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Identifying Locks – lever locks

The traditional type of lock normally fitted to wooden front door.  They come in two main categories:-


Deadlocks do not have handles, just an escutcheon. Sash locks are designed to be fitted with a pair of lever handles, which operate the latchbolt.

Commonly available in 2 finishes:

satin chrome and polished brass



Case dimensions

As you can see, there are many dimensions to check if replacing a lock!  It is always simpler to find a lock of the same type to avoid disappointment. Even if you get the same type of lock, there is normally at least 2 back-sets available – this is the measurement from the edge of the door to the centre of the keyhole as illustrated – 45mm and 57mm are most common.


Levers range from 2  and 3 lever (these are for internal doors or perimeter secondary security) to 5 lever and 5 lever B.S. (British Standard 3621) just to confuse , there have been a few British Standards – B.S.3621 1980 through to B.S.3621 2007 the latest being best. If the lock is a B.S. lock then it must display a ‘kite mark’

Nearly always, most of the information will be stamped on the cover plate on the forend of the lock

Below we can see this fore end is a 5 lever B.S. 3621:2007 made by Union.