Latch Protection and Security Strikes

Feb. 1, 2010
Latch protection products limit access to the latch and the bolt areas between the lock edge of the door and the jamb.

An installation is only complete when the appropriate security hardware has been installed. The job is not completed with just the installation of a high security mechanical or electro-mechanical latch or deadbolt lock. We must take into account the traffic, location, materials and construction of the opening, plus the interaction between the door and the jamb to determine the correct hardware.

Is the door being serviced susceptible to vandalism or forced entry attacks? By code, most exterior commercial doors are required to open out. This places the latching mechanism in view from the non-secured side. To make matters worse, many doors are either installed incorrectly or have changed because of settling, time or natural affects. The security of the opening decreases when the gap between the lock edge of the door and the jamb exceeds 1/8”.

If there is a wide gap and the strike plate has not been properly mounted, the door can possibly be opened by manipulating or cutting the latch or bolt. On center hung doors, the deadbolt can often be cut, as there usually is no protection to prevent sawing.

For most wood and hollow metal doors, a jamb stop deters sawing of the deadbolt. However, if the gap is wide enough, a battery operated rotary grinder can be used to gain entry.

On doors that are equipped with latch mechanisms, the latches can be slid back using different methods. My favorite easy entry is to “loid” open the door, a method that was introduced more than 50 years ago. Loiding uses a thin piece of plastic or film to slide between the tip of the latch and the strike in order to be able to open the door. This method will work on spring latches and dead latches where the dead latch extends into the opening of the strike plate. The term loid comes from the word celluloid (film), where a piece of 35mm movie film could be used to open a locked door.

To protect against loiding and other forms of attacking the latch or bolt, a variety of products have been introduced over the years using many different names. These latch protection products limit access to the latch and the bolt areas between the lock edge of the door and the jamb. Some of these include the names guard plates, latch guards, astragals, vandal guards, latch protectors, anti-vandal handles, etc.

In many instances, these terms are interchangeable. However, the basic design is to obstruct the lock edge of the door, covering the exposed portion of the latch or bolt. In addition to protecting the latch or bolt, these devices can also provide some protection for the exposed portion of the rim or mortise cylinder. As example, Major Manufacturing sells an aluminum door guard plate that provides protection for the latching mechanism and the lock cylinder.

For some exterior doors, such as electric room doors or vandal prone areas, there are latch protectors with lock cylinder wrenching protection that have built-in handles. These handles eliminate the need for exterior trim. Trimco manufactures Anti-Vandal Handles in a number of configurations.

For our purposes, this article will use a description “Latch Protection” instead of a specific product name. Latch protection is available in different sizes and shapes to accommodate different door and jamb configurations and composition as well as different strike plate types and locations. Latch protection is available in varying thicknesses and different materials. For example, Don-Jo offers stainless steel latch protection plates for out-swinging doors.

The construction and swing of the door, its location within the jamb and the type of lock, strike plate or electric strike and finish determines the latch protection. Latch-Gard products are available in several different finishes to match the lock hardware.

For example, if an out-swinging wood or hollow metal door located along the forward edge of the jamb (flush) is equipped with a latch bolt function mortise lock. The lip of the strike plate extends beyond the jamb.

The latch protection must have a plate tall enough to permit the mounting screws to be located above and below the mortise body. The plate must be narrow enough to mount onto the exterior of the door and not obstruct the trim. If no trim is desired, an anti-vandal handle can be installed.

The plate must have a raised area (bump-out) to accommodate the exposed lip of a strike plate on a flush door equipped with a mortise or cylindrical lock strike plate. No bump-out is required for deadbolt protection.

If the door is equipped with a cylindrical lock instead of a mortise lock, different latch protection will need to be installed to accommodate different backsets and trim dimensions.

There is latch protection designed for offset doors as well as flush doors. If the door is just about flush with the forward edge of the jamb, the latch protection is a flat or relatively flat plate. If the door is offset, having a reveal, the latch protection must have a compatible series of bends for the door to close and latch.

