The market is overflowing with all kinds of doors and with each kind of door there are different locks to choose from. But even the most solid heavy duty door (hard wood and steel) can be broken into if the burglar is really determined because most of them have the tools to do it. One good thing to know is that even the best locks and doors are no competition against crowbars, but there are certain hardware pieces that can act as a warning for a potential burglar and make him choose to break into somebody else’s house.
Concerning doors, most don’t even deserve the name as a hole can quickly be made in them. Avoid hollow doors and most wooden ones (except made from solid and thick wood), doors with windows (or if you must have windows, make them very small, covered with curtains and high enough so that if someone breaks the glass the lock won’t be accessible), doors whose hinge pins are outside.
Your best bet is a door made of steel, but whatever door you choose, make sure it has a peephole capable of offering at least a 180 degree view.
The biggest weakness of a door is the door jamb. If your door only has one lock, quickly install a secondary lock and put an anti-shim plate at the knoblock, but know that this is only a temporary solution and is no match against a well equipped burglar.
Choose good quality, pick-proof locks. Companies from which you can get such locks are Medeco, Fichet or Schlage. Make sure the lock is case hardened (to be drill and smash resistant). Absolutely avoid the spring latch and the key-in-knob type as these can be easily opened with only a credit card, as seen in the movies.
Having double-sided deadbolts installed is a good idea, but a better one is to install a morticed lock, meaning that nothing will be outside the door for the burglar to grab with pliers or whatever tools he may use. And also use a simple guard plate to cover all of the lock except the keyhole. But you must understand that no matter how good a lock is, it can still be opened if the person can tinker with it for enough time. The idea is to make the burglar give up and try to get entry into an easier target.
But what if you have sliding doors ? Always use the safety pin at the top and put a bar to prevent the door from opening. This will make most burglars have a hard time getting past it. Try putting the bar in the middle, wedget halfway down between the sliding door and the wall. If you don’t have one readily available, you can surely get one from a locksmith shop.