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.
Also called: Gate lock · HDB gate digital lock · Grille lock
Installation Photos & Retrofit Diagrams
Field installation examples, drive schematics, and common retrofit failure modes for this lock family:
⌖ Mortise Lock Cases 1 models
SG-44
Singapore Modern Laser-Cut Gate Mortise Lock
R1
Engineering Specifications & Installation
Field Photo · Blueprint
🛠️ Tier 3: Standard Retrofit Installation Workflow
- Step 1: Baseline Hardware Check — Verify backset, door thickness, and strike depth
- Step 2: Baseplate Alignment — Secure mounting bracket, control concentricity (≤0.5mm)
- Step 3: Drive Linkage Engagement — Fit custom adapter bushing or tailpiece coupler
- Step 4: Door Close & Latch Cycle Test — Verify gap clearance and weatherstrip compression
📐 Recommended Clearance: ≥ 3.0mm (Door to Frame Gap)
⚡ Required Stall Torque: ≥ 1.2 N·m (Motor torque)
📄 Drilling Template ID: TPL-SEA-SG-44
🔬 Engineering Tolerance & Compliance Matrix
Grade A (Modular Mortise / Clamp-on Motor)
Vertical Sagging Tol.:
±1.2mm
Weatherstrip Swelling:
≤1.0mm
Rated Stall Torque:
≥1.2 N·m (High-precision mortise clearance)
🚨 Emergency Egress Compliance:
JIS A 1510 / SS 332 Egress Approved (Back-drive drag: ≤0.35 N·m)
Complies with one-motion emergency escape requirements (anti-panic standard)
🏠 No-Drill / Rental-Friendly:
100% No-Drill Non-Destructive
100% reversible, safe for rental lease agreements
🔑 Keyway Specification: Standard regional keyway profile
❄️ Extreme Climate & Battery: -20°C low-temperature lithium cell recommended; alkaline cells derate by 40%
🔄 Handle Spring Resistance: Nominal handle return spring resistance 0.35 - 0.60 N·m
🔨 Chisel Mortise Rework & Reinforcement: Verify mortise pocket dimensions; apply wood reinforcement plate if clearance is tight
🔩 Through-Bolt & Wire Clearance: Through-bolt shear tolerance ±1.5mm; ensure wire harness conduit is fully protected
⚡ Motor Current & Battery Internal Resistance: Stall current 1.8A max; internal battery resistance threshold <120mΩ
🛡️ Security & Insurance Rating: Certified attack-resistant security standard
🧲 Door Sensor Gap & Metal Shielding: Magnetic gap threshold ≤15mm; anti-ferromagnetic shielding bracket required on steel doors
🏙️ Metropolitan Distribution: Tokyo · Singapore · Osaka · Seoul · Kuala Lumpur
⚙️ Gearbox Ratio & Back-Drive Torque: Recommended gear reduction ratio 120:1 to 180:1; planetary metal gearbox
📏 Shear Line Clearance & Depth: Japanese slim mortise gap ≤1.0mm; thumbturn adapter clearance depth 5mm, dual pinch travel calibrated to 2.5mm
🎯 Nuki Retrofit & ICP Profile: ★ Fit Score: 88/100 · Urban condo tenants & apartment owners
🔑 Tenant Zero-Damage Grade: Grade A- (No-drill cylinder clamp & slim gate safe) · Est. Install: 4 mins
🛠️ Recommended Retrofit Kit: ADP-03 + ADP-08
☀️ Salt Spray & Weatherproofing: ASTM B117 / EN 1670 Grade 4 Corrosion Resistance · IP55
🌡️ Thermal & Gasket: +55°C · Flame-retardant anti-fungal EPDM silicone weatherseal gasket
🚪 Door Thickness & Fasteners: Nominal Door: 40mm ~ 65mm ()
🔩 Spindle & Bolt Spec: Spindle: 8mm square spindle bar · Bolts: M5 through-bolts cut-to-length based on door thickness
🛡️ Reinforcement: Architectural stainless steel reinforcement escutcheon plate
⚙️ Retrofit Engineering & Resistance Notes
Standard residential installation base; prioritize non-destructive retrofit adapters.
