Deadbolts and deadlatches are both locking mechanisms commonly used in door security, but they operate differently and serve slightly different security needs. Here’s a breakdown of the key differences between the two:

Mechanism

• Deadbolt: A deadbolt is a locking mechanism that moves a solid metal bolt from the door into the door frame. The bolt movement is manually controlled by a key or a thumbturn from the inside.
• Deadlatch: A deadlatch, also known as a spring bolt lock, uses a spring to extend the bolt, which is then retracted by turning the doorknob or key. When the door is closed, the bolt automatically extends into the strike plate, locking the door.

Security

• Deadbolt: Deadbolts are highly secure because the bolt is moved directly by the user and cannot be easily forced back without a key or significant physical force. The lack of a spring mechanism makes it resistant to lock picking and bumping.
• Deadlatch: Deadlatches offer convenience and moderate security. They can be easily opened from the inside with a doorknob and from the outside with a key. However, they are generally considered less secure than deadbolts because the spring mechanism can be more vulnerable to certain attacks.

Types

• Deadbolt: There are two main types of deadbolts—single cylinder (which requires a key on one side and a thumbturn on the inside) and double cylinder (which requires a key on both sides).
• Deadlatch: Deadlatches may come with features such as an anti-carding feature that prevents the bolt from being pushed back easily.

Use Case

• Deadbolt: Ideal for external doors where high security is needed. The double cylinder deadbolt is particularly useful in doors with glass panels or nearby windows, as it prevents an intruder from opening the door by breaking the glass and reaching in to turn the thumbturn.
• Deadlatch: This type is best suited for internal or external doors where convenience is prioritized over high-level security. It is commonly used in residential entry doors with a deadbolt for added security.

Differences between deadbolt and deadlatch on a mortise lock

Installation and Compatibility

• Deadbolt: Installation of a deadbolt might require drilling a new hole in the door and door frame, especially if one wasn’t present before. This is because deadbolts need a larger hole for the bolt and a secure fit into the door frame for effectiveness. Deadbolts are versatile but may not fit all door types without modification.
• Deadlatch: Deadlatches often replace standard doorknob locks without needing significant additional modifications to the door. They fit into the same type of hole as a doorknob, making them an easy upgrade for many doors. However, ensuring the latch and strike plate are aligned is crucial for security and proper function.

Auto-Locking Feature

• Deadbolt: This feature does not automatically lock when the door is closed. The user must manually engage the bolt, either by key or thumbturn. This feature provides an added layer of security but can be seen as less convenient by some users.
• Deadlatch: Thanks to the spring mechanism, the door automatically locks upon closing. This feature is convenient for users who might forget to lock the door but also poses a risk of accidental lockouts.

Resistance to Physical Attacks

• Deadbolt: Offers high resistance to physical attacks such as kicking, ramming, or shoulder slamming. The strength of a deadbolt lies in the depth the bolt extends into the door frame (usually at least one inch) and the hardness of the bolt itself.
• Deadlatch: While offering moderate resistance to physical attacks, deadlatches are generally less robust than deadbolts. The automatic locking mechanism can sometimes be bypassed with enough force or specific techniques, especially if not installed correctly or if the door frame is weak.

Key Control and Smart Features

• Deadbolt: Modern deadbolts come in versions that offer key control (preventing unauthorized duplication) and smart features, including remote locking/unlocking, access logs, and integration with home security systems. These features enhance both security and convenience but come at a higher cost.
• Deadlatch: Some deadlatches also come with smart features and improved key control. However, the focus with deadlatches remains on convenience and moderate security. Smart deadlatches are less common and may offer fewer features than smart deadbolts.