Should You Change the Locks After Buying a House? A Locksmith Answers

Short answer: yes, change or rekey every outside lock after you buy a house, ideally the day you get the keys. You have no way to know who still has a copy. Rekeying is usually enough and costs less than new locks. Replace a lock only if it’s worn, damaged or cheap, or if the door has no deadbolt at all. Then change every keypad, smart-lock and garage code.

By Bill String, locksmith and owner of Kwikpick Lock and Safe in Sun City, Arizona. 10+ years, 10,000+ jobs. About Bill

I’ve been a locksmith for more than 10 years and done over 10,000 jobs, and a lot of them start the same way. Somebody just closed on a house, they’re standing in the kitchen with boxes everywhere, and they say, “We got three keys at closing. Is that all of them?”

The honest answer is: nobody knows. Not the sellers, not the agent, not me. That’s why I tell every new homeowner the same thing.

Why you should change the locks after buying a house

Think about everyone who may have had a key to that house before you:

• The past owners, and the owners before them
• Their kids, family members and friends
• Cleaners, dog walkers, pet sitters and babysitters
• Contractors, roofers, painters and handymen
• Neighbors who watered the plants on vacation
• Agents and showing services, on a lockbox key
• On a new build, the construction crews

Most of those people are honest. That’s not the point. Keys get lost, copied, left in junk drawers and handed to the next person. Once you close, the house is yours, and you should be the one deciding who can get in.

Rekey or replace? How I decide on the job

Rekeying means changing the small pins inside the lock so a new key works and every old key doesn’t. The lock stays on the door. You keep the hardware you already have.

Replacing means taking the lock off and putting a new one on.

Here’s how I decide when I walk a house:

• Rekey when the locks turn smoothly, the deadbolts throw all the way, and the owner likes how they look. This is most houses, and it usually costs less. (See what rekeying costs.)
• Replace when a lock is loose, worn, sticking or damaged, when it’s a cheap builder-grade lock on an outside door you care about, or when the owner wants a different style or a smart lock anyway. (See what changing locks costs.)
• Add a deadbolt when an outside door only has a knob lock. That happens more than people think, especially on back doors and the door from the garage into the house.

One more thing to ask for: put every outside lock on one key. If your locks are the same brand and keyway, a rekey can usually make them all work on the same key. One key for the whole house is something nearly every new owner wants once they hear it’s possible.

Which doors to rekey (people miss these)

Everybody remembers the front door. These are the ones people forget:

• The door from the garage into the house. It’s often the weakest lock in the house and the one left unlocked most. If someone gets into the garage, this is the only door left. See securing the garage-to-house door.
• The back door and side doors. Including a walk-in side door into the garage.
• Gates, sheds and mailbox locks if they’re keyed.
• Sliding patio doors don’t use a key you can rekey the same way. Make sure the latch catches, and add a security bar or pin. See sliding door security bars.

Don’t forget the codes

Rekeying only changes which metal key works. It does nothing to a code. Change these too:

• Keypad deadbolts and smart locks. Change the codes, and remove the old owner’s account or app access. If you can’t, do a factory reset following the lock’s instructions.
• The garage door keypad and remotes. Set a new keypad code and clear the old remotes from the opener’s memory, using the opener’s manual.
• The alarm system, if there is one. Change the master code and get the account moved to your name.

What about a brand-new house?

New construction still needs a rekey. Builders often use construction keying so crews can get in while the house is being built. On top of that, the house may have been shown to buyers for months. Rekeying makes sure only your keys work, from day one.

When to do it

The best time is the day you get the keys, before your things are inside. If that can’t happen, do it within the first week. Every day before then, someone you’ve never met may still have a working key to your house.

If you’re moving in over a few days, start with the doors people actually use: front door, garage-to-house door and back door. Then do the rest.

Can you do it yourself?

Often, yes. Common brands can be rekeyed with a kit, and some have a built-in rekey feature. I have free how-to guides if you want to try it: how to rekey a lock and how to rekey a lock to match a key you already have.

A locksmith is worth it when you have a lot of doors, mixed brands, locks that are hard to take apart, or you want everything on one key in one visit. If a door has no deadbolt and you’re handy, here’s the full install:

Your first-week lock checklist

1. Rekey or replace every outside lock, including the garage-to-house door.
2. Put the outside locks on one key, if you can.
3. Change keypad, smart-lock, garage and alarm codes, and remove old app users.
4. Check that every deadbolt throws all the way into the frame.
5. Latch every window and note any that don’t lock.
6. Add a bar or pin to sliding patio doors.
7. Start a key log: every copy you make, and who has it.

Want this as a printable? The free Lock-Check Checklist and the new homeowner checklists walk you through it door by door.

Common questions

Should I change the locks after buying a house?

Yes. You can’t know how many keys the past owners, builders, cleaners, contractors and neighbors still have. Rekey or replace every outside lock as soon as you get the keys.

Is it better to rekey or replace locks on a new house?

Rekey when the locks work well and you like them. It’s usually cheaper and makes every old key useless. Replace locks that are worn, loose, damaged, low quality, or a door that has no deadbolt at all.

How soon after closing should I change the locks?

The day you get the keys, or before you move your things in. If that isn’t possible, do it in the first week.

Do I need to change the locks on a brand-new build?

Yes. New homes are often built with construction keying so crews can get in during the build. Rekeying makes sure only your keys work.

Can I rekey the locks myself?

Often, yes, if the locks are a common brand and you have the right kit or the brand’s rekey tool. A locksmith can do a whole house quickly and make every lock work on one key.

Does rekeying change a keypad or smart lock code?

No. Rekeying only changes which metal key works. Change the codes and remove old app users separately, following the lock’s instructions.