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Grand Master keys (GMK)

Privacy and security are two extremely important factors for smoothly running and managing a property.

When it comes to successful businesses, the owners must look for ways to efficiently run the premises and protect the business’s plans and resources. These include the property, the employees, and all the things inside the building.

One way to protect these things from vulnerabilities and security risks includes the implementation of a high-grade locking mechanism.

Good-quality locks ensure that what’s inside stays protected and no unauthorised individual has access to it. Locks come in pairs with keys, and while the former keeps your valuables protected, it is the keys that allow or restrict access.

Whoever has access to the keys has access to the lock and the things inside, and that makes key management crucial for a property’s security.

If you’ve ever had more than 10 doors to manage, you would know how stressful it can be to manage the keys and keep them safe. They are one of the most commonly lost and misplaced items and can put your entire property at risk.

Master keys are a great way to reduce the number of keys in a building with several access points and manage the access permissions of various individuals within an organisation.

Read on to find out more about master key systems, what grand master keys are, how they are used, their advantages and disadvantages, and much more:


Before we talk about grand master keys, you need to understand what a master key system is and how it works.

In simple words, a master key system is a security system that uses a multi-tiered framework to grant individuals different levels of access within an organisation.

It consists of the master keys, locks, users, and the complete hierarchy that makes up key management for master key holders.

While a single master key can grant high-level access to an individual user, it is the master key system that determines how securely the master keys are being used in the entire organisation and at different levels of master key access.


Keying levels are an integral part of master key systems and it is important to understand how they operate to understand the concept.

The 4 basic levels of a master key system include:

  1. Great grand master keys (GGMK)
  2. Grand master keys (GMK)
  3. Master keys (MK)
  4. Sub-master keys

Keying levels are similar to an organisational chart in a company. Therefore, when thinking of them, simply imagine a structured corporate organisation chart with different designations.

At the top of a basic chart is the CEO or Executive. Under them are the Department Heads or Supervisors, and under the Supervisors are the employees and other staff members.

The top level, i.e., the CEO or Executive block would be the Grand Master key level which would operate all locks within the property, including those at multiple facilities.

The Department Heads and Supervisors would represent the Master key level, which would be able to operate any lock on any door, only in their specific building or area.

For instance, master key 1 would be able to operate all the locks in building 1, master key 2 would open all the locks in building 2, and so. Master key 1 wouldn’t work on the locks in buildings 2 and 3, and vice versa.

The final level would be the employees and other staff members and they would denote the sub-master or change key level which would grant them access to only a specific area within the building.

For instance, someone who works in the research department would only be given access to areas approved by the relevant department. They won’t be allowed access to other people’s offices, the data room, and the financial department.

In summary, sub-master keys give access to only one lock, which a master key can also open. Master keys can lock and unlock all the change keys below them in the system.

Grand master keys give access to everything under them, and on top of that, the great grand master key grants access to all the grand master, master, and sub-master keys under it.


A great and effective way to access all the locks within a building is by using a grand master key. It is at the topmost level of the master key system and enables business owners and managers to access all areas of the building with ease.

A grand master key looks like any other key within a master key system. However, for it to work, the lock cylinders must have “master pins” in them that line up when the key is inserted.

A grand master key system uses a pin-and-tumbler design to unlock using different types of keys, which is made possible due to a series of small pins with varying lengths lining the slot where the key is placed.

The bottom pins inside the locks are located completely inside the plug and the upper pins are halfway in. Only the right key can move the pins into the correct position and unlock the doors.

For a master key, a third pin, also called a master wafer, is inserted inside the locks that separates some of the rows of the pins. This enhances the way that the locks are opened and only works with a master key.

A grand master key (GMK) is a master key system that uses three or more keying levels to control access to a property, or multiple properties.

When used on a single multi-level building, the grand master key is the top-tier key that opens all the locks on the property, unless specified otherwise.

A grand master key is different from a master key in terms of the keying level and the number of locks it can open within the system.

A grand master key system is an extensive keying system that requires the locks to be master keyed into certain groups. The master keys can operate all the locks within their own group, but not in other groups, whereas the grand master keys can open all the locks in all the groups.


Grand master keys are used to access multiple master key systems. They will open all the master key systems under it and the subsequent sub-master keys under them.

Depending on the design requirements and the overall size of the building (or multi-campus buildings), grand master key systems can range from simple to complex designs and can have varying levels of master keys.

They are generally used in places that require a more granular approach to security and are more commonly used in properties such as school systems and districts, hospitals, universities, offices, hotels, and residential flats.

For big properties like the ones mentioned above, it can be frustrating to have to manage a giant ring of keys for multiple doors and buildings. Not only is it extremely stressful but can cause serious security vulnerabilities if they get lost or misplaced.

A master key system is the solution for better key management and a great way to reduce the number of keys for your property while maintaining its security.

For example, if you are managing 10 commercial buildings, you can reduce the number of keys you, or anyone else requiring multi-access to the properties, would need to access them.

