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We’ve spoken a lot about Yale locks so far, especially about auto-deadlocking Yales. Why, if the Yale lock acts as a deadlock, do you need another deadlock underneath? Isn’t that overkill?

No, of course it’s not! Don’t ever be fooled into thinking it is.

A Yale lock, fitted about two thirds of the way up the door, acts as a fulcrum. If you apply enough force to the lower part of the door, you can get enough force against the fulcrum to break the door.

Having a deadlock underneath the nightlatch drastically reduces this fulcrum effect, making it much harder, if not impossible, to break the door without aid from a battering ram or similar.

On top of that, a second lock adds another layer of protection in a simple sense: any intruder would have to get through two locks, not just one, in order to get into your house.

Deadlocks vs sashlocks

There are pretty much just two types of standard deadlock: the deadlock and the sashlock.

A deadlock is a lock that is permanently shut once you’ve locked it, until you unlock it. It doesn’t latch shut, nor does it open without a key (unless there is a thumbturn cylinder on the inside).

A sashlock is all of the above things, plus there’s a latch and a pair of handles. If you pull a sashlock shut, it will latch. However, you can open the door using the handles which are on either side of the door.

In other words, simply latching the door shut provides no security. However, you can lock the sashlock, so that the deadbolt is thrown into the frame. This way, even if you pull the handle, the door will remain locked.

With deadlocks and sashlocks, neither is better than the other. It simply depends on how you use them. An office door might benefit from a sashlock, for example, while a front door which already has a Yale nightlatch on it would work better with a simple deadlock.

bedroom door

Bedroom doors are a typical example of where you might find a sashlock.

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