What Is The Purpose Of A Deadlatch On A Door Lock?

Whether you are looking at home security or security for a commercial business, you should always be reviewing your current security arrangements and whether you need to improve them. High security levels are very important and you should always be considering the current risk levels of the property you are managing. This is when you might hear terms such as deadbolt and deadlatch and wonder what the difference is.

Essentially, a deadlatch is similar to a deadbolt in that a single bolt protrudes into the door frame to lock the door, but the major difference with a deadlatch is that you don’t need a key to lock it.

What is a deadlatch?

So a deadlatch is a type of door lock that locks automatically when you shut the door, you don’t need to turn the knob or use a key. The latch rests against a metal strike plate mounted on the door frame and uses a bolt to block the door from opening.

The plunger is the most critical part of the locking mechanism with a deadlatch. When you close the door the plunger keeps the lock from retracting when pushed or under pressure. Hence this prevents the door from being opened from the outside, unless you have a key. To unlock the door, pressure is applied to the plunger, ie. by engaging the key, and the plunger retracts the latch and allows you to open the door.

Typically a deadlatch locking mechanism can be set to one of three modes:

• Passage – the latch is open and left permanently unlocked, which allows the door to be opened and closed easily. You might leave a door on this mode if you were moving lots of items in and out of the property, but want to keep the door closed in the meantime.
• Safety – this is the standard mode for using a deadlatch, whereby the door automatically locks when it is closed. A knob on the inside of the door can open and close the lock, so although you need a key to enter from the exterior side of the door, you do not need a key to exit from inside.
• Secure - the interior knob will not function without a key, so the lock is essentially in a deadlocked mode and hence requires a key to both enter and exit.

What is the difference between a deadbolt and a deadlatch?

When you exit through a door with a deadbolt, you need a key to lock the door. However, with a deadlatch, the latch falls into place as soon as you close the door. So you can leave the property without worrying about whether you have locked the door.

What are the advantages of a deadlatch?

The main advantage of using a deadlatch locking system is that you have the convenience of not having to lock the door as you leave a property, if you have the deadlatch in safety mode. This might be helpful if you are leaving with an armful of items and don’t have a spare hand to lock the door. It also means you can’t forget to lock the door, so you have peace of mind that you won’t be sat in a queue of traffic in twenty minutes’ time wondering whether you remembered to lock the door when you left in a rush.

On the flipside, you must always remember to take your keys with you to open the door when you return to the property, unless you have left the deadlatch in passage mode, in which case the door won’t be locked anyway. In safety mode, although you don’t need keys to lock the door, you will need them to unlock it.

It is possible that insurance companies may insist on you installing a certain type of lock, based on the risk and threat levels of the property in question. Deadlatch and deadbolt systems often come into this discussion because of the functionality they offer.