Manual, key-operated locks are the most common type of security device used to control access through doors. While many companies have installed sophisticated electronic access control systems, the manual lock is still used on most doors. In addition, many doors that are controlled by an electronic access control system still have a manual lock on them that allows override using a key.

Most manual locks that are in use today are using technology that was developed more than eighty years ago. While this technology has proven reliable, standard manual locks have many weaknesses. Some of these weaknesses include:

• Keys to standard locks can be duplicated: Most standard locks use keys that can be easily duplicated by any locksmith or key shop. Stamping “Do Not Duplicate” on the key offers little protection; many key shops will duplicate the key despite the warning. Once the owner has given out a standard key, he can never be sure just how many copies of the key might have been made.
• Standard locks can be “picked” open: Most standard lock cylinders can be opened using lock picks or a device known as a “pick gun”. While some standard locks require a level of skill to pick, many locks can be opened easily by the novice. Inexpensive locks and locks that have been master-keyed are often easiest to pick.
• Standard locks can be “drilled” open: Most standard lock cylinders can be easily drilled open. This has become an increased problem since the introduction of cordless drills.

To solve many of the weaknesses of standard locks, “high-security” locks have been developed. There are many different brands and styles of high-security locks, but most offer the following benefits:

• Patented or Restricted Keys: Most high-security locks use keys that are patented or otherwise restricted. Distribution of key blanks is strictly limited, and special equipment is required to duplicate keys. Duplicate keys are generally only available through qualified locksmiths or the factory, and only upon written authorization of the facility owner or his designated representatives. Because it is extremely difficult for an unauthorized person to obtain a duplicate key, the facility owner can be fairly confident of the number of keys to his facility that are in circulation.
• Virtually “Pickproof”: Most high-security locks use special mechanisms that make them extremely difficult, if not impossible, to “pick” open. While there are a handful of champion locksmiths in the world who might be able to pick open a high-security lock if given enough time, picking a lock of this type is generally beyond the capabilities of even the most seasoned of criminals.
• Drill Resistant: Most high-security locks are designed to resist attacks by drilling. Protective measures can include the use of a hardened metal case, special hardened metal pins or disks placed in the path where the drill must penetrate, and special metal shields to prevent attack on the lock itself. While most high-security locks can be drilled open, this is a time consuming and difficult task.

Silva Consultants strongly recommends the use of high-security locks, particularly on the exterior doors of your facility. High-security locks are also a good choice for use on doors that lead into areas that contain sensitive information or high-value assets

For safety reasons, building and fire codes require a specific number of exit doors out of every occupied portion of the building. In most cases, at least two exits out of each room is required. Many times, doors are installed specifically as “emergency exits”, and are used for no other purpose. Exit doors must allow exit at all times and therefore must be kept unlocked in the direction of exit.

Unfortunately, exit doors can often create a security weakness. This is especially true when they are located in out of the way places that are unattended by employees or security personnel. For example, in a retail store, emergency exit doors are often located in the rear of the store, far away from the front check-out area. A thief can grab merchandise, and then quickly run out one of the exit doors. A similar type of vulnerability exists in many other types of commercial and institutional settings, where items of value can be taken out of the building through an emergency exit door.

To combat this problem, emergency exit doors are often equipped with “exit alarms”. Exit alarms are installed on the emergency exit door, and will cause an audible alarm to sound when the exit door is opened.

Exit alarms do a good job of discouraging misuse of the emergency exit doors by employees and the general public, but don’t always stop a more aggressive thief. This is because the thief knows that it will take time for an employee or a security person to respond to the door when the alarm sounds. This gives the thief ample time to grab the merchandise, and then quickly run out the door. The alarm sounds, but by the time an employee responds to the door, the thief is long gone.

