What is the difference between a mortise and a deadbolt digital lock?

A mortise digital lock has its case set into a pocket in the door edge and combines a spring latch and a deadbolt in one handle set, so you unlock and open in one motion. A deadbolt digital lock has a single bolt and no handle; you keep your existing knob. Mortise cuts more timber, deadbolt cuts less and is easier to reverse.

Which digital lock type is best for an HDB wooden main door?

Both mortise and deadbolt bodies suit HDB timber doors. Choose a mortise lock if you want a new handle set with one-motion opening or your door already has a mortise pocket. Choose a deadbolt if you want to keep your current handle, are renting, or want the smallest cut-out. Rim locks are not recommended on wooden main doors.

Why are gate digital locks surface-mounted?

HDB metal gates are made from hollow steel sections and bars, so there is no solid edge to cut a lock pocket into. Gate digital locks therefore mount to the surface of the gate frame with brackets and fixings, and the bolt or hook engages a keep on the frame. Security depends on how firmly the body is anchored, not on a pocket.

Is a push-pull lock a different lock type from a mortise lock?

No. Push-pull and lever describe the handle style on the outside of the door, not the lock body inside it. Both styles are normally paired with a mortise body set into the door edge. Decide the body type first, then choose the handle that suits how your household opens the door. Deadbolt digital locks have no handle of their own.

Can I install a digital lock on a fire-rated HDB main door?

Often, but check first. HDB guidance says fire-rated entrance doors have a door closer that must not be removed, and replacing a door on a fire escape route needs a permit and a half-hour fire-rated door. Confirm whether your door is fire-rated, prefer the lock type that cuts least, and ask the supplier in writing to confirm the model is suitable before buying.

Types of Digital Locks Explained: Mortise vs Deadbolt vs Rim for Singapore Doors and Gates

11 October 2026

You are comparing digital locks for your HDB flat and every listing throws a different word at you: mortise, deadbolt, rim, push-pull, lever. These are the main types of digital locks sold in Singapore, and the words describe how the lock physically fits your door or gate. Pick the wrong type and the lock does not fit, or your installer cuts more out of the door than you expected.

We fit smart locks on wooden main doors and metal gates across Singapore, and this mechanical question comes up more often than fingerprint-versus-face. This guide explains each lock body type, what it means for your door, and which one suits a typical HDB or BTO entrance.

What is a lock body, and why is it separate from the electronics?

The lock body is the mechanical part that holds your door shut: the bolt, the case it sits in, and the hardware that moves it. The electronics, meaning the fingerprint reader, keypad, motor and app module, sit on top and tell that body when to open.

Two locks with identical sensors can have completely different bodies underneath, and the body decides whether the lock fits your door, how much timber or steel gets cut, and how hard it is to change later. Three body types cover almost everything sold for homes here: mortise, deadbolt and rim (surface-mounted).

What is a mortise digital lock?

A mortise lock is one whose lock case sits in a pocket cut into the edge of the door, with only a narrow faceplate showing on the door edge. The term describes only how the lock is fitted and says nothing about its quality, as the reference description of mortise locks puts it.

In a mortise digital lock, that case usually holds two things in one body: a spring latch that keeps the door shut every time it swings closed, and a deadbolt that locks it. One handle set operates both, so the outside handle carries the sensor and keypad, and the inside handle opens the door in one movement.

How it is installed: a rectangular pocket is cut into the door edge for the case, plus holes through the door face for the handle spindle and wiring. If your door already has a mortise pocket, the installer checks whether the new case matches it.
Security: the body is enclosed by the door on all sides, with room for a longer bolt and a sturdier mechanism than bolt-only designs. Cutting the pocket also removes timber from the door edge, so a well-fitted strike plate matters.
How much door is cut: more than any other type.
Changing locks later: easy if the next lock is also a mortise lock of similar size. Awkward if you later want a smaller deadbolt, because the large pocket has to be filled and covered.
Suits: solid wooden main doors, including HDB and BTO timber doors.

What is a deadbolt digital lock?

A deadbolt digital lock has a single solid bolt and nothing else: no spring latch, no handle. The bolt is thrown into the frame by a motor, key or thumb-turn, and because it has no spring it cannot be pushed back the way a latch can, as the standard description of a deadbolt explains.

Digital deadbolts keep your existing knob or handle for pulling the door open. The lock is a slim unit outside with the reader and keypad, a matching unit inside with the motor and battery, and a bolt case between them.

How it is installed: typically a hole through the door face for the body and a smaller bore in the door edge for the bolt. If your door already has a deadbolt or night latch above the handle, the digital deadbolt often reuses that cut-out; ask your installer to confirm on your door before you order.
Security: a well-made deadbolt into a solid frame is a strong lock. It relies on the strike plate and frame as much as the lock, so the installer should check the frame is sound.
How much door is cut: much less than a mortise lock. Changing later is simple, since the small cut-out takes another deadbolt or a cover plate.
Suits: wooden main doors where you want to keep the existing handle, and rented flats where you may need to restore the door.

The trade-off is two motions instead of one: unlock the deadbolt, then turn the knob. On a busy family door that is noticeable; on a door used a few times a day, it is not.

What is a rim lock, and why are gate locks surface-mounted?

