After having some security incidents in our building, we have decided to change the locks and we are looking at a solution whereby we (co-op board) can give out to residents keys that cannot be duplicated by them. Our building has 16 units and we were thinking on handing out 3 keys per unit (total of 48 keys).

Can anyone recommend a solution to meet the above requirement?

2 Answers 2


What you need is a high-security lock and key system like Medeco or Mul-t-lock. There are others like it, these are just the two I am most familiar with. Both of these systems support master-keying and also cannot be copied. With both systems, the locksmith is issued a "keyway" whereby each locksmith can only produce a specific set of keys.

  • 2
    High security lock companies like those mentioned typically offer interchangeable cores so locksets can easily be re-keyed without the need to remove and disassemble the lockset. The cores are removed in seconds with a special key, for which possession obviously must be strictly controlled as any other master key would be.
    – bcworkz
    Jun 23, 2013 at 17:49
  • I like this solution, my only concern now is that I have just noticed that the mailman delivers the letters after the first door is opened and I do not know if the lock that we will install will have to be compatible with their Master...
    – macutan
    Jun 23, 2013 at 22:57
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    This can avoided by installing a lock/key box. At least in the U.S. You purchase and install a small USPS specific box by the door. The US Postal service installs the lock. All local letter carriers have an "ARROW" key that will fit the lockbox. A door key is kept in the box, it is usually attached to a chain to prevent loss. The letter carrier would open the lockbox unlock the front door with the key and return it to the box. This will not help with FedEx or UPS. Contact your local PostOffice with any questions.
    – mikes
    Jun 25, 2013 at 21:47

You may want to consider keyless entry systems. The cards can be programed to allow or deny access. Once a conventional key is issued it will work until the lock is changed. A keyless system can disable individual cards in the event of loss or theft. The initial cost may seem high but if you are rekeying locks and making 48 copies a couple times a year it may be cost effective in the long term. Occupants can issue cards to service or contract vendors and have them disabled if not returned. Some systems can limit entry to specific times only.

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    Do keep in mind the power requirements of such a system, and it's failure modes when it loses power. If there's batteries (and there should be), then don't forget that changing batteries is now a maintenance item for the building. I think it's a good solution, just don't forget it's downsides. Jun 22, 2013 at 11:56

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