In recognition of this problem, many building codes have been modified to allow the use of “delayed-egress locking systems” on emergency exit doors. The delayed egress locking system typically consists of an exit push bar, an auxiliary locking device, an audible alarm, and a special electronic control package. The delayed-egress locking system operates as follows:

1. When a person approaches the door to exit, they press on the exit push bar. This causes the audible alarm to immediately sound, but does not unlock the door.
2. The alarm continues to sound for a preset period (usually 15 seconds).
3. At the end of the preset period, the door unlocks, allowing free exit.

The advantage of the delayed-egress locking system is that it provides a delay between the time that a person activates the alarm and when the door actually unlocks. This delay gives additional time for an employee or security person to respond to the door once the alarm has been activated. The delayed-egress locking system serves as a strong deterrent to the “grab and run” thief who doesn’t want to wait 15 seconds or more to make his exit from the premises.

Most building and fire officials will approve the installation of a delayed-egress locking system provided that the following requirements are met:

• The building must be equipped with an approved automatic fire detection system or approved automatic fire sprinkler system.
• The delayed-egress locking system must automatically unlock the doors upon activation of either the fire detection system or sprinkler system.
• The delayed-egress locking system must automatically unlock upon failure of power to the locking system.
• Upon activation of the exit push bar for a period of not more than 3 seconds, the system shall begin an irreversible process that releases the locking mechanism within 15 seconds (up to 30 seconds if approved by the authority having jurisdiction). The system shall sound an audible alarm at the door when the exit push bar has been pressed to provide assurance to those attempting to exit that the system is functional. Once the locking mechanism has been released, it shall remain unlocked until the system has been manually reset.
• Appropriate signage must be provided at the door that reads: “PUSH UNTIL ALARM SOUNDS – DOOR CAN BE OPENED IN 15 SECONDS”. Lettering on sign shall be at least 1″ high.
• Emergency lighting shall be provided at the door.
• All components of the delayed-egress locking system shall be UL listed.

There are three basic types of delayed-egress locking systems.

The first type of delayed-egress system uses an electromagnetic lock in conjunction with either a standard mechanical push bar or an electronic “touch sense” bar. These types of systems generally require an external control panel.

The second type of delayed-egress system uses an electromagnetic lock that contains a built-in control system and a built-in “exit sensor”. The exit sensor detects when the door is pushed open and eliminates the need for any special type of exit push bar. This makes it ideal for retrofit installations on existing exit doors.

The third type of delayed-egress system uses a special type of mechanical exit device. All components of this system are contained within the exit device itself. This type of system minimizes the number of components required at the door and is best suited for new construction applications.

Here are a few things to consider before installing a delayed-egress locking system:

• Be sure to obtain approval from the “authority having jurisdiction” (AHJ) before installing a delayed-egress system.
• Most AHJ’s will not approve delayed-egress systems on exit doors for Group A (Assembly) occupancies. These occupancies typically include exhibition halls, auditoriums, gymnasiums, restaurants, nightclubs, libraries, museums, theaters and other such buildings where 50 or more persons may gather. It is especially important to obtain approval from the AHJ when contemplating the installation of a delayed-egress system in any such facility.
• If the exit door is both an emergency exit door and a fire separation door, the hardware used on the door must provide positive latching of the door, even when it is unlocked. This normally requires the use of a fire-rated mechanical exit device on the door.
• It is generally not acceptable to have more than one delayed-egress device along the path of travel to an exit. For example, if you had a delayed-egress device on a second floor door to a stairwell, it would not be acceptable to have another delayed-egress device on first floor door that exits this stairwell to the outside. 

Many delayed-egress systems offer a “nuisance” alarm feature. This feature minimizes false alarms by sounding a short audible tone whenever a person first presses on the door. If the person stops pressing on the door within one second, the tone stops, and the delay sequence is not initiated. If the person presses on the door for longer than one second, then the exit alarm sounds and the 15 second countdown begins.

Some delayed-egress systems now offer a voice announcement feature. This feature gives warning messages in a human voice and can provide a verbal countdown of the time remaining until the door unlocks.

Electric strikes are one of the most common types of lock hardware used with card access control systems.

