You do not know how many keys exist
When you move into a home, the previous owner or tenant may have kept copies. So may relatives, neighbors, cleaners, contractors, real estate agents or earlier occupants you never met. Even if everyone involved was trustworthy, keys get lost, passed along and copied. There is usually no way to count them.
That uncertainty is the main reason to change what the keys open. It does not mean anyone is likely to misuse a key, only that you cannot rule it out, and an easy fix is available.
Rekey or replace?
There are two ways to make old keys useless.
Rekeying keeps the lock hardware but changes the internal pin arrangement so that a new key works and the old key does not. A locksmith, or a confident do-it-yourselfer with a rekeying kit, can do this to many common residential locks. It is often cheaper than buying new locks, and a single new key can be cut to operate every lock in the house.
Replacing means installing new lock hardware. This makes sense when:
- the existing locks are worn, damaged or poor quality,
- you want a higher-grade deadbolt anyway (see the article on deadbolt grades),
- the locks cannot be rekeyed because of the brand or design, or
- you are adding smart or keypad options.
Prices vary a lot by region, lock type and how many locks you have, so ask for a quote before deciding. If you hire a locksmith, check their credentials and ask about licensing requirements in your area.
Do it early
Ideally, rekey or replace before or immediately after you move in, since it is easier when the house is empty and there is no pressure from deliveries or movers. Until it is done, avoid leaving valuables near doors, and make sure all deadbolts are actually engaged.
What else to change
Locks are not the only way into a home. At the same time, consider:
- Garage door codes and remotes. Reset keypad codes and reprogram openers, as with any garage remote.
- Alarm codes. Any home alarm system or app account that came with the home should have its codes reset, and the provider should be told the new owners have taken over.
- Smart lock codes. Delete all existing user codes, not just the main one.
- Mailbox, shed, gate and padlock keys. If there is a gate, a gate lock or a separate padlock on a shed, treat them the same way.
- Hide-a-key spots. If the previous occupants left a spare under a rock or in a lockbox, find it and remove it.
Setting up key control
Once the locks are secure, keep them that way with a few simple habits.
- Count your keys. Write down how many exist for each lock. A basic notebook or note on your phone is enough. If a key is missing and cannot be found, consider rekeying again.
- Limit copies. Make only as many as you need. Some keys are marked “Do Not Duplicate” but that is a request, not a physical block, so do not treat it as protection.
- Avoid labeling keys with your address. If keys are lost, a label makes it easy for a finder to know where they belong. Use a code or color instead.
- Skip the obvious hiding places. The mat, flowerpot, fake rock and top of the door frame are well known. If you need to leave access for family, a keypad or a smart lock with temporary codes may be better.
- Use a lockbox with care. A lockbox with a code is better than a loose key, but only if the code is changed regularly and not widely shared.
- Keep a spare with someone you trust. If you do this, record who has it.
- Take back or deactivate access when circumstances change. If a babysitter, contractor or former roommate has a key, ask for it back or rekey when the situation ends.
Renters
If you rent, the landlord or property manager usually controls the locks, and rules differ by location. Some places require lock changes between tenants, but many do not. Ask what was done and whether you may rekey the locks, and follow lease terms if you want to install your own hardware. Do not alter locks without permission, and keep any original parts if you are asked to restore them.
Digital keys and shared codes
Keypad and app-controlled locks make it easier to give each person their own code and cancel it later. This is a real advantage over physical copies. They also have different risks. Whichever approach you use, the principle is the same: know who has access and be able to remove it.
A brief checklist
- Rekey or replace locks soon after moving in.
- Reset garage, alarm and smart lock codes.
- Count and log keys.
- Remove old hiding places.
- Review who holds copies at least once a year.
None of this guarantees that a break-in will never happen, but it does ensure the keys to your home are in the hands you intended.