We began this four part series briefly reviewing the 4 basic functions of door hardware:

  1. To hang the door
  2. To secure the door
  3. To control the door
  4. To protect the door

We previously covered the first function that needs to be taken care of before anything else which is to hang the door. In this article we will cover the next step which is to secure the door.

Secure the door

Once the doors are swinging in the opening with some type of hinges, the next thing you need to do is to make sure the door will stay closed when it should be kept closed. There are a number of ways to secure a door. Keep in mind that codes and functionality will often determine what types of locks need to be used.

There are three main types of commercial door locks that you are going to see used to secure a door.

  1. Cylindrical Locks
  2. Mortise Locks
  3. Exit Devices

Cylindrical Locks

In commercial buildings, cylindrical locks are used for anything from front entrances to basement storage rooms. They require a circular lock prep in the door and usually require a standard ANSI 4-7/8″ (ASA) strike prep on the frame. Depending on the grade of the lock specified, there will be a wide array of functions available to secure the door.

Cylindrical Door Lock

Cylindrical Lock

Mortise Locks

Mortise locks can be much more complex than cylindrical locks but for a couple of good reasons. The first reason is that the lock body of a mortise lock allows for many locking function combinations. The ability to add a deadbolt into the same lock as the latching hardware is a huge benefit.

Mortise Lock

Mortise Lock

Mortise locks come in even more design styles than cylindrical locks do. The option to have an escutcheon plate or rose lever allows an architect to create a unique design.

One word of caution for mortise locks: pay attention to the handing of the door. The cylinder prep for a mortise lock requires a hole to be cut into the face of the door and the way the door is handed will determine where that hole is cut in.

Exit Devices

The final type of lock to secure the door that we will mention here is the exit device. Exit devices come in many shapes and sizes but share a common push bar feature. Exit devices will also be labeled as either “panic hardware” or “fire rated hardware”. An exit device allows a door to be locked securely from the outside while allowing occupants inside to immediately egress (exit) without any special knowledge or use of a key.

Door Exit Devices

Exit Devices


Securing a door is important to the safety and protection of the people and assets inside of a building or space. Whichever locking method is specified to secure the doors on a project there are many combinations of functions and designs to accomplish that security and each has its benefits.