Nightlatch – What to Know

Nightlatch – What To Know

For my latest blog I thought I’d write about nightlatches or as some people refer to them as a Yale Nightlatch and the different types on the market.

There is some misconception about nightlatches and how they are operated. Hopefully after reading this blog, you will have a better understanding of a nightlatch, how to operate them correctly and which type of night latch will best suit your security needs.

What is a Nightlatch?

A nightlatch is fitted to the surface of the internal side of a door. The lock or rim cylinder sits on the surface of the external side of the door. When the door is in the closed position the bolt or latch sits in a keep which is fixed to the door frame. The bolt has a rounded leading edge which is spring loaded. The bolt is withdrawn into the casing of the nightlatch using the internal lever from inside or using a key from the outside. A snib or button found on the casing of the nightlatch can also be used to hold the latch back. Nightlatches come mainly in two different sizes. This being 60mm backset or for glass paneled doors 40mm backset.

None Deadlocking Nightlatch

None deadlocking Night Latch

A standard nightlatch as seen above, can be deadlocked by using the snib, this is a small button found on the nightlatch. This means the nightlatch can only be deadlocked from the inside which is why they are referred to as “none deadlocking night latch” as they cannot be deadlocked from the outside. Once the snib is operated and the bolt is deadlocked, the bolt cannot be slipped using a card from the outside. It is not good practice to have these as the only form of security on an external door. They should be combined with a British Standard 5 lever Dead Lock.

Key Deadlocking Yale Nightlatch

Keyed N:L

These operate in the same way as the standard nightlatch, except you can deadlock the bolt from outside by using a key in the cylinder. This means that the latch cannot be slipped using the common method known as “card slipping”. Again, these should be used in conjunction with a British Standard 5 lever Dead Lock.

Automatic Deadlocking Nightlatch

yale auto deadlcok

These are different from the two above in the fact that they have a deadlocking pin just above or below the bolt. When the door is closed, the pin is depressed into the casing and in doing so the night latch is automatically deadlocked. Which again will prevent the popular means of entry known as “slipping the latch”. The handle on the internal side can be locked with a key, known as double deadlocking. These are ideal for fitting to a glass paneled doors, as they prevent anyone from reaching through the glass and operating the handle.

British Standard BS:3621 High Security Nightlatches

High security N:L

A British Standard Nightlatch gives the maximum security for a nightlatch and conforms to Insurance approval BS Standard 3621. (Click to read more about British Standards)  They have anti drill features to protect the cylinder against drill attack. These are auto deadlocking when closing the door. They are operated from the inside by using a key and the lever handle. Operation from the outside is by key only. The internal handle can also be locked using a key from the inside. Again double locking the mechanism. In most cases, there is also a snib or button that can be used to hold back the bolt. These nightlatches can only be used on inward opening doors.

When To Use Automatic Deadlocking Nightlatch

Once a nightlatch has been deadlocked or double deadlocked, the bolt cannot be slipped using a card. And so provides a higher level of security. It can also prevent an intruder from smashing a glass panel on the door and reaching through to unlock the door. This also prevents anyone from reaching through the letterbox with tools to turn the internal handle. Why? Because the handle on the inside is locked, ie double locked.  However once the nightlatch has been double locked from the inside the internal handle will not open the door unless the key is used from the inside, therefore occupants could mistakenly be locked inside. Therefore Auto deadlocking nightlatches as a general rule should not be used on shared or communal doors.

There are nightlatches on the market that still meet BS: 3621 for high security but the internal handle cannot be locked, therefore anyone inside can operate the internal handle to open the door. These are used were a high level of security is required on communal or shared property’s. This is known as “Egress Function”.

These can also be fitted with an electric keep, known as an electric door release. Though they can be tricky, may be worthwhile hiring a Hove locksmith.

Keyless Egress High Security Nightlatch


I hope by reading this blog you will have a better understanding of night latches and there use. If you require any further information, a Shoreham Locksmith or advice on your home security please contact Jeff at Seymour Locksmiths on 07710 408414.

About Jeff Seymour

I am a professional locksmith based in West Sussex, UK. I am fully trained and accredited by the UK Locksmith Association as well as independent bodies such as Checkatrade. In 2014 I founded my locksmith company called Seymour Locksmiths. My passion for all things locks and locksmithing continues to this day as I continue to grow Seymour Locksmiths and share my knowledge with the world through my blog.
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