A rim lock attaches to the surface of the door or gate rather than being set into its edge, as the reference description of rim locks defines it. The case sits on the inside face with a keep on the frame, so nothing is hollowed out.

On a wooden door this is the oldest and least secure arrangement, held on by screws from the inside, and the same reference notes rim locks are not used where high security is required. An HDB metal gate is different: it is made from hollow steel sections and bars, so there is no solid edge to cut a pocket into. Surface mounting is the practical option, and gate digital locks are built around it, fixing to the gate frame with the bolt or hook engaging a keep on the wall-side frame.

How it is installed: fixed to the gate frame with brackets and a small amount of drilling. The reader faces the corridor; the battery pack and release sit inside.
Security: depends on how firmly the body is anchored and how the bolt engages the keep. A good gate lock keeps its fixings out of reach from the corridor side.
How much gate is cut: very little, and the next lock mounts to the same frame. Suits metal gates and grilles; for wooden main doors, choose a mortise or deadbolt body instead.

If you are deciding whether the smart lock belongs on the gate, the door or both, our gate smart lock guide covers the gate side in full.

Are lever handle and push-pull digital locks different lock types?

No. Lever and push-pull describe the handle on the outside, not the body inside the door, and both are normally paired with a mortise body. Decide the body first, then the handle.

A lever handle digital lock looks like a conventional handle with a reader on or above it: authenticate, then press the lever down. A push-pull lock replaces the lever with a straight bar you push or pull in the direction the door swings; our explainer on what a push-pull smart lock is and who it suits covers it in full. Deadbolt digital locks have no handle of their own: you keep the knob or lever already on your door.

Mortise vs deadbolt vs rim: which digital lock type for an HDB door or gate?

For a wooden HDB main door, choose a mortise lock if you want one-motion opening and a new handle set, or a deadbolt if you want minimal cutting and to keep your existing handle. For a metal gate, you need a surface-mounted gate lock, because there is no edge to cut into.

Lock body type	Where it sits	Door or gate cut	Opening	Best for
Mortise	Pocket in the door edge, latch and bolt in one case	Most: deep edge pocket plus face holes	One motion via the handle	Wooden main doors; busy family entrances
Deadbolt	Small bolt case, units on both door faces	Least on a wooden door; often reuses an existing cut-out	Two motions: unlock, then turn your handle	Renters, keeping the existing handle, minimal change
Rim / surface-mounted	On the face of the door or gate frame, keep on the frame	Fixing holes only	Depends on model; many gate locks auto-relock	Metal gates and grilles; not for wooden main doors

One shortcut: if your door already has a mortise pocket from an earlier push-pull or lever digital lock, a new mortise lock is the natural replacement, since a deadbolt would leave a hole to fill. If your door has a knob and a separate deadbolt or night latch, the digital deadbolt is the lighter-touch option.

Can I fit a digital lock on a fire-rated HDB main door?

Often yes, but check first. Some HDB main doors are fire-rated, and the question is whether a particular lock body, especially one that needs a new pocket cut, keeps the door performing as intended. Confirm your door type and the lock's compatibility before you buy.

HDB's renovation guidance says a permit is needed to replace a main entrance door along a fire escape route, such as one facing a staircase or lift lobby, and that the replacement door and frame must be half-hour fire-rated and complete with a door closer. HDB's home care guide adds that all fire-rated doors at the entrance of HDB flats have a door closer, a self-closing safety device that must not be removed.

Find out whether your door is fire-rated. A door closer and a rating label on the edge or frame are common signs, and HDB or your Town Council can confirm.
Never remove or disable the door closer to make a lock fit. Adjust it instead.
Prefer the lock type that cuts least, and ask the supplier in writing whether the model is suitable for your door. We make no fire-rating claims for OpenTouch locks, so if your door is fire-rated, raise it with us on WhatsApp before ordering and we will tell you what we can and cannot confirm.
Replacing the door leaf itself is a permit-level job, covered in our guide to HDB digital lock rules and approvals.

Which OpenTouch lock matches each type?

The Touch i19 is a slim mortise lock for wooden front doors, and the Touch i9 is a slim fingerprint deadbolt for wooden front doors. Both are S$459 in Standard trim (fingerprint, anti-peeping PIN, Mifare card, mechanical key) or S$499 in Premium trim, which adds facial recognition, WiFi and app control.

Pick the i19 (mortise) if you want latch and bolt in one body with one-motion opening, your door already has a mortise pocket, or the door is a busy family entrance.
Pick the i9 (deadbolt) if you want to keep your existing handle, you are renting or may need to restore the door, or you want the smallest change to the timber.
Pick neither if your entrance is a metal gate. The Touch 200, Touch 200 Pro and Touch 300 Pro are gate locks for metal gates, from S$319. The Touch 200D is a further wooden-door option with built-in WiFi at S$319; confirm its fit for your door with us before ordering.

Every OpenTouch lock includes free certified installation across Singapore and a 2-year local warranty. We do not publish door-thickness ranges per model, so send a photo of your door edge and existing lock on WhatsApp and we will confirm fit first.

Still unsure which type fits your door?

Start with the body, then the handle, then the electronics. Browse the range at our store, or send a photo of your door or gate to +65 9139 0778 on WhatsApp and we will tell you which type fits, even if the answer is a different lock from the one you had in mind.