Can you have a double-sided deadbolt on your house?

I really have to start this answer by saying I am writing for where I live and work. Laws differ in other places but the reasoning for some of this shines through regardless of where you live. Also, in this context your house is where you live and own. Sometimes law distinguishes between owning the house and simply renting it.

First, the law. You can not put a double deadbolt* on a fire exit since people must have an easy path out during an emergency. In Canada, this mean a functioning adult or child above sixish can get out of a room or a building without special tools or knowledge. A key is considered a special tool. Also, after the building reaches a certain size and/or expected occupancy, it must have two or more exits.

Second, more law. If you own your home, you can legally do stupid things.

Finally, the practical. If unblocked exits are good in public places in lowering the number of deaths in fires and other emergencies, then exits are also good in a house. Consider other options before you install a double deadbolt such as a metal grill over a window in the door or installing the deadbolt below the handle so an arm thru the broken window could never reach the inside anyways.

However, you MIGHT consider a double deadbolt in some narrow situations. I ask my customers where everybody sleeps and to think of what is the primary exit if a fire happens at night. You would NEVER put a double dead bolt on this door. You may also want to skip a secondary door. However, I have seen houses with a third and fourth door onto a deck or into the garage. (You would not normally exit in a panic via a garage but that really depends on your particular floor plan.)

If you think sealing a door against a broken window attack with a double deadbolt is worth the risk, then you should also be adding a glass break sensor to that window so your alarm response is instant if it gets broken. Another good idea is to hang a key close to the door so if this door must become the tertiary** exit, then it can be opened quickly. The practical viability of doing this depends on the physical and mental condition of the most vulnerable person living in the house.

Some of the NEVER even consider it situations would include:
• Granny uses a walker
• Toddlers live in the house
• Only one door
• It is a solid door
• The key will be stored in the inside cylinder
• No key will be placed permanently near it

As you can tell, I actively discourage such deadbolts. In fact, most of the time it is a matter of telling the client it can not be done due to codes and our client base will find other solutions. I hope you do too unless it truly meets a critical security need. After all, if fire exits are a good idea in other places, you family and friends deserve them also.


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*This kind of deadbolt is most formally called a double cylinder deadbolt but it is also called a double sided deadbolt or simply a double deadbolt. Regardless of how you say it, the lock is operated by a key from the outside and also by key from the inside. Only a key holder can open the door.

** It means third.

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Laux Myth ... Thoughts From a Locksmith
By MartinB, Found @ http://lauxmyth.blogspot.com/