How to find the right door latch: A Step-by-Step Guide


 From mortise locks to screw-on locks: When choosing, you must pay attention to the dimensions of the bolt, strike plate, latch case, lock cylinder and locking mechanism. Whether DIN left or DIN right, the opening direction of the door must also be taken into account. Here you can find out everything you need to know about mortise latches, security locks and more!

How to find the right door latch

Choosing a door latch: important criteria

This makes replacing your door latch child's play:

  • Remove the old model.
  • Take a tape measure, a piece of paper and a pencil. Measure everything and write down the measurements.
  • Pay attention to the opening direction of the door, compare the locks and choose the right one!

Replacing the door latch: You need to pay attention to these features

If you are not an expert, you can determine the features that your new door lock must have based on the following criteria:
  • Mortise lock or screw-on lock;
  • vertical or horizontal;
  • DIN right or DIN left;
  • Dimensions of the lock case, the faceplate, the bolts, the lock nut and the distances.

Locking mechanism

Locking can be achieved using various mechanisms:

  • Locking cylinder: Locking via a cylinder that is operated with a key.
  • Beard lock: Locking via an integrated mechanism in the lock case with a bearded key.

The right lock cylinder

door latch cylinder

Locking cylinders are usually the same size

The security level depends on the model: protection against mechanical break-in attempts, drilling protection, security card, etc. Look for the VdS quality seal. Locking cylinders are available in different versions:

  • A locking cylinder with emergency and danger functions can be opened from the outside if a key is inserted from the inside;
  • Half cylinder, can only be closed from one side,
  • The knob cylinder is operated with a key on one side and a knob on the other.
You can find out more about the meaning of all these terms in the next section!

Technical terms for door latch: a small locksmith lexicon

To understand how a door lock works, it is important to know the correct terms for its individual elements and functions.

Door lock: definitions

  • Door lock: Locking system that can be operated with a door handle, key or knob. Door locks are used to close and lock doors - door handle + key.
  • Closing: A door is closed with a handle, which in turn operates a lock.
  • Locking: Not to be confused with closing a door. Doors can be locked using key-operated locks.
  • Locking cylinder: It is also known as a profile cylinder. It has a cylinder core with a cylindrical shape and represents the security element of the lock.
  • Deadbolt lock: Lock with manual locking from the inside using a knob and from the outside using a key.
  • Lock case: External part of a lock that contains the entire locking mechanism. It can be mounted or installed.
  • Latch or latch: solid, movable part that locks a door when locked in the strike plate. Latches and deadbolts are the parts of the lock that are moved in and out using keys or door handles. Some traps can be reversed and are therefore suitable for left and right opening doors.
  • Locking lug (locking cam): Latch of the cylinder that enables locking.
  • Lock nut: a rectangular, cuboid piece of metal that connects the handles to each other, is guided through the lock and activates the latch and bolt. It is available in different sizes. 8 mm is common for room doors and 10 mm for front doors.
  • Door handle: often in the shape of a latch, allows the latch to be released from the striking plate and thus opens the door.
  • Strike plate: Metal element on the door frame, forms the housing into which the latch and bolt slide for closing or locking.
  • Pull handle: replaces a handle on the inside of a lock. Handle that you pull to release the latch from the strike plate.
  • Forend: an attached part in a mortise lock that allows the lock case or striking plate to be attached. Its ends can be round or square.

Determine the opening direction of a door

Door opening to the right

Your door opens to the right (DIN-right) if you stand in front of the hinge side and the hinges are on the right.

The door opening to the left

Your door opens to the left (DIN left) if you stand in front of the hinge side and the hinges are on the left.

To tell whether a door is DIN right or DIN left, remember the following sentence: “DIN is where the hinges are visible”.

 Door Latch Types: Overview

For the sake of simplicity, we differentiate between two types of locks:
  • Mortise locks or built-in locks;
  • Screw-on locks.

Mortise lock: detailed view and function

A mortise lock sits in the door leaf. This must therefore be wide enough to accommodate the lock case of the door lock. Latches and latches enable a door to be closed and locked. The latch is usually reversible so that it can be used in both opening directions.

Screw-on lock: detailed view and function

A screw-on lock is attached to the door leaf instead of in the door leaf. It is suitable for thin doors, metal doors and for anyone who does not want to chisel out their wooden doors. These screw-on locks allow for closing and locking. Here too the trap can be reversible.

Select mortise lock

Take measurements for a mortise lock

Since the lock is located in the door, you have to pay close attention to the dimensions when making your selection. When replacing such a lock, you must consider the following points:
  • Height and depth of the lock case;
  • Distance between the lock nut and lock (cylinder lock or warded lock);
  • Dimensions of the latch and deadbolt so that they fit into the strike plate;
  • distance between latch and latch;
  • Distance between the faceplate and lock nut/lock cylinder.
  • Dimensions and shape of the cuff end (width and height, square or round).
In short, your new mortise lock must have the same properties as the old lock if you do not want to carry out any modifications to your door. If the lock nut is smaller, you will need a reducer to operate a 6mm lock nut with a 7mm square pin.

How to find the right screw-on lock

Take measurements for a screw-on lock

Its design makes choosing a screw-on lock easier. To ensure that the exchange goes smoothly, you should pay attention to the following:
  • Diameter of the cylinder for cylinder locks;
  • size of the lock box (for painted doors, a large box is better than a small one);
  • Distance between lock nut and lock (cylinder lock or warded lock with matching key);
  • Size and shape of the cuff (width and height, square or round).
  • Distance between the faceplate and lock nut/lock cylinder.
  • Height and depth of the lock case.
  • The size of the latch and deadbolt does not matter as the striking plate is mounted face-to-face (delivered with the lock).

Difference between single and multiple locking

The difference between these two systems lies in the number of locking points, i.e. the number of latches.

  • A single lock can be built into the door or attached to the door. It only has one latch, i.e. one point to lock the door.
  • A multi-point lock can also be screwed onto the door or inserted into the door. It has several locks: The door is locked with several bolts. Most multi-point locks have three to four latches. This type of locking is usually supplemented with an espagnolette lock on the top of the door.

Espagnolette locks under the microscope

An espagnolette lock consists of one

Cylinder latch and warded latch: differences

Door latches have different locking mechanisms.

Cylinder lock

To buy a new lock, you need to know its shape, length, security level and number of keyholes. The key is usually flat and has one or two profiles with cuts or punches.

Buntbeard Castle

The lock is integrated into this lock. The key is usually quite heavy. It is called a Buntbeard key or, if it has millings, a Chubb key. This type of lock is suitable for indoor use.

These locks can be constructed horizontally or vertically, depending on the format of the lock case. If they are taller than they are wide, they are said to be vertical. If they are wider than they are tall, they are said to be horizontal.

There are also electric locks. These are door locks that can be opened with a card, badge or via a key code (from the inside). Some locks can even be opened remotely.
Certificates and standards

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