I've read this good info to share here today about the effective use of deadbolt lock, posted in realestate.com.au:
Correct installation
There are many places that sell deadbolt locks, but unless they’re installed by a professional chances are they won’t do you any good.
Deadbolt locks should always be installed by a expert.
Anatomy of a deadbolt lock
Deadbolt locks have a long, steel bolt that fits inside a hole in your door frame. These holes should be reinforced with a metal strike plate.
In order to be effective, the bolt must fit all the way inside the hole and the hole must have/hit the strike plate [check with author for accuracy]
Otherwise, if someone were to kick your door in to gain access it’s not going to the door that breaks – it would be a door frame that’s compromised by a poorly fitted bolt which allows the door to be opened.
Positioning the lock
Correct placement of the deadbolt lock and the type you install is very important – especially if you have glass panes in your door.
If your door is equipped with a single-cylinder deadbolt lock, an intruder could easily smash the glass and reach inside to turn the knob, thereby gaining instant access to your home.
Double-cylinder deadbolt locks are more secure because they require a key to open.Double-cylinder deadbolt locks prevent this because they do not have the turn knob on the inside and a key is required to open them from either side of the door.
Always act security-minded
No lock will protect your home if you don’t actually use it.
Most people simply turn the lock on their door handle and never bother with securing the deadbolt.
Don’t forget to secure the deadbolt each & every time.For maximum security, always remember to secure the deadbolt lock along with all the other locks you may have on your door.
source: http://www.realestate.com.au/blog/secure-home-deadbolt-lock/
