Rekey or replace your locks? How to choose, door by door

How does a rekey work?

A standard house lock has a cylinder with a row of small spring-loaded pins of different lengths. The right key pushes each pin to exactly the right height, and the cylinder turns. To rekey, a locksmith takes the cylinder out, replaces those pins with a set cut for a new key, and puts it back.

What you end up with:

• The same lock, handle and deadbolt on the door.
• A new key that works.
• Every old key, including copies held by the previous owner, past tenants or a contractor, no longer turns the lock.

A rekey doesn't make a lock any stronger. It controls who has a working key, not how well the lock resists force.

When is a rekey the right call?

When the hardware is fine and the keys are the problem:

Lost keys and not sure if a rekey is worth it? Our guide on changing locks after losing keys walks through how to judge the risk.

Renting? Talk to your landlord before changing or rekeying a lock on a rental unit. Our post on lock changes for Nova Scotia landlords and tenants explains where to find the rules.

When should the lock be replaced?

When the lock itself is the problem:

• Salt and damp have got to it. Near the harbour and along the coast, salt air works into exterior cylinders. Grit, stiffness, a key that has to be wiggled, or green and white crust around the keyway all point to corrosion that a rekey won't cure.
• It's worn out. The deadbolt drags, the handle wobbles, or you have to lean on the door to lock it. Some of that is door alignment, which also shifts as wood swells and shrinks through freeze-thaw cycles, but some locks are simply done.
• It's damaged. Forced, kicked, drilled or bent after a break-in attempt.
• You want an upgrade. A heavier deadbolt, a keypad or smart lock, or a high-security cylinder with restricted keys.
• It doesn't match. One odd brand or keyway that can't share a key with the rest.

If you're replacing for security, remember that the door frame usually gives out before the lock does. Our guide on securing your front door covers the strike plate and long screws that matter more than the brand on the deadbolt.

Can one key open all my doors?

In most homes, yes. Keyed alike means the front door, back door, side door and the door from the garage into the house all open with the same key. It's one of the most common reasons people rekey after a move.

What decides it is the keyway, the shape of the slot the key slides into. Different brands, and sometimes different lines from the same brand, use different keyways. Locks with compatible keyways can be rekeyed to one key. A lock with a different keyway may need its cylinder or the whole lock replaced to join the set. We check each door and tell you which.

What about older locks?

Most rekey without trouble. An older lock from a common brand with a standard pin tumbler cylinder rekeys the same way as a new one. It gets harder when:

• the cylinder is badly worn or corroded, so a new key won't run smoothly
• the lock is discontinued or unusual, and pins or parts are hard to source
• the lock is damaged, in which case it should be replaced anyway

An older lock in good condition is often worth keeping, especially on a heritage home where the hardware suits the door.

Is a rekey less work than a replacement?

Usually. With a rekey the lock stays put and only the pins change, so there's no new handle or deadbolt to buy and fit. A replacement means new locks, fitting them, and sometimes adjusting the door or the strike to suit.

That's why, when your locks are in good shape, a rekey is what we suggest first.

Landlords with several units

The same logic applies at scale. A rekey at every turnover is the routine, and a key log saves trouble later. Our guide on rekeying between tenants sets out the turnover steps.

Two questions for every door

Stand at each exterior door and ask:

1. Does this lock turn smoothly in wet and cold weather alike? If not, replace it.
2. Do I know everyone who has a key? If not, rekey it.

A smooth lock with unknown keys needs a rekey. A rough lock needs replacing whoever has the keys. When you're ready, see rekey your locks. Have every key you own on hand, decide whether you want one key for all the doors, and we'll handle the rest at your door.

The printable move-in lock checklist below takes you through every door and key in about ten minutes.