Most manufacturers make a range that includes both deadlocking and non-deadlocking nightlatches but what is the difference and when should you use them?
What's the Difference?
Deadlocking nightlatches such as the Yale 85 or 89
Series can be locked from the outside of the door by the key.
The handle on the inside will be locked and will not retract the latch. This is sometimes known as "Double Locking". Non-deadlocking nightlatches (such as the Yale 84 or 88 Series) by contrast cannot be double locked.
When to use a deadlocking nightlatch?
Once a nightlatch has been deadlocked the latch cannot be slipped with mica card so it provides a higher level of security. It can also prevent an intruder from smashing a glass door panel to reach in and unlatch the door.
However, once the nightlatch has been deadlocked from the outside, the internal handle will not open the door. Therefore occupants could be locked inside and deadlocking nightlatches should not be used in shared or communal houses as a rule.