Deadlock vs Deadlatch: Which Lock Does Your Door Need?

"Deadlock" and "deadlatch" sound almost the same, and many people use the words interchangeably. They are different locks that work in different ways, and choosing the wrong one for a door can leave it less secure or make it harder to get out in an emergency. This guide explains the difference in plain language and how to decide which suits your door.

How a deadlock works

A deadlock has a solid bolt that is moved in and out by turning a key or a thumb-turn. When the bolt is thrown into the frame, it cannot be pushed back by pressure on the bolt itself. That is the "dead" part: the bolt is locked in position until it is turned back.

Key features:

• The door does not lock automatically when it closes. You have to lock it.
• The bolt usually extends further into the frame than a latch, which makes it harder to force.
• Many deadlocks are key-operated on both sides, or key outside and thumb-turn inside.

Deadlocks are often fitted in addition to another lock, giving the door two locking points.

How a deadlatch works

A deadlatch has a spring-loaded latch that clicks into the frame as the door closes, so the door locks automatically. A small secondary plunger next to the latch is pushed in when the door is closed, and that "deadlocks" the latch so it cannot be slipped back with a card or thin tool.

Key features:

• The door locks itself when closed. Convenient, but it is also why people lock themselves out.
• The latch can usually be opened from inside with a knob or lever, which is helpful for a quick exit.
• Many deadlatches can be key-locked from inside or outside for extra security.

Deadlatches are very common on apartment entry doors and on the front doors of houses.

The key differences side by side

Which is more secure?

As a rule, a quality deadlock with a long bolt, properly fitted into a strong frame, offers more resistance to forced entry than a deadlatch alone. But "properly fitted" matters more than the label. A deadlock screwed into a weak frame with short screws can be weaker in practice than a well-fitted deadlatch. That is why we look at the strike plate and frame as part of any security upgrade.

For many homes, the best answer is both: a deadlatch for everyday convenience, and a deadlock for when you are away or at night.

The fire-safety trade-off

Security is not the only thing a lock has to do. In a fire, people need to get out quickly, often in the dark and in a panic.

• A deadlock that needs a key on the inside can trap people if the key is not nearby. Never leave yourself unable to get out quickly.
• A thumb-turn on the inside allows quick exit, but on a door with glass nearby, someone could break the glass and reach the thumb-turn.
• Apartment entry doors are often fire-rated and part of the building's fire safety system. Only suitable hardware should be fitted, and changes may need building approval.

There is no single answer for every home. On a solid door without glass, a thumb-turn inside is often sensible. On a door with glass panels, such as many Federation front doors in Waverley and Queens Park, a key-operated deadlock with the key kept nearby (but never in the lock) may be better. We talk this through with you before installing anything.

Which suits common eastern-suburbs doors?

Apartment entry doors

Most Bondi Junction and Bondi apartments already have a deadlatch, often specified by the building. Many residents add a deadlock or replace the deadlatch with a better one. Check strata rules first, because the door is usually fire-rated. See our guide to apartment security.

Terrace and Federation front doors

Older solid timber doors often have an original mortice lock or a rim latch. Adding a quality deadlock is one of the most effective upgrades, as long as the timber is sound and the cut-outs are made carefully. See our heritage door locks guide.

Back doors and laundry doors

These are often overlooked and frequently have only a basic latch. A deadlock here is usually worthwhile, especially on terraces with rear-lane access in Paddington.

Shopfronts

Commercial glass doors usually need narrow-stile hook-bolt or deadbolt locks designed for aluminium frames. See commercial locksmith.

Signs your current lock is the wrong type

• You keep locking yourself out → a deadlatch is doing exactly what it is designed to do; consider habits, a spare key, or a different setup.
• The door only has a spring latch with no deadlocking plunger → it may be possible to slip, and an upgrade is worth considering.
• You cannot easily get out from inside → review fire safety straight away.
• The bolt barely enters the frame → the strike may need adjusting, or the lock may be wrong for the door.

Common myths about deadlocks and deadlatches

"A deadlatch is as good as a deadlock." Not quite. A good deadlatch is far better than a plain spring latch, but its bolt is usually shorter, and it only deadlocks when the plunger is fully pressed in by a correctly aligned strike. If the door has dropped, the plunger may not engage at all, leaving the latch slippable. A deadlock's bolt does not depend on that alignment in the same way.

"More locks always means more security." Adding locks helps only if each is fitted into solid timber and a strong frame. Three locks screwed into a weak jamb are only as strong as the jamb. Often a single reinforced strike plate does more than an extra lock.

"Double-cylinder deadlocks are always safest." Key-only on both sides prevents someone reaching through glass to open the door, but it can trap people inside in a fire if the key is not at hand. It is a trade-off, not an automatic upgrade.

"Expensive locks cannot be opened." Every lock can be defeated with enough time and the right tools. Good locks buy time and make entry noisy and difficult. That is what security is about — deterrence and delay, not invincibility.

Maintenance for both types

Both locks last longer with a little care:

• Check the strike alignment. If you have to push, pull or lift the door to lock it, the bolt is rubbing. Adjusting the strike prevents wear. See lock repair.
• Use the right lubricant. A dry graphite or lock-specific lubricant once or twice a year. Avoid general-purpose oils, which collect grit.
• Watch for salt. Near the beach in Bondi and North Bondi, salt air corrodes external locks faster. Clean and lubricate more often.
• Do not force a stiff key. A key that needs force is a warning. Forcing it can snap the key in the lock.

A quick decision guide

• You want the door to lock behind you automatically → deadlatch, plus a spare key plan.
• You want maximum resistance when you are away → add a quality deadlock fitted into a reinforced strike.
• The door has glass near the lock → consider a key-operated deadlock and keep the key close by, never in the lock.
• It is a fire-rated apartment door → check with your building before changing anything.
• It is a heritage door → choose hardware that suits the door and have the cut-outs made carefully.

What about rentals?

If you rent, you generally need your landlord's consent before changing or adding locks in NSW, with some exceptions. Many landlords are happy to approve a deadlock because it protects their property too. Ask in writing, explain what you want fitted, and keep a copy of the approval. If the landlord pays for the work, they will usually want a copy of the new keys. Our guide to NSW lock change rules explains the basics, and we are happy to talk to your agent directly.

How we help you choose

When you ask us about a new lock, we look at the door, the frame, the glass, how you use the door and any building rules. Then we explain the options and the cost, and you decide. We can then install the lock or replace your existing one properly.

Talk to a Bondi Junction locksmith

Not sure which lock your door needs? Call Lizzy Locksmith Bondi Junction on 02 6423 0404, open 7 days, 8:00am – 7:00pm, or send a quote request with a photo of the door and current lock.