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DOOR HARDWARE - Doorsets - Function & Backset

QUESTION: How do I determine which function I need for my door set?
ANSWER: There a 4 basic functions for conversion/tubular doorsets. These are passage, privacy, single dummy and double dummy. With passage and privacy sets there is also a backset choice of either 2 3/8" or 2 3/4".

Passage is the most commonly used and has knobs/levers that turn and operate a latch but there is no lock.
Privacy is like passage but there is a locking feature for bathrooms or bedrooms.
Single dummy is a surface mounted knob and plate for one side of a door with no functioning latch. Typically this is used for closet/pantry doors and ball or roller catches are used.
Double dummy is like single dummy but has trim for both sides of one door.

The diagrams below explain these functions in more detail.

Door Set Functions
Function Description Includes
Single Dummy
Single Dummy
No latch or lock - Like a cabinet knob, the knob or lever mounts on one side of the door and doesn't turn or operate a latch. Typically found on closet or pantry doors. This set can't be installed on a pre-drilled door.
  • 1 Knob or Lever
  • 1 Backplate or Rosette
  • Matching screws
  • All necessary mounting accessories
Double Dummy
Double Dummy
No latch or lock - the knobs or levers on this doorset don't turn or operate a latch. Typically found on closet doors or the passive door in a set of double doors. This set can't be installed on a pre-drilled door.
  • 2 Knobs or Levers
  • 2 Backplates or Rosettes
  • Matching Screws
  • All necessary mounting accessories
Passage
Passage Function
Latch but no lock - The knobs or levers turn and operate a latch but there is no locking ability. Typically found on interior doors that don't need to lock, or doors with a separate deadbolt.
  • 2 Knobs or Levers
  • 2 Backplates or Rosettes
  • 1 Passage Latch with matching face plate
  • 1 Matching strike plate
  • Matching screws
  • All necessary mounting accessories
Privacy
Privacy Function
Latch and lock - This set has a privacy pin next to the inside knob or lever which is pushed in to lock. The door is unlocked by turning the knob or lever on the inside and can also be unlocked from the outside by pushing a small screwdriver through the emergency release hole. Typically found on bedroom or bathroom doors.
  • 2 Knobs or Levers
  • 2 Backplates or Rosettes
  • 1 Privacy Latch with matching face plate and privacy pin
  • 1 Matching strike plate
  • Matching screws
  • All necessary mounting accessories


The backset is the horizontal measurement from the edge of the door to the center of the hole bored through the door. On a lock or latch this is the distance from the front of the face plate to the center of the door knob hub. The backset of the lock or latch needs to match the backset of the pre drilled hole in order to install the hardware without modifying the door. Tubular latches for conversion doorsets are usually 2 3/8" or 2 3/4" backset. See the diagram below for more detail.

Pre-drilled door prep for tubular latch installation
Tubular Backset Diagram