Securing all doors is the first logical step in protecting your home and/or business against burglary. Therefore, the installation of auxiliary locks is a necessary requirement.
It must be understood that no lock, no matter how good, can make a house, store or office burglar-proof. Good locks, however, can be an effective deterrent against break-ins. The more difficult the lock, the less likely a culprit is to attempt or to succeed in breaking into a premises.
Deadbolt locks gets their name from the fact that they only move with a key or thumb turn. They cannot be slipped with a card or shim tool because no springs are attached. You must use a key to lock deadbolts from the outside.
The following points should be considered when selecting a deadbolt:
The bolt should be no less than one (1) inch long when fully extended, and should retain part of the bolt within the mechanism itself. This ensures some degree of strength where the bolt and mechanism meet.
The outside collar surrounding the cylinder should be of substantial construction - not a thin metal that can be easily crushed or ripped open. A slip ring is a feature of some deadbolts that allows the collar to rotate freely and prevents the cylinder from being twisted off with the force of vice grips or a pipe wrench.
It is important that a suitable strike plate be attached to the frame to ensure a strong anchor point for the bolt.
A deadbolt lock is available with a double cylinder and requires a key to lock it from both the inside and outside. This is a useful feature where the inside thumb turn can be reached from a broken or forced window near the lock. A wrap-around door guard is a feature that protects the lock and reinforces the door around the lock. It is available from any locksmith.
Auxiliary locks, such as interlocking bolt rim locks, are commonly referred to as "jimmy-proof" locks. Instead of the normal horizontal bolt, there are two vertically moving deadbolts that lock into a frame-mounted striker so that the lock and striker are firmly interlocked. If it is not necessary to unlock the door from the outside (i.e. the back door of a retail outlet), then the lock can be installed with an inside cylinder only.
Because the striker is mounted on a minimum amount of wood, these locks are ideally suited to wooden frames or in places where there are side lights.
If your door opens outward, you must ensure that your exposed hinges are secured. If exposed hinge pins can be removed, then an intruder can gain entry by swinging the door on the lock after prying open the single hinge.
Ensure that your door is equipped with non-removable hinge pins.
Drill a matching hole in each hinge leaf or remove a matching screw from each. In one hole, insert a screw that is 1/2" longer than the hole is deep. Cut off the screwhead with a hacksaw so that the headless screws will fit into the hole on the opposite leaf when the door closes and will hold the door to the frame even with the hinge pins removed.
Prevent the removal of the hinge pins by drilling a small hole into the hinge and inserting a small steel pin or screw to hold the pin in place.
Fire Emergency Warning:
It is important to consider the safety of all occupants of your home and/or business when installing any double cylinder door lock. Always ensure that an exit is available by leaving the key in the lock when the home or business is occupied.
Even the best locks can be defeated by a method known as "spreading". This occurs when a wedge or jack-like device is inserted between the two door frames. Penetration is successful because doors and frames are purchased as single units and are placed into wall openings provided by the builder during construction. Although the opening between the wall and the frame is braced at the top and bottom with alignment wedges, the mid-sections are often left open, permitting frames to bow under pressure. Solid blocks inserted between these openings will help resist this form of entry.
To strengthen the frame, install 3-4" screws through the doorstop strip and the frame and into the heavier wood of the wall construction. To further reduce an intruder's ability to spread the door frame, the same procedure should be applied to the hinge side.
When considering a deadbolt as an auxiliary lock, attention should also be paid to the strike plate because it bears the brunt or the force applied to the door.
A metal strike plate is installed on or in the door frame and is intended to house and protect the bolt of the lock. A typical strike is only fastened with 3/4" screws. It is important that the desired amount of security provided by the lock is not compromised by a weak strike plate. High-security strike plates are available from any locksmith.
Continuous testing is conducted to improve the strength of strike plates. Two types are currently recommended:
Security strike boxes installed with 2-1/2" to 3" screws provide the additional security of a recessed box which anchors into wall studs and offers strong metal housings for bolts.
Wrap-around strike plates are another way to strengthen frames. They are particularly useful on frames with adjacent side lights where minimum thicknesses of wood are available. This style of strike plate is fastened with screws in two directions.