Master key systems and keyed-alike locks: how they work and how to plan one
The short answer
A master key system gives each lock or group of locks its own key, plus a master key that opens all of them. Keyed-alike locks all open with one key. If everyone should open every door, key the locks alike. If some people should only open some doors, you need a master key system. Both usually start with a locksmith surveying the site.
The terms, explained
- Change key
- The key that opens one lock (or one group of locks) only — for example, one office.
- Master key
- A key that opens every lock in the system, or every lock in one section of it.
- Grand master key
- In larger systems, a key above the master keys. It opens every section, while each master key opens only its own section.
- Keyed alike
- Every lock opens with the same key. There is no hierarchy — every key-holder can open every door.
- Keyed to differ
- Every lock has its own key, and no key opens more than one lock. This is how most locks are sold.
- Rekeying
- Changing the pins inside an existing cylinder so it works with a different key.
- Restricted key profile
- A key blank that is not freely available, so copies can only be ordered through an authorised locksmith or supplier.
- Key schedule
- The list of every door, which key opens it and who holds each key. It is the plan for the whole system.
Which one does your building need?
Keyed alike suits a home where the front, back and garage doors should share a key, or a small business where every key-holder is trusted with every door. It is also common for padlocks on gates, containers and storerooms.
A master key system suits offices, warehouses, schools, complexes and multi-tenant buildings — anywhere staff, tenants or contractors should reach only their own areas while a manager can open everything.
A common request is for a large number of locks — say 40 across a site — to work on one common key. That can be done as a keyed-alike job. But if you might later want to limit some people to some doors, say so before the work is quoted: it is far cheaper to plan a master key system from the start than to convert one later.
How a master key system is planned
1. Survey the doors
A locksmith visits the site and records every lock: type, cylinder size, door and frame condition, and whether the lock can be master-keyed.
2. Decide who opens what
List the people or roles (owner, manager, staff, cleaners, contractors) and the doors each one needs. Keep it as simple as the site allows.
3. Draw up the key schedule
The locksmith turns that into a hierarchy — which doors share a change key, which master keys exist and who holds them.
4. Choose the cylinders and key profile
Decide whether keys may be copied anywhere or must use a restricted profile, and pick cylinders that fit the doors.
5. Quote, then fit
You get a written quote based on the schedule. Work is often done in phases so the building stays secure.
6. Keep a key register
Record who has which key and collect keys when people leave. A master key system is only as secure as its key control.
Can your existing locks be used?
Many South African buildings have a mix of lock types that have been added over the years. Pin-tumbler cylinder locks — including the euro-profile cylinders common on modern doors — can often be re-pinned or have just the cylinder swapped.
Older lever-type mortice locks are also common. They generally cannot be master-keyed in a practical way, and are usually replaced with cylinder locks as part of the project. Locks on security gates may use proprietary parts that only the gate manufacturer or an authorised installer can supply.
That is why a survey comes first: the number of locks that can be reused has the biggest effect on the price.
Keeping a master key system secure
- Keep the hierarchy as simple as the building allows — fewer levels, fewer master keys.
- Issue master keys to as few people as possible.
- Consider a restricted key profile so keys cannot be copied at a key-cutting kiosk.
- Keep a signed key register and collect keys when people leave.
- Agree in writing who holds the key codes and the key schedule, and who may order extra keys.
Frequently asked questions
What is the difference between a master key system and keyed-alike locks?
With keyed-alike locks, one key opens every lock and everyone with a key can open every door. With a master key system, each lock (or group of locks) has its own change key, and a master key opens all of them. Choose keyed alike when everyone should have the same access; choose a master key system when some people should only open certain doors.
Can my existing locks be master-keyed?
Sometimes. Pin-tumbler cylinder locks can often be re-pinned or have their cylinders swapped. Many older lever-type mortice locks cannot be master-keyed in a practical way and need to be replaced with cylinder locks. A site survey is the only reliable way to tell.
We need about 40 locks to work on one common key. Is that a master key system?
Not necessarily. If everyone who holds a key should open every lock, that is a keyed-alike job, which is simpler. If you also need individual keys that only open certain doors, it becomes a master key system. Either way, a locksmith will usually want to inspect the site before quoting, because lock types across 40 doors are rarely all the same.
Is a master key system less secure?
Each master-keyed cylinder accepts more than one key, and a lost master key can expose every door it opens. That risk is managed with a simple hierarchy, a restricted key profile, and a key register — not by avoiding master keying altogether.
What happens if a master key is lost?
Every lock that key opens is affected. Depending on the system, the locksmith may need to rekey or replace those cylinders. This is why master keys should be issued to as few people as possible.
How much does a master key system cost?
It depends on the number of doors, whether existing cylinders can be reused, the cylinder brand and grade, whether keys use a restricted profile, and how many levels the system has. A locksmith can only give a reliable price after surveying the site. Locksmiths on Vula24 set their own prices.
Can Vula24 arrange a master key system?
Vula24 is a marketplace and does not employ locksmiths. Send us your project details on WhatsApp or by email, and we will try to connect you with an independent locksmith in Gauteng or the Western Cape who designs and fits these systems. The locksmith inspects the site and gives you a quote. We cannot guarantee availability for every project.
Related
Planning a master key or keyed-alike project?
Vula24 is a marketplace and does not employ locksmiths. Send us the area, the type of site and roughly how many locks, and we will try to connect you with an independent locksmith in Gauteng or the Western Cape who can survey the site and quote.