Dead bolt locks are locks which cannot be forced in the traditional ‘credit card’ way because they present a solid face through any door frame gaps. Dead bolt locks are among the most secure of all locks for domestic purposes. It is easy to forget that a latch lock is easy to open because it is easy to close – no key required.
Main Access Doors
The most obvious places for a dead bolt lock are the front and back doors. The front door lock should be operated by a security key that requires being turned through 720º before the door is dead-bolted. Ideally you should fit two dead bolt locks, one about a third of the way up the door and the other at the top of the door. The tongues of dead bolt locks can be secured in the door frame or in an iron hasp secured to the door frame. A tongue that is secured in the door frame requires the lock to be installed in the door which can be difficult with some styles of door – metal doors especially
From inside the house dead bolt locks are operated either by pressing a button and sliding them open or by pressing down on a knurled wheel and winding them open.
Secondary Access Doors
If you have a garage and a cellar with access to the house you should fit a dead bolt lock to each of the doors. Often the most vulnerable door is the one that you don’t lock very often. Doors into the house from the cellar and the garage are often thought to be safe because they are protected by other doors. If the door from the garage is relatively flimsy it might make more sense to fit a dead bolt lock to the garage door, one towards the bottom of each side.
Windows that can elevate should be fitted with dead bolt locks. These locks fit through the side of the window into the window frame so that the window cannot be raised. They can be operated by a security coded key but are more often operated by an Allen key
If your dead bolt lock key does not need to turn through 720º (ie. two full revolutions) there is a good chance that it will be vulnerable to a very simple lock picking process called bumping.
Bumping a dead lock simply involves using a cut down key of the right type and giving it a sharp tap after inserting it into the lock. The sharp tap displaces the lock tumblers and the cut down key is able to open the door.
Before installing any dead bolt lock make sure that it is proofed against bumping.
Even some 720º locks can be bumped so it is worth the expense to pay a little extra for home security and get locks that are totally secure. If you already have dead bolt locks fitted, ask about a special aerosol preparation that can be applied to them to make them secure.