Home Safety : Door System Security

Home Safety : Door System Security

Each of the components of the door system requires individual consideraiton with respect to security. These considerations include the lock on the door, the strike plate on the frame and the hinges on the door.

Key-In-Knob With Anti-Shim Device

Spring loaded latches can be either mortised (set into the door) or rim mounted (set on the door). Rim mounted spring latches usually used as auxiliary locks, but provide little security because the latch is short and the jamb can be spread or the screws can be popped out by kicking the door.

Some manufacturers add security features such as anti-shim devices on the key-in-the-knob devices. If properly installed, these devices may prevent skipping the bolt with a credit card. However, the knob can be easily wrenched off or the jamb can be spread to release the short spring bolt.

Key-In-Knob Latch

The majority of all doors are equipped with a standard key-in-the-knob latch which provides little or no security. Note the term “latch,” not lock. These devices have a spring which holds a latch in place. These latches can be defeated by wrenching the knob with hands or vice grips, using credit cards to slip the spring latch, kicking the door, or spreading the frames.

Deadbolt Locks

  • Single Cylinder Deadbolt Lock – Has a thumb turn on the interior side. They are convenient to use and may speed up the exit process in the event of fire. If used near a window they can be opened easily by breaking the window and reaching through to the inside to turn the thumb turn. This type of deadbolt lock does not prevent the burglar, once inside, from taking your property out through the door.
  • Double Cylinder Deadbolt Lock – Utilizes keys on both sides of the lock. This type of lock should be considered if there is glass window within 40″ inches (arms reach) of the lock. However, this type of lock does present a potential fire escape hazard and may be against local building and/or fire code. This type of deadbolt lock can delay a burglar that wants to use the door to remove your property from you home. If this lock is used, make sure the key is not left in the inside part of the lock. All members (adults and children) of the house need to know where the key is kept and also how to use it in order to get out of the house. When you buy a deadbolt lock, MAKE SURE:
    • The bolt extends at least one (1″) inch into the front edge of the door
    • The strike plate is attached through the trim to the door frame with screws at least three (3″) inches long
    • It has a rotation case hardened shroud that prevents it from being twisted off with a pair of pliers or other tools
  • Rim Mounted Locks – Surface mounted or rim mounted deadbolts, both vertical and horizontal bolts, also provide good security. They mount on the surface of the door and are easy to install. This type of lock is less expensive than single or double cylinder mortised locks.

The surface mounted deadbolt locks have either a vertical or a horizontal bolt. The vertical drop has an interlocking principle which locks the bolt into the strike plate.

Key Control

  • As many as half of all burglaries take place without forced entry. Many times the burglar uses a key. Be sure your keys don’t fall into the wrong hands.
  • Never carry identification on your key ring or holder.
  • Re-key all locks when you move into a new house or apartment.
  • Know who has keys to your home.
  • Do not give keys to maintenance or delivery people. If you must leave a key behind, leave it with a trusted neighbor. Make sure that each member of your family knows where his or her key is.
  • Never hide a key outside. Burglars know all the hiding places.
  • Do not hang keys on hooks within plain view inside your house.

Strike Plates

The weakest point of a good lock may be the strike plate, which secures the bolt when the door is locked. Because of the way the frame is constructed, the strike plate must be reinforced. The door frame is set into an opening at the time of construction, and after the frame is squared, there is air space between the door frame and door buck (2 x 4 next to the opening for the door).

With the addition of the reinforced strike plate, the door jamb is not likely to split when the door is kicked.

To increase security, the air space between the door frame and door buck must be bridged so that the locking system is secured to a structural member, not the trim.

Thin gauge metal strike plates should be replaced with heavy duty strike plates secured with number 12 three (3) inch wood screws. This adds protection to the jamb and is relatively inexpensive. If the frame appears weak, further security can be added by installing the long, high security strike plate or a high security strike box. These should be secured with number 12 three (3) inch wood screws.

For doors installed next to masonry walls where there is not a door buck, lead anchors must be placed in the wall and the strike plate attached to the lead anchors.


Hinges are often installed with the same 3/4″ inch screws as the common strike plates. Replace these with three (3″) inch fully threaded screws so the hinges are anchored to the sub-frame.

In some cases the hinges are installed in such a manner that the hinge pins are exposed to the exterior and an intruder may attempt to remove the pins in an effort to gain entry.

Hinges can be pinned by installing a partially threaded screw into the frame side of the hinge. The unthreaded portion of the screw is left exposed and the head of the screw is cut off. A corresponding hole is drilled into the door and hinge on the opposite side, so when the door is closed the exposed portion of the screw fits in to the door. This will prevent the door from being lifted out

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