Frequently, electric strikes are used with “cylindrical locks”, sometimes called “knob locks”. These locks are similar to the type that most people have on their doors at home. One common problem that occurs when cylindrical locks are used with electric strikes is that the “deadlatch” fails to work properly.

The “deadlatch” is a small metal piece that is located at the back of the latch assembly. The purpose of the deadlatch is to prevent the latch from being pushed back with a knife or credit card when the door is closed. When cylindrical locks are used with on doors without electric strikes, the deadlatch rests on the metal strike plate that is mounted on the door frame. The latch itself goes into the hole on the strike plate, but the deadlatch rests on the edge of the hole and is depressed against the strike plate when the door is closed. When the deadlatch is depressed, the latch cannot be pushed back from the outside.

When an electric strike is installed on a door, the electric strike takes the place of the regular strike plate. Electric strikes have a much larger opening or “cavity” than a regular strike plate does. The larger cavity allows the electric strike to work with a variety of different type of locksets and provides a little “wiggle room” to allow the electric strike to operate properly.

When a cylindrical lock is used with an electric strike, the latch enters into the cavity when the door is closed. But what about the deadlatch?

The electric strike is designed so that the deadlatch will rest upon the “lip” or “keeper” that is at the front of the electric strike. Unfortunately, the keeper of the electric strike is usually only about an 1/8″ wide. This makes the alignment of the electric strike in relationship to the deadlatch very critical. If the electric strike is not perfectly aligned, the deadlatch will fall into the cavity rather than resting upon the keeper as it is supposed to. This prevents the deadlatch from operating correctly, and allows the latch to be easily pushed back using a knife or credit card. The result: a door that can be very easily opened by an intruder.

When Silva Consultants conducts a security assessment, we find that the deadlatch fails to work properly on as many as 6 out of 10 doors that we examine!

Most electric strike manufacturers recognize that the deadlatching function will not work properly when their electric strikes are used with cylindrical locks. Many manufacturers specifically state in their literature that proper operation of the deadlatch cannot be guaranteed.

In most cases, card readers and electric strikes are used on doors that allow access into high security areas. It is ironic that, in most cases, doors equipped with cylindrical locks and electric strikes are easier to force open than doors with regular manual locks.

What can the security system user do to correct this weakness? Here are a few suggestions:

• Examine all doors that have cylindrical locks and electric strikes to determine if the deadlatching function is working properly. Look to see if the deadlatch rests upon the keeper as it is supposed to. If the deadlatch goes into the strike cavity instead of resting on the keeper, the deadlatching function isn’t working properly.
• If the deadlatch appears to be resting on the keeper, give the door a good hard push and pull. In many cases, this will cause the deadlatch to come off of the keeper and fall into the strike cavity. If this happens, the deadlatch can be easily defeated by an intruder.
• If the deadlatching function isn’t working properly, or can be easily defeated by pushing or pulling on the door, the first thing to do is to call in a qualified electric hardware installer to examine the door. In many cases, the electric strike or door can be adjusted so that the deadlatch operate correctly.
• On outswinging doors, consider the installation of a “latchguard”. The latchguard is a metal plate that installs on the outside of the door and protects the latch from tampering. Latchguards cost less than $50 and can be installed by a qualified locksmith.
• For high security doors, consider replacing the cylindrical lock with a mortise lock. The deadlatch provided on a mortise lock rests either above or below the electric strike cavity when the door is closed. A mortise lock, when used with a properly installed electric strike, is immune to the deadlatching problem and provides much better security than a cylindrical lock.
• For very high security doors, consider using an electric mortise lock instead of an electric strike. Electric mortise locks provide excellent security, and in our opinion, are the best choice for use on high security doors. When building a new facility, or planning an new card access system, consider the use of electric mortise locks wherever possible. The cost of installing electric mortise locks is only slightly higher than the cost of installing electric strikes when the hardware is provided as part of a new construction project.