Australian deadlatch and deadlock
A surface deadlatch with a key outside and a knob or slide inside, plus a separate deadlock on many doors. Mechanically close to the UK nightlatch but with its own case geometry and a strong local brand ecosystem.
Also called: Deadlatch · Lockwood-type latch · Night latch (AU)
Anatomy
- Surface case with a spring deadlatch
- Rim cylinder through the door face
- Inside knob, slide or snib
- Optional separate deadlock below
Parameters to measure
Measure in this order: Lock case width × height × depth → Backset (Dornmaß) → Door thickness
| Parameter | Typical values | Tolerance that still fits | How to measure |
|---|---|---|---|
| Lock case width × height × depth | Survey locally — cases vary widely | — | Width and height of the surface case. |
| Backset (Dornmaß) | 60 mm common | — | Door edge to the cylinder centre. |
| Door thickness | 35–45 mm | — | At the cylinder. |
Retrofit architectures that work
- Motor on a rim (surface-mounted) lock — A motor unit is fixed to the surface-mounted rim lock case or to its knob, driving the latch or the deadbolt. Common on UK nightlatches and on Asian surface-mounted deadlocks.
- Surface motor on a deadbolt turn-piece — An adhesive or screw-fixed motor sits on the door face and rotates the existing deadbolt turn-piece. Nothing is drilled. This is the standard approach for North American single-cylinder deadbolts and for many Asian rim deadbolts.
- Motor replacing the interior handle — The interior lever or knob is replaced by a motor unit that drives the 8 mm spindle directly. The outside keeps the original key cylinder and handle. This is the cleanest fit for mortise locks where the bolt is thrown by the key and the handle only retracts the latch.
The inside control is often a slide or a snib rather than a rotatable knob, which no clamp adapter handles. Design an adapter that pulls, not just one that turns.
Related standards
AS 4174 (designation to be confirmed)
Reference devices
Recorded as engineering examples, not endorsements.
- Push-pull digital lock sets (Asian market category) — Full lock replacement on the same footprint ⚠ needs review
Questions
Is a deadlatch secure on its own?
A deadlocked deadlatch resists slipping, but most Australian insurers still expect a keyed deadlock on an external timber door.