What is a Mortise Door Lockset?

yale mortise door lockset

Have you heard the term “mortise door lockset” before? You probably have heard of it but if not it is understandable – a residential home usually does not have any mortise lock sets. Mortise locksets are typically used in North America is a commercial setting, such as offices or hospitals. Generally, mortise locks are heavy duty and more secure than a standard residential lock. What is a mortise door lockset and do you need one in your home?

Mortise locks were used before the invention of the cylindrical lock. They have been around since the early 1700’s. In the United States you would only see them in upper class homes and even then not all of their doors had these types of locks. They would only be used on rooms where more security was needed. And because cylindrical locks have not caught on in Europe as they have in North America, you can still see a lot of the mortise door locksets in that part of the world.

Most likely, you do not need one in your home. Mortise locks provide many different uses that are not needed in your average home. They come in models that are as basic as a passage lever like you would use on a hall closet to an electronic multipoint lock that locks the door at the top, bottom and jamb strike.

As you can see in the above pictures, mortise door locksets fit within a “pocket” or mortise in the door. Cylindrical locks, typical hardware in most homes, need a single bore.

Differences in Mortise Locks and Cylindrical Locks

There are many differences between Schlage mortise locks as opposed to a cylindrical lock:

  • Come standard as Grade 1 lock
  • Always UL fire rated up to 3 hours
  • Can be used with many different lever styles
  • Many different uses with the same lock body – passage, deadbolt, privacy indicator, electronic access, etc.
  • Mortise locks typically cost more than 5 times the cost of a cylindrical lock
  • They are more secure than a cylindrical lock and are made to be used many times more than a cylindrical lock

Can You Use a Mortise Door Lockset?

mortise door lockset
Mortise Lock Body without handle or thumbturn

Sure. There are a few thing to keep in mind when deciding if you want a mortise lock.

  • The door you are putting it in must be at least 1.75 inches thick. This is because the whole lock body fits within the door
  • You will have to order the door “prepped” – cut or notched – or cut the pocket yourself to fit the whole lock body within the door
  • Many times the levers that can be used on mortise locks are not as decorative as levers on typical residential locks, your choices of levers might be limited
  • The backset – distance from center of lock to edge of door – is set and cannot be adjusted

Increased Security with a Mortise Lock

When installing a mortise lock it requires a chunk of the door to be removed. This weakens the door at this point, however, once the mortise lock is installed it will increase the security of the door. This is because you have installed a solid metal body that is roughly 4″x6″ with the latch and deadbolt in the same lock. It is easier to attack a single point on a door like a deadbolt than it is to get around 5″ of deadbolt, latch and auxiliary latch. However, the strike will still need to be installed with 3″ screws to get to the king stud.

Locking it up….on Mortise Door Lockets

Mortise locks are very versatile and can made to be used for many different functions, many more than a typical house would need. The lock cylinders can be interchangeable and can be used with many different types and styles of levers and knobs. Because of this, these locks are very useful in commercial buildings like offices, hospitals, hotels and schools. All places where they would be subjected to abuse and used many times throughout the day. Next time you’re in an office building or a hospital take a look, I’m sure you will see one.

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