Singapore HDB main-door mortise set and metal gate lock
A two-door entrance: a fire-rated timber main door with a mortise lock set, and a metal security gate with its own latch. Most Singaporean retrofits are full lock replacements sized to the existing mortise, and the constraint nobody expects is the clearance between the door handle and the gate handle.
Also called: HDB digital lock · Main door mortise · Gate lock
Anatomy
- Fire-rated timber leaf, commonly 42–50 mm thick
- Mortise lock case, often a 2-bolt or 3-bolt set
- Push-pull or lever handle set
- Metal gate with a separate latch, opening onto the corridor
Parameters to measure
Measure in this order: Door thickness → Backset (Dornmaß) → Centre distance, spindle-to-cylinder (Entfernung / PZ) → Clearance between door handle and gate handle → Fire rating of the door leaf
| Parameter | Typical values | Tolerance that still fits | How to measure |
|---|---|---|---|
| Backset (Dornmaß) | 60 mm typical on HDB timber doors; 55 and 70 mm occur | Match exactly or use an adjustable case | Door edge to the centre of the cylinder or keyhole. |
| Centre distance, spindle-to-cylinder (Entfernung / PZ) | 85 mm or 92 mm on many Asian mortise sets | None | Handle spindle centre to cylinder centre. |
| Door thickness | 40 mm minimum for most digital lock fittings; fire-rated leaves 42–50 mm | — | Measure the leaf at the lock. |
| Clearance between door handle and gate handle | Often only 20–35 mm between handles | Decides whether a deep handle is possible at all | Close the gate, then measure from the door handle to the gate handle. |
| Fire rating of the door leaf | 30 minutes, 60 minutes for units near lift lobbies or staircases | — | Check the label on the door leaf and the doorset certificate. |
Retrofit architectures that work
- Full lock replacement on the same footprint — The old lock case is removed and a smart lock with the same footprint takes its place. This is the dominant approach in East and Southeast Asia, where push-pull digital locks replace mortise sets on HDB, condo and apartment doors.
- 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.
- Gate actuator (lever, chain or magnetic) — Metal security gates get a dedicated actuator: a motor pulls a lever or a chain, or an electromagnet releases the gate latch. Very common in Singapore, Malaysia and Southern Europe where the gate is a second door.
Slim-profile locks exist specifically for the gate-clearance problem. On a fire-rated leaf the replacement must carry an SCDF-recognised Certificate of Conformity for the doorset — a lock certificate alone is not the same thing. The gate is usually automated separately.
Related standards
SCDF CoC (Singapore) · EN 12209 · EN 1634-1
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
Do I need HDB approval to fit a digital lock?
A routine lock replacement is treated as maintenance, but you must not compromise the door's fire certification and must not obstruct the escape route or the common corridor.
Why does my new handle hit the gate?
Because the new handle is deeper than the old one and the gate swings close to the door face. Measure the clearance before ordering and choose a slim profile.