Rekey or replace? How to decide

The difference, in one paragraph

Rekeying changes the pins inside the cylinder you already own, so every old key stops working and a new key starts. The hardware on your door does not change. Replacing means new hardware: a new lock body, cylinder and often new door furniture.

For the large majority of people, the thing they actually want is “make the old keys stop working”. That is a rekey, and it is the cheaper of the two by a wide margin.

When rekeying is the right call

• You have just moved in. The most common reason, and the best money you will spend in settlement week. You have no idea how many keys to that house exist — previous owners, their children, a cleaner, a tradesperson, an ex-partner, an agent, a neighbour who fed the cat in 2019.
• A tenant has moved out. Routine turnover work, and cheaper than replacing hardware at every changeover.
• A key has gone missing. Lost, stolen, or simply never returned.
• A relationship has ended. Quick, quiet, and no new hardware to explain to anybody.
• Too many keys exist. Housemates, trades, old cleaners, copies cut years ago for people you have forgotten.
• You want one key for the whole house. If your cylinders are compatible they can be keyed alike — front, back, garage, side gate all on one key — for very little more than rekeying them separately.

When replacing is the honest answer

• The hardware is worn out. A cylinder that binds, a key you have to lift the door to turn, a deadbolt that does not fully throw. Rekeying a dying lock buys a short reprieve and no more.
• It was forced. After a break-in, damaged hardware gets replaced, not re-pinned.
• It is genuinely out of date. A cylinder from the 1970s or 80s can be rekeyed perfectly well and still be the weakest point on the door.
• There is no deadbolt at all. A latch that can be slipped is not a lock. This is common on side and laundry doors and it is where a lot of break-ins actually start.
• You want a restricted key system. Controlling who can cut a copy requires different hardware — it cannot be retrofitted into an ordinary cylinder.

The thing rekeying does not do

This is the part worth being clear about, because it gets glossed over. Rekeying makes old keys useless. It does not make a weak lock strong. If your front door is running a tired cylinder from decades ago, rekeying it means the old keys are dead and the lock is still the weak point on the house.

A locksmith who tells you that, rather than quietly taking the smaller job, is doing their actual job.

Which doors people forget

Almost every house is well secured at the front and casual everywhere else. Before you book anything, walk around and look at:

• The laundry or side door — very often a latch and nothing more.
• The garage personnel door, especially where the garage connects to the house.
• The rear gate, particularly on terraces with laneway access.
• Sliding doors, which frequently have a lock that stops the door sliding but not the door being lifted out.
• Windows on the ground floor and anything reachable from a flat roof.

Fixing the weakest of those usually improves the security of the house more than anything you could do to the front door.