Generally speaking, only deadbolt locks should be used on any exterior door, whether residential or commercial. They provide superior security, as they are not spring loaded and have a rigid bolt that extends into the strike plate. The two basic types are as follows;
- Horizontal deadbolts - should be at least one inch long when extended into the strike plate. They are activated by either a key (exterior cylinder) or thumb latch on the interior. Double-cylinder locks that are key operated on both sides are recommended for commercial applications, especially when the mechanism is within one metre of any type of glass.
- Double-cylinder locks are generally not recommended for residential use as they may impeded quick emergency exit should a life threatening situation occur; such as a fire.
However, one must remember that when a single-cylinder lock with an interior thumb latch is within one meter of exterior glass, then that glass should be reinforced by some type of anti-shatter film or laminate.
- Vertical deadbolts – also provide excellent security. It mounts on the inside of the door and has two vertical bolts, which interlock with the eyeholes, or sockets of a specially designed strike plate. This prevents the bolt from being pried away from the doorjamb.
One weakness of this lock is the length of the screws that hold it to the inside of the door. This can be overcome by replacing the screws with carriage bolts. These bolts go all the way through the door and the lock and are secured with nuts on the inside. The only thing visible on the exterior are the tamper-proof heads of the bolts, which in and of itself can be a visible deterrent, alerting an intruder that a heavy-duty locking mechanism is in use.
The lock cylinder, which is the part of the lock in which the key is inserted, is susceptible to removal by vice grips. To prevent this from happening the lock cylinder should be beveled, have a rotating metal collar or both – a beveled rotating metal collar. This device – often referred to, as a “spin ring” will prevent the lock cylinder from being rotated right out of the door by a set of vice grip pliers.
While having good deadbolt locks and reinforced strikes plates go along way toward improving security, attacks against them can be prevented by the use of a latch guard.
- Made of metal, these devices protect the thin space between the door edge and jamb when the door is closed. Without a latch guard, there is always enough room in the space for an intruder to attempt to pry the door open with a crow bar or similar tool.
- Latch guards can come or be made into various lengths but should be large enough to protect the latch area of the lock, usually 3 – 4 inches above and below the lock. Some latch guards found on exterior steel clad doors cover the entire door from top to bottom. This is especially recommended for secondary doors; usually side or rear service doors that have little or no natural surveillance afforded to them via neighbours or passers-by.
Escutcheon Plate / Lock Reinforcer
This is highly recommended for any exterior wood door or an interior wood door desiring added security. This metal device wraps around the door like a sleeve around both sides of the door and door edge and protects the wood near the lock mechanism from attack.
- Date modified: