Glass Sliding Door

Sliding leaves cannot use a bolt that throws straight out, because there is nothing in line to throw into. They use a hook bolt that rotates into a keep on the fixed jamb. That mechanism, plus a typically narrow sliding stile, defines what can be fitted here.

Why sliding doors are different

Hook bolt, not deadbolt - the bolt rotates and hooks behind a keep, resisting the door being lifted or slid open.
Narrow stile - sliding leaves usually run a slim stile, so the mortice case has to be correspondingly narrow.
Reduced backset - commonly 25 mm to 35 mm rather than the residential 60 mm.
Two-leaf geometry - the keep sits on the fixed panel or jamb, and its position has to align with the bolt through the full slide.
Track condition - worn rollers drop the leaf and pull the hook out of alignment with the keep.

Measure before ordering

Measurement	Where taken	Why it matters
Stile width	Face of the vertical member on the sliding leaf	Determines whether the mortice case fits
Backset	Leaf edge to cylinder or spindle centre	Sliding formats use reduced backsets
Case depth	Cavity inside the stile	Limits the mortice body that can be inserted
Keep position	Fixed jamb or adjacent panel	The bolt and keep must align at the closed position
Leaf drop	Gap at top and bottom, open and closed	Indicates roller wear that will cause misalignment

Fix worn rollers before fitting a lock. A leaf that has dropped even a few millimetres will make a correctly installed hook bolt feel stiff or fail to engage, and it is invariably blamed on the lock.

Also covers

Sliding security screens running alongside a glass slider
Stacker and multi-panel sliding systems
Patio and courtyard sliders on aluminium frames

Related categories

Hinged Security Screens · Door with Narrow Frame · Frameless Glass Doors · Mortice Locks

Common questions

Can I fit a standard smart deadbolt to a sliding door?
No. A straight-throwing deadbolt has nothing to enter on a sliding leaf. Sliding doors need a hook bolt mortice designed for the format.

What backset do sliding doors use?
Typically 25 mm to 35 mm, considerably less than the 60 mm common on residential hinged doors. Measure the existing hole rather than assuming. Measuring backset.

My sliding door is hard to lock now. Is the lock failing?
More often the rollers are. As they wear, the leaf drops and the hook no longer aligns with the keep. Check the gap at the head of the door open versus closed before replacing the lock.

Guides and reference

Ch 04 - Door type compatibility · Ch 02 - Stile width · Hook and swing bolt throw