This is often an avoidable cause of death in house fires. In the event of a fire, occupants will be prevented from escaping through double-cylinder locked doors unless the correct key is used.

The double cylinder design raises a safety issue. – Exit-only function (no external cylinder) – Classroom-function (thumb-turn only unlocks door) – Single cylinder with removable thumb-turn – Push-button deadbolt (mechanical or electrical)

Some lock manufacturers also have a “lockable” knob a key is always needed on one side (usually external), and a twist knob can be used on the other (internal), unless a button has been pressed, in which case a key is also needed on the internal side.Ī subset of the standard deadbolt is the vertical deadbolt, which resists jimmying (when an intruder inserts a pry bar between the door and the jamb and attempts to pry the bolt out of the door). This prevents unwanted unlocking of the door by forced access to the interior twist knob.ĭouble cylinder locks are sometimes banned from areas because they can be difficult to open from the inside and violate fire safety regulations. Double cylinder locks will accept a key on both sides and don’t require (and often don’t have) any twist knob. A single cylinder deadlock will accept a key on one side of the lock, but is operated by a twist knob on the other side. Often, deadbolts are used to complement a spring-bolt lock on an entry door to a building.Ī cylinder operated deadbolt may be either single or double cylinder. This is why you must have one for safety. The Importance Of Deadbolts Explained Share on FacebookĪ deadbolt is a locking mechanism that can only be opened by rotating the lock cylinder with the key.ĭeadbolts therefore make a door very resistant to entry without the correct key.

Deadbolt lock mechanism