In addition, some latch protection is equipped with one or two welded pins that enter drilled holes in the jamb. The purpose of the pin is to prevent an aluminum or metal doorjamb from being spread to create an opening large enough to accommodate the extended bolt, allowing the door to swing open.

Latch protection is also available for in-swing doors. The latch protection can consist of two “U” shaped pieces of metal. One piece is mounted onto the face of the jamb stop with the “U” shape pointing towards the door. The second piece is mounted onto the door. When the door closes, the two pieces interconnect stopping access to the latch or bolt area and preventing access to the latch protection mounting screws. M.A.G. Engineering Inc. manufactures this type of interlocking latch protection.

Out-swing latch protection is usually mounted onto the door using carriage bolts or heavy duty rivets. Depending upon the manufacturer, the carriage bolts or rivets may or may not be supplied.

A less visible alternative to surface mounted latch or bolt protection is the security strike. Oversized strike plates are available in a variety of metals, sizes and applications. They are designed to minimize the gap between the lock edge of the door and the jamb and to provide an increased level of security against forcing open a door.

These “super sized” strikes are normally installed on in swinging doors. Security strikes are available for latch and deadbolt locks as well as combination of latch and deadbolt openings. They are available in different lengths, some more than 18 inches and have upwards of nine mounting screw holes. Most of these strikes are designed to accommodate #10 screws three inches or longer. The screws are designed to not only screw into the jamb frame but into the studs securing the exterior and interior walls.

Depending upon the gap between the lock edge of the door and the jamb, the security strike plate can be either surface mounted or partially surface mounted in order to reduce access to the latch or bolt while increasing the level of security against forcing the door.

A variation on the security strike is the Sure-Strike that provides bolt and forced entry latch bolt and forced entry protection that works with the end user’s existing deadbolt locks. The Sure-Strike is an oversized strike plate whose larger (1-1/8” diameter) opening contains a number of spring loaded stainless steel pins within an elongated body. This body is designed to extend into a wall stud, providing additional protection against lateral movement.

When the deadbolt extends into the Sure-Strike, only those pins that are pressed against by the bolt are pushed back. The remaining pins stay in place, minimizing the amount of door travel when the deadbolt has been locked. When the deadbolt is unlocked, the Sure-Strike pins spring back into position flush with the surface of the strike plate. The faceplate of the Sure-Strike is manufactured from cold rolled steel.

Latch and bolt protection is important, even if the door or adjacent area is equipped with glass window large enough for someone to walk through. A break-in is more likely to occur through a door that has little or no additional protection. Adding latch protection provides visual deterrent.

The following is a sampling of latch protector product manufacturers. For a more complete list, see the 2010 Locksmith Ledger Security Register.

Don-Jo, P.O. Box 929, Sterling, MA 01564. Telephone: 978-422-3377. Web Site:

Latch-Gard, P.O. Box 425, Wakarusa, IN 46573. Telephone: 574-862-2373. Web Site:

M.A.G. Eng. & Mfg. Co., Inc., 17305 Daimler St., Irvine, CA 92614. Telephone: 800-624-9942. Web Site:

Major Manufacturing, Inc., 1825 Via Burton, Anaheim, CA 92806. Telephone: 714-772-5202. Web Site:

TRIMCO, 3528 Emery St., Los Angeles, CA 90023. Telephone: 323-262-4191. Web Site:

SURE-STRIKE, 2711 LBJ Freeway, Suite 1036, Dallas, TX 75234. Telephone: 888-474-2341. Web Site:


Astragal – a wood molding or metal plate attached to the lock edge of the active leaf (door) of a pair of doors or a single door and a flush jamb. The astragal overlaps the opening and covers a portion of the inactive leaf or jamb.

Deadbolt Protection – See Latch Protection

Latch Protection – a metal plate or combination of interlocking pieces that block access to a latch when the door is shut. Latch protection varies depending upon the door material, location, swing, lock, latch type and strike type.

Reveal – space between the face of the closed door and the end of the jamb.