A bathroom in a dwelling unit must be provided with a minimum intermittent exhaust of how many CFM?

• A. 25 CFM
• B. 50 CFM
• C. 75 CFM
• D. 100 CFM

Answer: (B)

Ventilation in a bathroom is needed to remove moisture and odors quickly when the space is in use. The minimum intermittent exhaust rate of 50 CFM provides enough air change during typical bathroom use to pull out humidity and prevent mold and moisture damage. A lower rate, like 25 CFM, would be insufficient for effective moisture removal in most bathrooms, while higher rates such as 75 or 100 CFM are better suited for larger bathrooms or areas needing more aggressive ventilation. Since the question specifies intermittent operation, 50 CFM is the standard minimum that meets common residential code expectations.