Police officers seem to prefer double-keyed deadbolts because of added security. It's fairly easy to break into a home with a glass sidelite (window) on the front door. The burglar simply smashes the glass, and then they can reach in to unlock the door.
To lock and open the door from the inside and outside, you'll need a key. People install double-sided deadbolts primarily for security reasons. With a single-keyed deadbolt, for instance, a determined burglar could smash a window to reach inside and use the knob to unlock the deadbolt.
Businesses often use double-cylinder deadbolt locks because they provide more security on exterior doors that have windows. When intruders attempt to break into a building through a window, the key lock on the inside of the door will stop them from entering.
The main advantage of installing double-cylinder locks is enhanced security. That's because doors with adjacent windows or glass panels can be broken, allowing intruders to reach inside and unlock the door manually. This is a significant weakness in terms of commercial break-ins and residential burglaries.
While there is no federal law prohibiting deadbolts requiring two keys, you could violate local codes if you upgrade to a double-keyed deadbolt on even just one door in your home.
For one, double-sided deadbolts are the most secure lock. This is especially important if your front door is located near a window that can be easily opened or broken, or if the door itself is made of glass.
Even though it may take some time to pick a deadbolt, many burglars are well equipped to handle it with ease. Choose a lock that has a high security cylinder if possible. These locks will have a special pin inside of them, which cannot be picked using a standard tool.
CR's take: The Medeco Maxum 11TR503-19 is the strongest deadbolt across all of our lock categories. It's top-notch for drilling, withstands kick-ins very well, and is designed in a way that makes it quite difficult to pick.
Generally, single-cylinder deadbolts are less secure than double-cylinder options.
Deadbolt Lock Disadvantages
Deadbolts are stronger and more difficult to compromise than other locks, but they're not entirely impenetrable. Break-ins can still happen no matter which type of lock your doors have.
1) EVVA MCS
Each key has a complex rounded shape, this coupled with the magnetic element makes it an extremely hard lock to pick. The only way to gain access to the door would be for the key to be cloned, and in that case, a master locksmith would need to get their hands on the original key.
Most police departments do not recommend double deadbolt locks for residential use. You may be adding additional security at the expense of personal safety with a double cylinder dead bolt. For example, you could lock yourself in and not be able to escape in case of fire or other emergency.
Single cylinder deadbolts are quite common in residential homes. Such locks use a key slot on one side with a thumb-turn mechanism on the other side; the key slot generally faces the outside of a door. This system also allows you to unlock and lock single cylinder deadbolts using a thumb turn from the inside.
In the U.S., there is no single comprehensive law against dual-cylinder deadbolts. Individual cities and states have local property and fire codes that may prohibit the use of dual-cylinder deadbolts. The code may prohibit the use of dual-cylinder deadbolts in some buildings and allow them in others.
Due to the nature of the mechanism, a deadbolt will always be more secure than a doorknob. If you're reading this from home I encourage you to do a simple test: If you have a door with both a deadbolt and a doorknob, open it and then lock both locks while the door is open.
Only the most secure deadbolts earn a Grade 1 rating, by incorporating such features as antipick pins, extra-long bolts in extra-tough alloys, and reinforced strike plates with long screws to secure them to house framing.
Schlage and Kwikset are two of the most popular lock manufacturers on the market. Both brands make excellent locks that homeowners can easily install, but Schlage locks tend to offer higher security and reliability and are trusted by big businesses.
Abloy Protec2 PL 330 Padlock
It is one of the only locks in the world that has never been picked. It has a hardened boron alloy steel shackle to provide resistance to bolt cutters (but is not bolt cutter proof). The padlock body is brass and the shackle and body are chrome plated, so it is very rust-resistant.
It is all depending on the deadbolt that you have. If it is a standard lock they can usually just pick it or bump key it. But if it a security lock then the only way that they are able to open it is to drill the lock.
Available in single- and double-cylinder styles, deadbolts are rated according to their strength from Grade 1 to Grade 3. A Grade 1 is the highest grade and provides the most security.
The magnet doesn't make the lock move: Every lock will work differently, but it's typically friction that causes this problem. If a piece of your lock is supposed to move, be sure it can move easily. If it's attached too tightly, your magnet may not be able to move it.
You might perceive that locksmiths are only concerned with providing safe key entry into your house. This is not the case as they also have the skills to open a deadbolt that has been locked from inside. This means that if you are locked out, you do not need to break a window or door to gain entry into your house.