The Importance Of Deadbolts Explained

Share on Facebook

January 21, 2017

A deadbolt is a locking mechanism that can only be opened by rotating the lock cylinder with the key.

Deadbolts therefore make a door very resistant to entry without the correct key.  This is why you must have one; for safety.  Often, deadbolts are used to complement a spring-bolt lock on an entry door to a building.

A cylinder operated deadbolt may be either single or double cylinder.  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.  Double cylinder locks will accept a key on both sides and don’t require (and often don’t have) any twist knob.  This prevents unwanted unlocking of the door by forced access to the interior twist knob.

Double cylinder locks are sometimes banned from areas because they can be difficult to open from the inside and violate fire safety regulations.  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.

A 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).

Other types of deadbolts include:

– Push-button deadbolt (mechanical or electrical)
– Single cylinder with removable thumb-turn
– Classroom-function (thumb-turn only unlocks door)
– Exit-only function (no external cylinder)

The double cylinder design raises a safety issue.  In the event of a fire, occupants will be prevented from escaping through double-cylinder locked doors unless the correct key is used.  This is often an avoidable cause of death in house fires.  The risk can be minimized by securing the deadbolt only when there are no occupants inside the building, or leaving the key near the keyhole.  Some fire departments suggest putting the key on a small nail or screw near the door at floor level, since the cleanest air is at floor level and you may be crawling to get to the exit.

Note that single cylinder dead locks (with an unlocked twist mechanism on the inside of the door) do not have this problem, and therefore are most commonly used on fire exits.  Some areas have fire safety codes that do not allow a locked exit.

Feel free to stop into Builder Supply Outlet or the Edge Showroom with any home improvement questions you may have regarding deadbolts, locksets, home safety or anything else.  Or call us anytime at 1-708-343-3900.  You can also make an appointment to meet with one of our designers at no charge by clicking here.