What is a night latch?
A nightlatch is rim lock that is mounted to the inside surface of the door. It features a latch that is withdrawn by a handle on the inside and by key from the outside. They also usually feature a snib that allows the latch to be either held back in the unlocked position or to be deadlocked when the door is closed. The latch is accepted on the frame side by a keep or strike.
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Anti Thrust Bolt
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|3 ||Keep/Strike |
|4 ||Handle |
|5 ||Snib |
Fig1.1 Anatomy of a Nightlatch
What sizes do they come in?
The case sizes of nightlatches vary considerably across the brands but the backset remains fairly consistent. The standard backsets are 40mm and 60mm, although, some Union locks are available in a 50mm backset but they're rare.
40mm Backset nightlatches are generally used on doors with limited space e.g doors with glass panels or narrowboat doors and are known as narrow stile nightlatches.
60mm Backset nightlatches are what most people have on their front door and are known as standard stile nightlatches.
What types are there?
There are several different types on night latch and they all have their own capabilities and attributes.
British Standard Nightlatches
These nightlatches conform to BS3621 and bear the British Standard Kitemark. They are designed for use on external doors and offer the highest security in a nightlatch. There are two types of BS nightlatch: Key Egress and Keyless Egress. Key Egress night latches feature a lockable internal handle that offers additional security against slipping and also makes them ideal for use on doors with glass panels as the nightlatch cannot be opened even if the glass panes are smashed. They are not suitable for communal entry doors, though, as the locked handle will create problems with ease of exit in the case of an emergency. Keyless Egress night latches offer the same security against slipping and bumping as Key Egress locks but they do not feature the lockable handle. This makes them the ideal choice for communal entry doors but not suitable for glass panelled doors.
Standard Nightlatches (Also known as Non-Deadlocking Nightlatches)
Non-deadlocking nightlatches are your basic nightlatch and are the locks you see being opened with a credit card in the movies (slipping). They should never be used on an external door unless there is also a British Standard 5-Lever Mortice Deadlock fitted. They are suitable for use on the internal door of dual entry properties provided the external door has sufficient security but remember to lock the deadlock at night. They feature a latch which is withdrawn by a lever handle from the inside and a key from the outside. The latch cannot be deadlocked from the outside but engaging the snib allows most standard nightlatches to be deadlocked from the inside.
A deadlocking nightlatch has the same functionality as a standard nightlatch except that you can deadlock the latch from the outside by key. This offers better protection against slipping and also prevents the latch being withdrawn by gaining access to it through the letterbox. Some deadlocking nightlatches also feature a key lockable internal handle.
Auto Deadlocking Nightlatches
Auto deadlocking nightlatches feature an additional pin situated below of above the latch which is pressed into the mechanism when the door is closed and deadlocks the latch. This offers protection against slipping. Most of them also allow you to deadlock the internal handle by key.
Designed in the classic original Yale style, these locks offer the same functionality as standard nightlatches.
Deadbolt Nightlatches feature a deadbolt instead of a latch. The deadbolt is automatically thrown when the door is closed.
These nightlatches have a spring loaded roller catch instead of a latch. This means that the door can be opened from the inside or the outside by pushing or pulling. The rollerbolt can be withdrawn or deadlocked from the inside by handle or the outside by key.
Drawback locks are nightlatches which feature a latch and a deadbolt. The latch is withdrawn by key from the outside and handle from the inside. The deadbolt is withdrawn by key from both sides.