A move, a tenant handover, a staff departure, or a set of keys nobody can account for. Most lock changes are not about a broken lock — they are about not knowing who can open the door. That distinction matters, because it frequently means the right answer is cheaper than the one you came here to ask for.
Changing the cylinder is usually the job, not the whole lock
When people say they need the locks changed, what they almost always need is the cylinder changed. The distinction is worth understanding because it is the difference between a modest bill and a large one.
The cylinder is the part the key goes into. Swap it and every key issued before that day stops working, while the lock body, the handles, the security gate and the finish stay exactly as they were. On an older house where the hardware is part of the character, or in a complex where the body corporate regulates anything visible, that matters twice over.
A full lock change is the right answer when the mechanism itself is worn out, when the existing hardware was never suitable for the door, or when a door has been forced and the case is damaged. Those are real cases, and they are the minority.
The four moments worth doing it without hesitating
Taking transfer of a property. Nobody can tell you how many keys exist for a house that has changed hands — previous owners, the agent, contractors, domestic staff, a tenant, a neighbour who watered plants. None of them a threat individually, and collectively an unanswerable question.
The end of a tenancy, for exactly the same reason and on the same logic. Handover day is the cheapest moment, because the unit is empty and nothing has to be worked around. If you are shut out while reading this, it is a house lockout and it is worth phoning rather than reading.
A set of keys lost with something on the ring that identifies the address — that one is urgent rather than convenient. And a change of the people who legitimately hold keys: staff, a cleaning service, a contractor who has finished. Where several doors and several people are involved, master key systems do it properly.
Keying alike, and the trade-off nobody mentions
Most households carry more keys than they need: a front door key, a back door key, a security gate key, a garage key, something for a complex gate. All different, all on one ring, none labelled.
Keying alike solves that during a cylinder change at very little extra cost, because the cylinders are open anyway. One key opens every external door, the ring gets smaller, and nobody stands in the rain trying four keys in the dark.
The trade-off is worth stating rather than glossing over. One key for everything means one lost key affects everything, and anybody handed a key for one purpose can open all of it. Where somebody needs partial access — a domestic worker who reaches the house but not the store room, a tenant in a cottage — the answer is a proper suite rather than keying alike.
What you should be handed at the end
A count. How many keys were produced, and who has each one, written down rather than remembered. It sounds bureaucratic for a house and it is the single most useful thing anybody does on the day, because in two years it is the only thing that answers the question honestly.
The old cylinder, if you want it, and a straight answer about whether the hardware it came out of is worth keeping. Where an original mortice lock is better made than its modern replacement, we will say so rather than sell you a new one.
And a door that locks properly with the vehicle gone. If a part is needed, the property is made secure and we come back rather than leaving you with an opening that works and a lock that no longer holds.
Where this is done, and what it costs to delay
Cylinder changes are done across Rivonia and the surrounding Sandton suburbs of Johannesburg, Gauteng, and the overwhelming majority are booked rather than urgent — which is also the cheaper way to have it done.
The exception is keys lost with something on the ring that points at an address. That is a same-day job rather than a decision to sleep on, because somebody has a working key and knows where it fits.
The cost of delay in every other case is not dramatic; it is simply that the unknown stays unknown. A property where nobody can say how many working keys exist is secured against everybody except an unknown number of key-holders, and that remains true for as long as it is postponed.
Doing the whole property rather than the obvious door
The most common mistake is changing the front door and stopping there. A key ring almost never carries only a front door key, and whatever else was on it still works.
Write the list before anything is quoted: back door, security gate, garage side door, store room, outbuilding, a padlock on a garden gate, a complex pedestrian gate, an office. On the larger stands around Sandhurst, Atholl and River Club that list runs longer than people expect.
Doing all of them in one visit shares the callout rather than paying it repeatedly, and it is the natural moment to decide whether they should take a single key. Where different people need different doors, a suite does that properly instead of with more metal.
What it costs, and what makes it cost less
A cylinder change is a fraction of the price of replacing a lockset, because only the part that decides which key works is swapped. On a standard door it is a short job.
The saving that matters more is doing every affected door in one visit, because the callout is the fixed cost of any attendance. A front door, back door and security gate together cost far less than the same three jobs across a year.
And the hour: a booked weekday morning costs meaningfully less than an evening callout for identical work. The only version of this that genuinely cannot wait is keys missing with something on the ring pointing at your address, which is an emergency locksmith call the same day.
What to ask for when you book one
Four things, and asking for them by name makes the quote comparable and the job better.
That the cylinder be measured so it sits flush rather than protruding, because protrusion is what makes a Euro cylinder easy to snap and measuring costs nothing. That the strike plate and its screws be looked at while the door is open anyway. That every affected door be done in the same visit so the callout is shared.
And that you be handed a written count of the keys produced with a name against each one. That last item is the one nobody asks for, and it is the only thing that answers the question honestly in two years' time.
A note on hardware quality
Not all cylinders sold as replacements are equal, and the cheapest option is frequently a downgrade on what is already fitted.
On an older house the original mortice lock is often better made than a budget modern lockset, and replacing it wholesale is a step backwards dressed as an improvement. Where that is the case you are told, rather than sold the replacement.
Where a genuine upgrade is worthwhile — an anti-snap cylinder correctly measured, a reinforced strike plate — it is quoted as an option with a reason attached rather than added silently. That reasoning is set out under high security locks.