Can multiple locks be installed on an entryway door?

• A. Yes, with no conditions
• B. Yes - as long as the primary deadbolt lock is functional
• C. No, only a single lock is allowed
• D. Yes, but only on interior doors

Answer: (B)

Exterior entry doors may have more than one locking device, as long as the primary deadbolt is functional. The deadbolt provides the main security function, so keeping it operable ensures the door remains secure. Additional locks can be present, but they should not interfere with the deadbolt’s operation or impede safe egress in an emergency. This is why the best choice is that multiple locks are allowed, provided the primary deadbolt works. The other options aren’t correct because they either imply no conditions, restrict to a single lock, or limit the arrangement to interior doors, which doesn’t apply to entryways.