Reducing the number from say, 30 to 1 would ensure better control and management, while still granting access to the designated areas.

When designing a master key system for your property, you need to plan and customise for different areas, properties, and levels of access.

It is often the best practice, and the easiest, to follow the building’s organisational chart as we mentioned earlier in this article.


Implementing a grand master key system on your property can solve issues such as key management, control, safety, privacy, and security.

Without it, you may find it difficult to manage all the keys (which can be a lot depending on the size of the building and the number of users) and control access to each room in the building.

There are several benefits of grand master key systems that include:

Enhanced security

Having a grand master key system allows you to manage different levels of security and access to various individuals within the organisation.

This way, you won’t have to worry about employees, or other unauthorised individuals, making their way to areas in the building where they have no business going, such as where important and confidential documents are stored or where official meetings are being conducted.

Streamlined access

The best part about having a master key system is that it eliminates the need to carry around a heavy key ring with keys to different doors for single or multiple properties, depending on how many you have to manage.

Imagine having to go through it to open a door during an emergency and not being able to find the right key, which is very much plausible.

To avoid this issue of having to manage too many keys at once, a grand master key system gives you access to multiple facilities with just a single key.

Maximised control

Depending on your requirement and business decisions, you may either keep the master key only with yourself or duplicate it and hand it out to a trusted employee or board member.

As long as you have the original master key, you will have full authority over it and your permission will be required for duplicating it.


While there are several advantages of grand master key systems, the inability to manage them properly can bring forth a few of their vulnerabilities as well.

It is important to understand their potential drawbacks and pitfalls to make sure you take the necessary steps and precautions to avoid them and enjoy only the advantages that these convenient and efficient systems have to offer.

The main concern facing master key systems is the lost key dilemma. Losing a master key means that you will have to rekey or replace all the locks on the system to reduce the risk and vulnerability.

The higher the level of the lost master key, i.e., the grand master or great grand master key, the higher the security risk. Not only can this be unsafe and inconvenient but can also prove to be expensive.

It may be important to note here that while keyless entry systems have a higher upfront cost than traditional keys and master key systems, they are much safer since there are no keys to lose.

Another issue with master key systems is that of upgrading access and changing employees’ keys as they move up the designation ladder.

If you want to allow certain individuals access to a specific area on the property which was previously restricted to them, you will have to take the time out to physically swap the keys.


To make the most of your master key system and enjoy all its benefits while minimising the drawbacks, you need to focus on proper key management.

A few main factors to consider include:

Hardware keying design

This is the first step in effective master key system management and is directly related to the property’s structure.

It involves determining the various entry points requiring keyed locks and creating a security hierarchy corresponding to the access permissions within the organisation.

It requires you to determine which entry points will allow access to the general public and limited users or require high-security access control, which is something an experienced professional locksmith can help you with.

Access permission policies

This refers to the key holders and users within the system and requires you to outline who will require access through the various access points within the organisation.

Along with the access permissions, it is also necessary to assign access restrictions to the users since they determine the type of users that won’t be permitted to access high-security areas.

Key tracking

Key tracking allows the property owners to keep a record of all the keys’ access permissions along with the people responsible for them.

All keys must be stamped with unique serial numbers and assigned to a particular access level. This record-keeping allows you to keep track of who the keys are given to, who approved the access permissions, and the dates of issuance and return.

Key storage

Key storage refers to providing a secure place to keep the keys, their duplicates, as well as their backup copies.

There are different types of storage cabinets depending on the number of keys included in the system, all of which make it possible to locate the keys, identify if any are missing, and track who is responsible for each one.

Many property owners are now turning to electronic key management systems, which are cabinets made of steel and require a code or proximity access card to unlock them.

In addition to providing safe key storage, they also keep a digital record of key issuances and users and send automatic notifications when the keys are not returned on time.


Calder Security has been in the security industry since 1976 and we are members of the Master Locksmith Association (MLA).

We provide all kinds of security solutions designed bespoke to your property’s requirements and are experts in both master key systems as well as electronic and keyless access control systems.

Our expert team of SSAIB approved installers can help you assess your security needs and offer the right master key system or access control system including intercom, proximity fob, card swipe, keypad, and biometric systems that work with fingerprints or retina scans.

We are experienced in creating sophisticated access control systems for residential properties, large scale commercial enterprises, as well as smaller businesses.

We offer expert key cutting services from our Lock and Safe Shop in Wakefield where you can get your keys cut while you wait. We can cut virtually any key to a high degree of accuracy without having to send them away to be cut using our state-of-the-art digital equipment and key cutting machinery.

We can also work on a wide range of locking mechanisms, are specialists in wooden, UPVC, and aluminium doors, and are the official suppliers for leading lock brands including Chubb, Yale, Securikey, and Garrison.

Contact us here or call us on 0800 612 9799 to talk to our professional locksmiths right away!


Photo by Samantha Lam on Unsplash