Glass Door Locks: EM Lock with U Bracket vs Drop Bolt vs Fingerprint Glass Lock

Quick answer: For a glass door, the three common electronic options are an EM (electromagnetic) lock with a U bracket, a drop bolt lock, and a fingerprint glass door lock. An EM lock is a good choice for office entrances that open with a card, PIN or exit button. A drop bolt suits doors where you want a strong fail-secure hold. A fingerprint glass door lock suits a single door where you want a self-contained lock with no separate controller. The right one depends on your door type (frameless or framed), how the door is used, and whether it must open during a power cut.

Glass doors are common in offices, clinics, showrooms and salons, but they do not take locks the way wooden doors do. This guide compares the three options so you can choose with confidence.

Frameless glass vs framed glass: why it matters

Before choosing a lock, identify your door type.

• Frameless (toughened) glass doors have no metal frame around the glass. Locks must be clamped to the glass using a special bracket, and holes or clamps need to suit the glass thickness. Never drill toughened glass yourself, because it can shatter.
• Framed glass doors have an aluminium or steel frame. Locks can often be fixed to the frame, which gives more options.

Measure the glass thickness and note whether the door is single or double leaf, and whether it opens inward or outward. These details decide which bracket and lock you can use.

Option 1: EM lock with U bracket

An EM lock is a magnet fixed to the door frame or header, with a metal plate fixed to the door. When powered, the magnet holds the plate and the door stays locked. When power is cut, the door releases.

A U bracket is used on frameless glass doors to hold the armature plate on the glass edge. It lets you fit an EM lock without drilling the glass.

• Works well for: office entrances with access control, where a card, PIN, fingerprint or push button releases the door.
• Remember: the door unlocks when power fails, so it is considered fail-safe. This is useful for fire safety, but it also means your door is unlocked during a power cut unless you add a battery backup.
• Needs: a power supply and a controller or reader to operate.

To choose the right holding force, read our EM lock buying guide. You can browse EM locks and glass door locks in one place.

Option 2: Drop bolt lock

A drop bolt lock has a bolt that drops into a bracket when the door is closed. When power is applied, the bolt moves, depending on the model, either to lock or release the door.

• Works well for: doors where a firm mechanical hold is preferred, such as storage rooms, server rooms and back-office doors.
• Remember: some drop bolts are fail-secure, which means they stay locked in a power cut. That is good for security, but you must have an emergency exit plan and a mechanical release.
• Needs: a suitable bracket for glass, a power supply and a controller.

Option 3: Fingerprint glass door lock

A fingerprint glass door lock is a self-contained lock that clamps to the glass and opens by fingerprint, and often by card, PIN, key or app as well, depending on the model. Battery-operated models need no wiring to the door.

• Works well for: a single glass door in a small office, clinic or salon where you want simple keyless entry.
• Remember: check battery life, the emergency key option and whether the lock suits your glass thickness.
• Needs: installation as per the model's instructions, with the correct door type and thickness.

EM lock vs drop bolt vs fingerprint glass lock: comparison

Feature	EM lock + U bracket	Drop bolt lock	Fingerprint glass door lock
How it holds	Magnet holds a plate	Bolt drops into a bracket	Lock body clamped to glass
Behaviour in power cut	Releases	Depends on model; many stay locked	Battery models keep working
Needs separate controller	Yes	Yes	No, self-contained
Wiring	Yes	Yes	Little or none
Best for	Access-controlled entrances	Rooms needing a firm hold	Single doors, simple use

How to choose: a simple decision guide

1. Do you need card, PIN or attendance integration? Choose an EM lock or drop bolt with a controller. Read our door access control systems guide for the parts you need.
2. Is it a single door with few users and no wiring? A fingerprint glass door lock is the simplest.
3. Is the door on an escape route? Choose a lock that releases without a key and keep a push-to-exit button inside. Check local fire safety rules.
4. Is power cut a concern? Add a battery backup for powered locks, or choose a battery-operated lock.
5. Is the glass frameless? Use brackets designed for glass and never drill toughened glass.

Frequently asked questions

Can I fit an EM lock on a frameless glass door?

Yes, using a U bracket or a glass door bracket made for this purpose. It clamps to the glass, so you do not need to drill it. Check that the bracket suits your glass thickness.

Will an EM lock open during a power cut?

Yes, it releases when power stops. If you want the door to stay locked in a power cut, add a battery backup or choose a different lock type.

Which is better for an office glass door, EM lock or fingerprint lock?

If you want to integrate card, PIN or attendance with the door, an EM lock with a controller is the more flexible choice. For a single door with simple needs, a fingerprint glass door lock is easier to fit.

Do glass door locks need an exit button?

Powered locks such as EM locks and drop bolts usually use an exit button so people can leave without a card. Plan for one, and for an emergency release, on any escape route.

Safety and code points for glass doors

• Escape routes: Doors that people use to leave in an emergency should open easily from the inside. Add an exit button and, where required, an emergency release.
• Fire alarm link: In some buildings, locks are connected to the fire alarm so they release when the alarm sounds. Ask your fire safety consultant whether this applies to you. See our fire alarm basics guide.
• Glass protection: Use the correct brackets and pads for the glass thickness, and never drill toughened glass.
• Door alignment: A door that sags or drops will not line up with an EM lock plate, so check the hinges.

How the whole glass-door access system fits together

1. Reader or keypad outside the door, where the visitor or staff member presents a card, PIN or fingerprint.
2. Controller that checks the credential and sends a release signal.
3. Power supply for the lock and controller, with battery backup if the door must stay locked during power cuts.
4. Lock, which is an EM lock, drop bolt or fingerprint lock fitted to the glass.
5. Exit button inside so people can leave without a card.
6. Door closer so that the door closes fully after each use.

This chain is explained further in our door access control systems guide, and power supply sizing is covered in our power supply guide.

Single door vs double door vs sliding glass door

Door type	Common approach	Keep in mind
Single swing door	One EM lock or one fingerprint lock	Check which side the hinges are on
Double swing door	Two locks, or a lock fitted at the meeting edge	Both leaves must align and close together
Sliding glass door	Special sliding-door lock options	Standard bracket types may not suit; check the product description

More questions buyers ask

Can a fingerprint lock be fitted on a double glass door?

It can be fitted on one leaf, with the other leaf held by a bolt or by a second lock. Check the lock's instructions for double-door fitting.

Do I need a door closer?

Yes, for most electronic locks. A closer makes sure the door closes fully so the lock can engage.

How do I choose the holding force of an EM lock?

The holding force is measured in pounds or kilograms. Choose a rating suited to the door and its use, and see our EM lock buying guide for the details.

Shop Glass Door Locks at NavKar Systems

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