Mortice Lock vs. Night Latch: Securing Your Wooden Doors to BS 3621

For traditional wooden or timber doors, security involves layering different types of locks. The two most common mechanical lock types are the Mortice Lock (Deadlock) and the Night Latch (Rim Lock). Understanding the difference—and ensuring your locks meet British Standard (BS 3621)—is essential for securing your home and validating your contents insurance.

The Mortice Deadlock (The Primary Security)

The mortice deadlock is housed within the door itself (morticed) and provides the strongest physical security against forcing or manipulation.

• Function: It requires a key to lock and unlock from both sides (or a key on one side and a thumb-turn on the other).

• Security Standard: For external wooden doors, the lock must be a 5-lever mortice deadlock and be Kitemarked to BS 3621. This certification guarantees the lock has been tested against drilling, picking, and sawing.

• Insurance Requirement: Most UK home insurance policies mandate a BS 3621-compliant lock on final exit doors.

  
  

The Night Latch (The Convenience Lock)

The night latch is a secondary lock that is surface-mounted onto the inside of the door.

• Function: It is self-locking when the door is pulled or slammed shut, offering immediate convenience when you leave the house.

• Security Standard: While convenient, a standard night latch provides poor security against entry techniques like slipping the bolt. For insurance compliance, it should be paired with a BS 3621 deadlock or upgraded to a BS 3621-compliant automatic deadlatch.

  
  

The Right Combination for Maximum Security

The optimal security setup for a wooden door is layering:

• Primary Security: A BS 3621-compliant 5-lever mortice deadlock (for when you leave the house or go to bed).

• Secondary Security: A strong automatic night latch (for quick exits and daytime use).

Local Authority Check: Ensure you choose quality brands like Yale, Union ASSA Abloy, or Chubb—we supply and fit all of these high-quality, British Standard locks across Poole and Christchurch.

Is your home secured to BS 3621 standards? We offer free security assessments and installation of Kitemarked locks. The price we quote is the final, fixed price. No hidden fees or surprise out-of-hours charges. Call Peter directly on: 07304 073538.