Singapore HDB metal security gate lock

The second door of a Singaporean entrance, and the one that defeats most smart-lock products. It is a metal gate, not a door: bars instead of a leaf, no mortise pocket, exposure to weather, and a main door sitting only tens of millimetres behind it. Everything that works on a timber door has to be re-derived here.

✓ verified · Where you will meet this lock: Singapore, Malaysia

Also called: Gate lock · HDB gate digital lock · Grille lock

Anatomy

Vertical round or square bars, commonly around 100 mm apart on wrought-iron gates
A vertical stile carrying the latch — often hollow and unreinforced
A latch or hook engaging a frame-mounted strike
On retrofits, a welded 3 mm mild-steel lock plate behind the mechanism, because a lock cannot be mounted to a hollow bar

Parameters to measure

Measure in this order: Gate-to-door depth clearance → Gate leaf thickness → Backset (Dornmaß) → Gate bar spacing → Clearance between door handle and gate handle

Parameter	Typical values	Tolerance that still fits	How to measure
Gate leaf thickness	`22–40 mm; products on the market accept 22–28, 23–40 and 22–60 mm ranges`	Must fall inside the product's stated range	Measure the gate leaf at the stile where the lock will sit.
Backset (Dornmaß)	`40–45 mm on gate locks sold for HDB`	None	Gate edge to the centre of the cylinder or latch.
Gate-to-door depth clearance	`Standard gate locks need roughly 75–95 mm; under about 70 mm a standard body will strike the main door handle`	This decides whether a standard or a slim body is possible	Close both the gate and the main door, then measure from the back of the gate stile to the face of the timber door.
Gate bar spacing	`About 100 mm centre-to-centre on traditional wrought iron`	Decides whether a lock plate has to be welded	Centre of one bar to centre of the next, at lock height.
Clearance between door handle and gate handle	`3–7 mm door gap is common for flush-fitting gate locks`	—	With the gate closed, measure the gap between gate and frame.

Retrofit architectures that work

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.
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.

Two facts decide the design. First, the gate-to-door depth clearance: if it is under about 70 mm, only a slim body fits, and the market sells slim bodies precisely for this. Second, the mounting surface: a hollow bar cannot carry a lock, so a welded steel plate is part of the job, not an optional extra. Grille spacing, mortise cut-outs and flush-ness vary between gates, so a photo check before ordering is normal practice rather than a courtesy.

Related standards

SCDF CoC (Singapore)

Questions

Why do gate locks fail more often than door locks?

Because they are outdoors. Sun, rain and humidity attack the battery, the adhesive and the electronics. Look for an IP rating — products on the Singapore market are commonly IP54 to IP65 — and note that some makers advise sheltered installation only.

Can I fit a door smart lock on the gate?

Rarely. A door lock assumes a solid leaf with a mortise pocket. A gate gives you bars, a hollow stile and no pocket. Products built for gates exist for exactly this reason.

What about fire escape?

A gate must never become the reason someone cannot get out. The latch has to open from inside by hand with no power, and the gate must not obstruct the common corridor or escape route.

Sources

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