What is the difference between construction keying, master keying and keyed alike?

What is the difference between construction keying, master keying and keyed alike?

Keying systems play a vital role in managing access to different areas within a building - especially when it comes to commercial sites where various tradespeople are coming and going throughout different stages of construction.

You may have heard the terms “construction keying”, “master keying”, and “keyed alike” - these systems are used to provide specific access privileges and convenience. If you’re unsure of the differences between the three, here’s an explanation of each system and when you may want to use them.

Construction Keying

Construction keying is a temporary keying system used during the construction phase of a building. It allows builders, electricians, plumbers etc to access different areas of the site without having permanent keys. Once construction is completed, the system can be easily reconfigured to provide secure access only to the building's occupants.

How it Works

There are two main ways this is usually done:

Cylinder swap-out

A temporary construction core or cylinder is installed in the lock. Construction keys are distributed to contractors and workers, providing them access during the construction period. After construction, the temporary core is replaced with the permanent one, rendering the construction keys useless. The building owners or occupants then use their permanent keys, and construction workers no longer have access.

Temporary construction key

A specially keyed cylinder is used in the lock. This cylinder can operate on two keys. The first is a construction key that is distributed to contractors and workers, providing them access during the construction period. After construction, a “void” key is used - as soon as this enters the cylinder, it will alter the configuration of the pins, and the construction key will no longer work

Advantages of construction keying:

  • Security during construction - limits access to authorised personnel only
  • Easy transition: simplifies the changeover from construction to permanent occupancy
  • Cost effective: Reduces the need for multiple rekeying processes during construction

Master Keying

Master keying is a system where multiple keys can open one or more locks, but with varying levels of access. It allows a hierarchical control of access, enabling different groups or individuals to access specific areas while still providing complete access via a master key.

How it Works

This method sounds simple, but can become more complex with each level of required access. Traditionally the configuration of the lock pinning was worked out by hand on paper, but today there are software programs that make the process much easier.

  1. Hierarchical Levels: Different levels of keys are created, each with its own access privileges
  2. Grand Master Key: Opens all locks in multiple groups
  3. Master Key: Opens all locks within a particular group
  4. Maison Key: Common in apartment buildings or offices, these will operate communal and service areas, but not other individual areas
  5. Restricted profiles. Most master keyed systems will use a restricted key profile (you can tell these by the “do not copy” often stamped on them) that is registered with the locksmith who created the system. This prevents restricted keys from being copied at the local hardware store for example.


  • Access Control: Provides a structured access hierarchy, allowing specific access permissions
  • Convenience: Reduces the number of keys needed by facility managers and security personnel
  • Flexibility: Easily accommodates organisational changes and expansions

Keyed Alike

Keyed alike is a simple system where multiple locks are configured to be opened by the same key. This is commonly used for convenience in residential settings or small businesses where multiple doors or locks need to be accessed by the same individuals.

How it Works

  • Single Key: All locks in the system are keyed to be operated by a single key
  • Unified Access: One key provides access to all designated locks, simplifying key management


  • Convenience: Simplifies access by using a single key for multiple locks
  • Cost-Effective: Reduces the number of keys needed and simplifies key management
  • Ease of Use: Ideal for small businesses and residential settings where multiple locks need to be accessed frequently by the same individuals


Understanding the differences between construction keying, master keying, and keyed alike systems is important when choosing the right access control method for your building or property. Each system has its unique benefits and is designed to meet specific security and access needs.

By selecting the appropriate keying system, you can enhance security, improve access control, and simplify key management for your property.

Hardware Box entrance sets can be purchased as keyed alike, or keyed to differ.