Which of the following statements about exterior locking of exit doors is correct?

• A. Key locks are permitted on the outside of exit doors in all occupancies
• B. There must always be a key available to exit doors from inside
• C. It is acceptable to lock exterior exit doors with a key from the outside during daytime only
• D. Key locks on the outside of exit doors are not permitted

Answer: (D)

Exterior key locks on doors that serve as exits are not allowed because exits must be readily openable from the inside at all times to ensure immediate egress in an emergency. A lock on the outside can trap occupants inside, especially during a fire when quick escape is critical and keys may not be available or visible. Instead, exits use panic hardware or other approved quick-release devices that unlatch with simple pressure from inside. In some cases, approved access-control systems are allowed, but they must release for egress under specified conditions and never rely on a key on the outside. This is why the statement about exterior key locks being not permitted is the correct understanding.