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.
Both sides of a double-cylinder deadbolt have key-entry locks. In a home with a double-keyed deadbolt lock, a person inside is seeing a keyhole where a knob would be seen by a person with a single-key deadbolt. To lock and open the door from the inside and outside, you'll need a key.
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.
However, the major drawback of a double-cylinder deadbolt is that it can be a safety hazard in the event of an emergency—such as a fire. Because a key is required on both the inside and the outside, occupants may not be able to quickly and easily escape if the key is not readily available.
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.
To put it more plainly, twice as many deadbolt locks does not equal twice as secure a door. Adding an extra deadlock only slightly increases the door's resistance to being rammed in (i.e. kicked) by force. In fact, it may be as little as a ten percent or less increase in the psi of force needed.
While the single-cylinder deadbolt only features a locking mechanism requiring a key on one side, the double-cylinder deadbolt has it on both. This means that a key will be required to turn the lock both on the inside of the door and the outside. This is the main difference between these two types of deadbolts.
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.
Basic Cylinder Locks
Deadbolts use a solid piece of metal to secure the door, while standard cylinder locks use a spring to help make it easier to lock the door. Unfortunately, the spring does not provide much security and it can easily be forced. Deadbolts, however, are still vulnerable to lock picking.
In combination with your deadbolt, your door will put up a fight against even the most forceful kicks. They're also tamper-proof and will protect your door against lock picking and lock bumping. Even if someone steals or copies your key, they won't be able to get in.
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.
The answer: One sturdy lock is enough to secure a front door. If installed correctly, a high-quality lock is all you really need. You always have the option of adding a second lock as an extra layer of protection — but there are potentially more productive measures to take.
Double-cylinder deadbolts can be used with a key from both sides. Vertical deadbolts operate similar to single and double deadbolts, but the lock moves up and down instead of horizontally. This orientation is more resistant to forced entry via prying with a tool such as a crowbar.
Though the double-cylinder deadbolt is technically more secure, single-cylinder deadbolts are the better option for most homeowners. This is because when the double-cylinder deadbolt is locked, a key would be required to exit, which becomes a safety hazard in the event of a fire.
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.
A double cylinder deadbolt lock or a single cylinder deadbolt lock without a turnpiece may be used in “Group B” occupancies as defined by the California Building Code.
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.
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.
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.
Bump-Proof Locks
These often come with a “UL 437” rating and the locks themselves have small, unique markings near the keyhole. These high-security locks don't rely on the pin tumbler locking mechanisms and are designed to be nearly impossible for burglars to pick or bump.
Locks to Secure Your Home
Caution: the use of a double-cylinder deadbolt lock can be a fire hazard. While occupied a key should be left in the lock and all children should be trained in the use of the lock and all other fire prevention methods.
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.
Double Cylinder Deadbolts have a keyed cylinder on both sides. This is a good option for doors with glass or windows since an intruder can't break into the door even if the glass/window is broken.
A single-cylinder deadbolt is the most common type. It requires a key to operate the lock from the outside, but has a thumb-turn on the inside. A double-cylinder lock requires a key to operate the door from either side.