What is a Mortice Lock?

A mortice lock is a lock that is fitted in to a hole or pocket of a door, the word mortice refers to the hole in the door in which the lock is fitted. These types of locks are most commonly found on wooden doors and are more popular in the UK and Europe. A mortice lock is often refered to as a ‘Chubb’ type lock by people in the UK, since Chubb has become the brand leader for this type of lock during the last few decades.

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5 lever mortice lock in action

a mortice lock

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Mortice locks can be deadlocks or sashlocks (sashlocks incorporate a handle and latch mechanism, normally found on back doors) and can be devided in to 2 categories:

Lever Mortice Locks
Cylinder Mortice Locks

Lever Mortice Locks

These locks are the most common type of mortice locks fitted to domestic properties in the UK, the majority of lever mortice locks are very similar in their workings. A key is inserted in to the lock which when turned will lift levers to the correct height enabling the bolt to be locked and unlocked. Please see diagram.

Lever Mortice Lock Diagram

Lever Mortice locks can have a different number of levers depending on the application and thickness of doors, generally the more levers that are stacked in the lock case the thicker the lock becomes. More levers means more key differs, so it is less likely that another key will open more than one lock. A lock fitted with 5 levers is also more secure than a lock say fitted with 2 levers. The most common lever locks are:

2 lever mortice locks – This is a lock comprising of 2 levers, the lock case is thin, so it is suitable for installation in to interior doors less than 45mm thick, where a low level of security is needed. Not recommended for security on external doors.
2 lever mortice dead lock
3 lever mortice locks– More secure than 2 lever mortice lock and more widely used, with more manufacturers to choose from. Also suitable for interior doors less than 45mm thick. Not recommended for security on external doors.
3 lever mortice dead lock
5 lever mortice locks– Lock cases vary in size and can be used on thinner internal doors and external doors where a medium level of security is needed. Most locks come with a box strike.
5 lever mortice dead lock
5 lever British Standard (BS 3621) mortice locks– All the same features as a 5 lever lock with the addition of anti drill plates either side of the lock case and a larger reinforced dead bolt. Recommended for compatible internal doors (minimum of 45mm thick) and external doors where a high level of security is needed. Box strike comes as standard.
5 lever british standard (bs 3621) dead lock

A good way of checking to see if you currently have a British Standard lock fitted, as most insurance companies in the UK now stipulate that any final exit doors are fitted with at least 1 BS3621 lock, is to check for the British Standard kite mark. Which will be stamped on the faceplate of the lock on the edge of the door, as shown below.

bs3621-2007

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bs3621 dead lock

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Cylinder Mortice Locks

These locks are different to lever locks as a cylinder is used to throw the bolt rather than inserting a key in to the lock. They are more commonly found on commercial premises, although increasingly more people are now having them fitted to their homes as they offer more flexibility with master suites and restricted keys. Cylinder mortice locks are normally fitted with a euro profile cylinder or an oval profile cylinder, which can be key operated from both sides of the door or can be key operated from one side of the door and locked and unlocked with a thumb turn from the other side.