3 Lever Deadlocksģ lever deadlocks are for internal wooden doors. When choosing your 5 lever lock, make sure it has the British Standard BS362 kitemark. This makes it more difficult to copy keys or break into. Required by insurance companies, a 5 lever deadlock is suitable for an exterior door and provides security in the form of additional 'levers' inside the lock. These deadlocks are commonly fitted in wooden front or back doors. A standard deadlock has 3 inch case with a backset (distance from the edge of the door to the centre of the keyhole) of 57mm. When choosing the right deadlock you will also need to make sure you choose the right size for your door. These types of locks are available as either 3 or 5 lever. A deadlock is a lock bolt only and does not have a latch/catch section for the operation of a door knob/handle. Read on to discover what a deadlock is and if you need one!Ī mortice deadlock is designed to be fitted into the timber edge of a door and allows the door to be manually locked from both sides with a key. It can, however, be confusing to know which type of mortice lock you need. What is the difference between a deadlock, deadbolt and sash lock? If you are fitting a new internal door in your home, and want to have a lock, you will need to choose one of these.