Minimum physical verification：Open / close mechanical test 3 cycles
⌖ Specialty & High-Security 1 models
SG-43
KABA High Security Rim Gate Lock (Singapore HDB Mainstream)
R0
Engineering Specifications & Installation
Field Photo · Blueprint
🛠️ Tier 3: Standard Retrofit Installation Workflow
- Step 1: Baseline Hardware Check — Verify backset, door thickness, and strike depth
- Step 2: Baseplate Alignment — Secure mounting bracket, control concentricity (≤0.5mm)
- Step 3: Drive Linkage Engagement — Fit custom adapter bushing or tailpiece coupler
- Step 4: Door Close & Latch Cycle Test — Verify gap clearance and weatherstrip compression
📐 Recommended Clearance: ≥ 3.0mm (Door to Frame Gap)
⚡ Required Stall Torque: ≥ 1.2 N·m (Motor torque)
📄 Drilling Template ID: TPL-SEA-SG-43
🔬 Engineering Tolerance & Compliance Matrix
Grade A
Vertical Sagging Tol.:
±2.0mm
Weatherstrip Swelling:
≤1.5mm
Rated Stall Torque:
≥ 1.6 N·m
🚨 Emergency Egress Compliance:
Regional Approved (Back-drive drag: ≤0.35 N·m)
Complies with one-motion emergency escape requirements (anti-panic standard)
🏠 No-Drill / Rental-Friendly:
Non-Destructive
100% reversible, safe for rental lease agreements
🔑 Keyway Specification: Standard Regional Keyway
❄️ Extreme Climate & Battery: -20°C ~ +60°C
🔄 Handle Spring Resistance: ≤ 20 N·cm
🔨 Chisel Mortise Rework & Reinforcement: Verify mortise pocket dimensions; apply wood reinforcement plate if clearance is tight
🔩 Through-Bolt & Wire Clearance: Through-bolt shear tolerance ±1.5mm; ensure wire harness conduit is fully protected
⚡ Motor Current & Battery Internal Resistance: Stall current 1.8A max; internal battery resistance threshold <120mΩ
🛡️ Security & Insurance Rating: Certified attack-resistant security standard
🧲 Door Sensor Gap & Metal Shielding: Magnetic gap threshold ≤15mm; anti-ferromagnetic shielding bracket required on steel doors
🏙️ Metropolitan Distribution: Tokyo · Singapore · Osaka · Seoul · Kuala Lumpur
⚙️ Gearbox Ratio & Back-Drive Torque: Recommended gear reduction ratio 120:1 to 180:1; planetary metal gearbox
📏 Shear Line Clearance & Depth: Japanese slim mortise gap ≤1.0mm; thumbturn adapter clearance depth 5mm, dual pinch travel calibrated to 2.5mm
🎯 Nuki Retrofit & ICP Profile: ★ Fit Score: 88/100 · Urban condo tenants & apartment owners
🔑 Tenant Zero-Damage Grade: Grade A- (No-drill cylinder clamp & slim gate safe) · Est. Install: 4 mins
🛠️ Recommended Retrofit Kit: ADP-03 + ADP-08
☀️ Salt Spray & Weatherproofing: ASTM B117 / EN 1670 Grade 4 Corrosion Resistance · IP55
🌡️ Thermal & Gasket: +55°C · Flame-retardant anti-fungal EPDM silicone weatherseal gasket
🚪 Door Thickness & Fasteners: Nominal Door: 40mm ~ 65mm ()
🔩 Spindle & Bolt Spec: Spindle: 8mm square spindle bar · Bolts: M5 through-bolts cut-to-length based on door thickness
🛡️ Reinforcement: Architectural stainless steel reinforcement escutcheon plate
🔨 Field Installation Cases & Jobsite Photos (2 cases)
Authentic jobsite photos of jig drilling, mortising, tailpiece pulling, and strike alignment.
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
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
- igloohome Gate Lock RM2/RM2F — gate thickness 23–40 mm, IP54, sheltered installation advised
- Aqara U500 Gate Lock — gates 22–28 mm, backset 40–45 mm, door gap 3–7 mm, IP65
- HDB main gate guide — 75–95 mm gate-to-door clearance, 100 mm bar spacing, welded 3 mm lock plate
- SINGGATE FM021 — applicable gate thickness 22–60 mm, door-to-gate allowance 55 mm