What kind of lock does a sliding glass door have?

Most made since the 1980s have a mortise hook lock: a lock body inside the panel edge behind a rectangular face plate, with a hook that swings into a keeper on the jamb, operated by the handle set. Older aluminum doors often have a surface-mounted latch built into the handle.

What is the screw spacing on a sliding door handle?

The centre-to-centre distance between the two screws holding the handle on. 3-15/16 in is the most common, then 4-15/16 in; 5-3/8 and 6-9/16 in are seen on older and wood doors. It is the single most useful measurement.

My sliding door lock won't catch. Do I need a new lock?

Often not. The usual reason is that the panel has sagged on worn rollers so the hook no longer meets the keeper. Check the roller height first; if the panel is square and the hook still misses, or the handle turns without moving the hook, the lock is replaced.

Can I get a sliding door lock with a key?

Yes. Keyed handle sets and separate keyed locks exist for most doors, and a keyed set can usually be keyed to match the house afterwards.

Sliding Door Lock Identifier — Mortise, Surface, Hook or Latch

How this works

Sliding door locks come in two families: a mortise lock inside the edge of the panel, operated through a handle set, or a surface lock built into the handle itself. Within each, the parts are matched by screw spacing, face-plate size, hook direction and the door's hand — not by the brand of the door.

The measurements listed at the end are the ones a technician or a parts counter needs. Screw spacing is the first, and a clear photo of the panel edge with the lock turned is the second.

It runs in your browser and nothing you enter is sent anywhere. It is a guide, not a diagnosis — door makers differ, so check your manufacturer where it says to, and the technician confirms what has actually worn when they see the door.

Questions people ask

What kind of lock does a sliding glass door have?: Most made since the 1980s have a mortise hook lock: a lock body inside the panel edge behind a rectangular face plate, with a hook that swings into a keeper on the jamb, operated by the handle set. Older aluminum doors often have a surface-mounted latch built into the handle.
What is the screw spacing on a sliding door handle?: The centre-to-centre distance between the two screws holding the handle on. 3-15/16 in is the most common, then 4-15/16 in; 5-3/8 and 6-9/16 in are seen on older and wood doors. It is the single most useful measurement.
My sliding door lock won't catch. Do I need a new lock?: Often not. The usual reason is that the panel has sagged on worn rollers so the hook no longer meets the keeper. Check the roller height first; if the panel is square and the hook still misses, or the handle turns without moving the hook, the lock is replaced.
Can I get a sliding door lock with a key?: Yes. Keyed handle sets and separate keyed locks exist for most doors, and a keyed set can usually be keyed to match the house afterwards.

What kind of lock does my sliding door have?

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Questions people ask

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