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How Do Bank Vault Doors Work - 5 Surprising Things About Security Doors

By Maria Paiz October 23, 2023

How do bank vault doors work? Cover

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Bank vaults are highly secure structures built to secure valuables like cash, jewels, confidential documentation, and other irreplaceable goods. Vault Manufacturers use solid materials for vault construction to withstand severe impacts. Bank vaults are secured by concrete vault doors, offering security against theft attempts and disasters.

A typical bank vault door has a full-length lock bar, two steel-clad UL-listed combination locks, a built-in micro-switch, and an emergency ventilator. This read will help you understand how a bank vault door works and some additional interesting factors.


How Do Bank Vault Doors Work?

Manufacturers work closely with banks to create advanced vault doors. They make sure the door fits the bank's needs, like size and location. This happens before the bank building is put up.

Vault doors are mainly made from solid concrete with steel inside. The thickness of the door makes it even tougher. Most older vaults had doors 18 inches thick, making them hard to break or change. However, modern-day manufacturers use special concrete and additives to make doors just 3 inches thick but way stronger.

Vault doors are different from vaults. They have modern locks covered in stainless steel for smooth operation. Banks usually use a special lock that only opens after a set number of hours. Moreover, it needs two people to open it for added security. This lock is also connected to a time lock. So, if you want to unlock it, you'll have to wait until the pre-set number of hours passes. 

How Much Does a Vault Door Weigh?

Vault doors are renowned for their steel-reinforced structure, designed to offer maximum security. After crafting these doors, manufacturers subject them to rigorous testing, including the UL Class 1, 2, and 3 tests, to ensure their strength and quality, especially for bank vaults.

The stainless-steel finish, combined with the door's large size, contributes to its significant weight. However, despite their robust nature, these doors are designed to allow average-height individuals to enter and exit the vault comfortably.

Vault Door Specifications by Class:

  • Class 1 Vault Door:

    • Dimensions: 36” wide x 78” high
    • Overall Thickness: 9 1/16”
    • Swing Radius: 41 ⅞”
    • Weight: 2910 lbs.

  • Class 2 Vault Door:

    • Dimensions: 36” wide x 78” high
    • Overall Thickness: 10 ½”
    • Swing Radius: 41 ⅞”
    • Weight: 3456 lbs.

  • Class 3 Vault Door:

    • Dimensions: 36” wide x 78” high
    • Overall Thickness: 12 ½”
    • Swing Radius: 41 ⅞”
    • Weight: 4340 lbs.

It's worth noting that while these are standard specifications, vault doors can come in custom sizes and lock combinations to suit specific requirements.


How Much Does a Bank Vault Door Cost?

Bank vault doors are a potential investment that pays off in the long run. If you buy a custom bank vault door, you may need to care for the additional costs of designing the door. The prices may also depend on building a complete bank vault or buying a door. Vault manufacturers can offer you a quotation for vault construction.

You can find customized door options for $9,000 to $20,000 when buying a new vault door. The cost can vary based on the size and shape.


Why Are Bank Vault Doors Round?


Banks usually have round vault doors. Here’s the science behind it. Round vault doors are uniformly fit into the hole, leaving no space for stress concentration. Rectangular doors have a higher risk of stress concentration around the corners (based on their construction). Moreover, round vault doors can be accurately carved and placed into the opening, minimizing the possibility of gaps and errors.

Manufacturers can fit the round doors by pushing big rods into the maintenance hole covers. It avoids the possibility of distortion in long-term use. Furthermore, bank vaults use a dual-control combination lock. They do not require a jacking force to push them in place.

While true, this does not mean rectangular vault doors are a bad alternative. Such doors can be an ideal fit for home vaults. They can thoroughly protect your valuables without bearing the risk of breach.

How Thick Is a Bank Vault Door?

The thickness of the vault doors varies based on the type and year of manufacture. If we look back at some of the historical vault storages, we may find them very thick. It is due to the lack of technology back in the day. Manufacturers solely relied on building thick concrete structures for security measures. Gauges can determine the thickness of steel. The lower the gauge, the thicker the steel, and vice versa.

Modern-day bank vaults have a thickness (of steel) ranging between 6-gauge (¼ inch) to 4-gauge (⅜ inch), with 4-gauge being the thickest. For your ease, we have mentioned the standard thickness options for bank vault doors below.

  • 7-Gauge (¼ inch)
  • 6-Gauge (5/16 inch)
  • 4-Gauge (⅜ inch)
  • 2-Gauge (½ inch)

How Can I Determine the Effectiveness of a Bank Vault?

The effectiveness of bank vaults may be hard for an ordinary person to determine. While true, there are a few factors that you can consider.

Locking Mechanisms

Check if the vault uses a Group 2 or Group 1 combination lock. Group 1 locks are considered more secure based on their complexity and resistance to manipulation. You may also look for additional security features like re-locking mechanisms. Such features come into action when tempering is detected, creating an extra barrier to unauthorized access. Some vaults may be equipped with time-delay locks, causing a delay between entering the correct combination and the door opening.

Vault Structures

Check the steel’s thickness using gauge measurements to determine its effectiveness. For instance, a 4-gauge (3-inch) thick steel provides a higher resistance to forced entry than a 7-gauge (¼-inch) thick steel.

Manufacturer’s Reputation

Manufacturing methods play a crucial role in a vault’s effectiveness. Advanced techniques like Tungsten Inert Gas (TIG) welding ensures high structural integrity. Moreover, a manufacturer's compliance with certifications like UL 608 may indicate its competency in the market.

Underwriters Laboratories (UL) Tests

Bank vaults with UL test ratings, like TL-15 (Class 1), TL-30 (Class 2), or TRTL-30 (Class 3), can be highly effective. TL-15 indicates a vault that can successfully withstand a rigorous 15-minute attack. TL-30 means a vault that can withstand a determined attack for 30 minutes. Lastly, TRTL-30 indicates a vault that can withstand a relentless 30-minute attack while resisting explosive attacks.

ul certification on bank vault doors


FAQ Guide (What Readers Want to Know)

What is a bank vault door made of?

Bank vault doors use steel-reinforced concrete blended with proprietary additives. The composite structure provides the vault with an unparalleled toughness to withstand any level of theft attempts.


Can you open a bank vault from the inside?

Some bank vault doors can be opened from the inside using a release lever (present on the inner side of the vault door). While some vaults allow this method, opening the vault from the inside without authorized access (or without informing the bank’s management) may trip the alarm and summon the police.


Can you buy a bank vault door?

If you are building your bank, you can buy vault doors for your storage from vault manufacturers. Custom bank vault doors may cost from $9,000 to $20,000 or more.


How strong is a bank vault door?

A typical bank vault door can be 3.5 ft. thick with tons of weight. The door's steel rods and concrete formation make it among the most challenging doors to break into.

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