower rate if the fan runs continuously, but for intermittent operation the standard value used in exams is 50 CFM. Therefore, the statement is true. The other options don’t fit because they imply different, nonstandard conditions (not specified, or dependent on ceiling height) that aren’t the typical requirement.