Metal Door Locks Explained

March 16th, 2023

Written by Jeff Seymour

hooply metal door lock

Metal doors produced for residential houses have existed since the late 1970s. Many use different locks than a conventional wooden or uPVC door.

Everest, the door and window manufacturer, and Union locks made a door-locking system that you will see on many metal doors.

In this blog, I will explain in more detail about metal doors, how to lock them, the problems with the doors and the locking systems, and how to upgrade and make them more secure.

How do you Lock a Metal door?

How to lock a metal door depends on what type of metal door you have. So first, let's look at the most common metal door manufactured by Everest that uses a locking system called a Union Monarch. These have three locking points. When the system is fully locked, you can see them at the top, middle and bottom of the door edge. In addition, some of the later doors have shot bolts from the top and bottom of the door, adding extra security. These doors are very secure, even by today's standards for home security.

An excellent way to upgrade these is to have a more secure cylinder fitted, like a Yale 3 Star Euro cylinder or a Euro cylinder that is insurance approved and carries the British Kitemark.

Union still supplies metal door locks for the Monarch, which would need fitting by a professional locksmith to ensure the system works as it should.

Other metal door types lock similarly but mostly rely on a central deadlock that uses a cylinder and through a deadbolt from the door edge into the door frame. Spare parts for all metal door lock types can be sourced.

Union Monarch
Union Monarch

Can I screw into a Metal door?

Yes, metal or steel screws must be used, not wood screws. A small diameter hole must be drilled before using the screw, or you can use self-drilling metal screws to save having to use a drill first. Ensure they are the correct diameter for what you are fixing to the door.

Self-drilling metal screws
Self-drilling metal screws

Can I put a Bolt on a Metal Door?

Yes, the same principle as putting a door chain on the door. Make sure to use metal screws and not wooden screws.

Can I have a Nightlatch on a Metal Door?

Yes, you must use a professional Locksmith to install a nightlatch on a metal door. They will have the correct tools to fit a Nightlatch. A 32mm hole must be cut through the door to fit the cylinder.

Can I Have a Spyhole Glass on a Metal Door?

Yes, as long as the metal door has no glass panel.


Can I Install a Deadlock on a Metal Door?

Yes, this would need to be completed by a professional locksmith to ensure that the deadlock is fitted correctly and is the correct type for the door.

The deadlock would be a case that is operated by a cylinder. The cylinder can be a thumb-turn, making it easy to lock or unlock from the inside without using a key. These also can be British Standard meaning they are insurance approved.

It is not good practice to fit a Thumb Turn cylinder if small children are in the house. However, they can soon work out how to open the door because no keys are needed.

Can I Replace my Metal Door Lock?

Yes, a modern British Standard cylinder fitted will upgrade your door and provide better security. Using a British Standard cylinder would also make the door insurance approved.

How Do You Reinforce a Metal Door?

The easiest way to reinforce a metal door is to install bolts and use a professional Locksmith who will ensure they are fitted correctly and be the correct type.

What are Steel Security Doors?

Steel Security Doors are primarily found in commercial buildings and offer a very high level of security. The locks used in these types of doors are reinforced. When the key is turned, they use a system that shoots bolts from the door into a solid steel door frame. The key can then be turned again, deadlocking the steel door. They are known as Hoopley Locks. They use a separate cylinder that can be replaced without replacing the expensive Hooply lock system.

Hooply Lock
Hooply Lock

What are Metal-framed Glass Commercial Doors?

Metal-framed Glass Commercial doors are mostly fitted on shop fronts. They use lock cases that are known as Adams Rite gearbox cases. They come in a variety of sizes and different operations. In addition, the cylinders that operate the gearbox can be replaced rather than replacing the gearbox, making it much cheaper if you need a new lock.

Adams rite gearbox hook
Adams rite gearbox hook
Adams rite bolt with screw in cylinder
Adams rite bolt with screw in cylinder

By reading this blog, I hope you better understand how metal doors work and how to replace parts and make them more secure. If you need any advice on your metal door, please don't hesitate to call Jeff at Locksmith Direct.

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About the Author

Jeffrey Seymour

Jeffrey Seymour is a renowned locksmith known for his exceptional skills in the field of locksmithing and security. With over 10 years of experience in the industry, he has a passion for helping people secure their homes and businesses, and his knowledge and expertise in the latest security technologies and techniques have made him a sought-after expert in the industry. Jeffrey's attention to detail and commitment to providing high-quality service has earned him a reputation as one of the best locksmiths in the business. He continues to educate himself on the latest advancements in the field and is dedicated to providing his clients with the best possible service and protection.

March 16th, 2023

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