Rekey or replace your locks

What rekeying actually does

Inside a pin tumbler lock, each chamber holds a spring, a driver pin and a key pin. The correct key lifts every key pin to exactly the boundary between the rotating plug and the fixed housing, and the plug turns.

Rekeying takes the plug out and swaps the key pins for a different set of heights. Now a different key lifts them to that boundary and the old key does not. Nothing else changes. The same lock, the same finish, the same screws, the same door.

It takes a locksmith around ten minutes per cylinder and the parts are a few pins worth a few cents.

That is why rekeying is the right answer far more often than replacement. Most people asking to change their locks do not have a hardware problem. They have a key list problem, and this is the tool for that.

When rekeying is the answer

You just moved in. You have no idea how many keys exist or who has them, and the previous owner probably does not either. Contractors, cleaners, a lodger, an ex partner, a neighbour holding a spare. Rekey everything on day one.

A tenant moved out. Rekey between every tenancy without exception. Keys get copied and returning the key you were given proves nothing.

You lost a key. If it had anything identifying the address on the ring, treat it as compromised.

A relationship ended, a housemate left, an employee left, a contractor finished. Same situation, same answer.

You have too many keys. If the front door, back door and garage all take different keys, one visit can key all three alike.

When replacement is the answer

The lock is worn or failing. A key that has to be jiggled, a cylinder that binds, a bolt that will not extend fully, a knob that turns loosely. Rekeying a failing lock gives you a failing lock with a new key.

The grade is wrong for the door. Most homes ship with Grade 3 hardware, the lightest of the three ANSI grades. A Grade 1 deadbolt survives ten hammer strikes and two hundred and fifty thousand cycles against a Grade 3's two strikes and a hundred thousand. On a front door that difference is worth the fifty dollars.

You want keys that cannot be copied. Rekeying uses the same keyway, and a common keyway blank is available in every hardware store. Real key control needs a restricted or patented keyway, which means new cylinders.

The deadbolt throws less than one inch, which means it is not reaching enough material in the frame to matter.

Or you want a keypad or a smart lock, which is a different product rather than a different key.

What each costs

Rekeying is roughly 20 to 40 dollars per cylinder, plus the service call of 35 to 100 dollars. So one lock might be 75 dollars all in and six locks might be 200, because the call out is paid once.

That is the point worth understanding. Rekeying gets dramatically cheaper per door as you add doors, so if you are going to do the back door eventually, do it now.

A replacement deadbolt supplied and fitted runs 130 to 300 dollars depending on grade and whether the door needs boring. A knob or lever set is similar.

A restricted keyway cylinder is more, commonly 90 to 200 dollars per cylinder, because you are buying into a controlled supply chain rather than just buying a lock.

When you are quoted, ask what the total is for all the doors together. Locksmiths expect that question and the number is usually better than people assume.

The upgrade worth asking for while they are there

Ask the locksmith to look at the strike plate. On most homes it is a thin plate held by two three quarter inch screws that bite into the door jamb, which is a thin board nailed to the framing.

A kick goes straight through it and splits the jamb, and the lock is irrelevant because it was only ever holding a decorative board.

A reinforced strike box with four three inch screws driven through the jamb into the structural stud changes what has to break. It costs a few dollars in parts and a few minutes of labour, and it does more for the door than upgrading two grades of lock.

While they are there, ask them to look at the hinges too. Two three inch screws per hinge into the stud is the same idea on the other side of the door, and nobody ever does it.

If the door opens outward, ask about non removable hinge pins, because otherwise the hinge side can be taken apart with a screwdriver whatever the lock is doing.