Ever wonder why door hardware is so complicated?
 Doors are a moving part. Moving parts tend to be a royal pain whether they be on a machine, a vehicle, or a building . Quite often doors are the only moving part of a structure.
 Doors are used by people. As such, doors must not only meet building code requirements but also have to meet the wide variety of needs of the people that use them. Some people are tall, some are short. Some are fast, some are slow. Some are even handicapped.
Doors (and hardware) have to adapt to all these needs.
Not only are doors the only moving part within a building, but that moving part has to also adapt to an ever changing variety of needs.
Fire rated doors require fire rated hardware.
The top hinge on a door receives the most stress.
A standard commercial door is 1-3/4” thick and uses a lock with a 2-3/4” backset.