"Deadlock" and "deadlatch" sound almost identical, and plenty of people use the words interchangeably. On the door, they behave very differently. Choosing the wrong one can mean a front door that is easier to force than you think, or a self-locking door that keeps shutting you out on the way to the beach. This guide explains the difference plainly and helps you decide what suits your door.

What a deadlatch is

A deadlatch is a spring-loaded lock. When you close the door, the bolt springs into the strike plate automatically, so the door latches shut without you doing anything. You open it from the outside with a key and from the inside with a handle, knob or snib.

The "dead" part refers to a small extra plunger beside the main latch. When the door is fully closed, this plunger is pressed in and stops the latch being pushed back with a card or thin tool. Many deadlatches can also be "deadlocked" with a key or snib so the inside handle will not open them either.

Strengths of a deadlatch:

The door latches every time it closes, so it is never left simply pulled to.
It is convenient for busy households and tenants coming and going.
Good models resist simple slipping attacks when the door is properly aligned.

Weaknesses of a deadlatch:

It is easy to lock yourself out, because the door locks behind you.
The bolt is spring-loaded and usually shorter than a deadlock's bolt, so it offers less resistance to force.
If the door has dropped or the strike is misaligned, the guard plunger may not engage, leaving the latch easier to slip.

What a deadlock is

A deadlock has a solid bolt that only moves when you turn a key or thumb turn. It does not spring. When you throw the bolt, it extends deep into the frame and stays there until you deliberately turn it back.

Strengths of a deadlock:

A longer, solid bolt that cannot be pushed back without turning the cylinder.
Generally much better resistance to force than a latch alone.
You never get locked out by a door swinging shut, because it does not lock itself.

Weaknesses of a deadlock:

It only protects you if you remember to lock it.
Models that need a key on the inside can slow your escape in a fire.

The fire-safety point people miss

Some deadlocks need a key on both sides. If the key is not in the lock or nearby during a fire at night, getting out can be dangerous, particularly for children, older residents and guests who do not know where the key is kept.

For homes and units, we usually recommend a deadlock or deadlatch that can be opened from the inside with a thumb turn or handle, without a key. Fire and Rescue NSW also advises keeping exits easy to open from the inside. If your current lock needs a key to get out, it is worth discussing alternatives.

Which is better for a front door?

For many Coogee homes, the best answer is both: a deadlatch for everyday convenience plus a separate deadlock for when you go out or go to bed. That combination gives you a door that is never left unlatched, plus a strong bolt when security matters most.

Where only one lock is practical, the choice depends on the door and how you use it:

Older timber front doors on houses and semis often benefit from adding a quality deadlock above the existing latch.
Apartment entry doors often use a deadlatch that can be deadlocked from inside, but fire-rated doors have rules about what hardware can be fitted. Check with your strata manager first.
Rental properties often suit a deadlatch so the door is always secured, with a thumb turn for safe exit.
Back doors to rear lanes, common behind Randwick and Waverley terraces, are a frequent weak point and are good candidates for a solid deadlock with a reinforced strike.

Our door lock installation and security locksmith pages explain how we assess each door.

Shops and commercial doors

Commercial doors take far more use than residential ones, and the trade-offs change.

Glass shopfront doors often use a mortice deadlock or hook bolt designed for aluminium frames.
Café and restaurant rear doors need to meet exit requirements while staying secure after close.
High-traffic doors wear latches quickly, and regular adjustment matters.

For business premises, see our commercial locksmith page.

Why the strike plate matters as much as the lock

Whichever lock you choose, it is only as strong as the frame it locks into. A deadlock bolt that sits in a thin strike plate fixed with short screws into soft timber can be forced surprisingly easily. Upgrading to a heavier strike secured with long screws into the frame stud often adds more security than changing the lock itself.

Alignment is the other half. If a door has dropped, a deadlatch's guard plunger may not engage, and a deadlock bolt may not throw fully. Doors on sloping streets in Clovelly or older homes near the beach move over time. If you have to lift or push the door to lock it, have it adjusted; our lock repair page explains how.

Signs your current lock needs attention

The key is stiff or needs jiggling.
The bolt does not extend fully.
You need to pull or lift the door to lock it.
The latch does not catch every time.
The lock wobbles on the door.
Corrosion is visible on an ocean-facing door.

Most of these can be repaired. Some mean the lock has reached the end of its life. Our guide rekey or replace locks? helps you decide.

Choosing quality hardware

When comparing locks, look for:

a solid metal body rather than light pressed metal;
a long bolt throw for deadlocks;
a guarding plunger on deadlatches;
a thumb turn or handle for keyless exit from inside;
a cylinder that can be rekeyed later; and
a finish suited to coastal air if you live near the water.

Price alone does not tell you quality, and the most expensive option is not always the right one for your door.

A simple decision guide

Ask yourself:

Do I want the door to lock automatically when it closes? If yes, you want a deadlatch.
Do I want the strongest possible bolt when I leave or sleep? If yes, add a deadlock.
Can everyone get out quickly without a key? If not, change the hardware.
Is the frame solid and the door aligned? If not, fix that first.
Is the door fire-rated or under strata control? If so, check what is allowed.

Real situations, real choices

These examples show how the deadlock-or-deadlatch question plays out on actual doors around Coogee.

The family who kept locking themselves out. A household with teenagers had a deadlatch on the front door. It locked every time the door closed, and someone was locked out almost weekly. They did not want a door that could be left unlatched either. The answer was to keep the deadlatch, add a keypad-free routine of a spare key with a neighbour, and teach the household to use the snib when stepping out to the bins. A lock change was not needed at all.

The terrace with only a deadlock. An older terrace had a strong deadlock but nothing else. When the owner forgot to lock it, the door simply sat closed but unsecured. Adding a deadlatch below the deadlock meant the door always latched, while the deadlock still gave extra strength at night.

The rental with a key-inside deadlock. A rental unit had a deadlock that needed a key on both sides. The tenant often left the key in the inside cylinder, which defeated the purpose, and the landlord worried about fire exit. Replacing it with a deadlatch that could be deadlocked from outside but always opened from inside with a handle solved both problems.

The café rear door. A café needed its rear door to be secure overnight but quick to open from inside. A commercial deadlock with a thumb turn inside, fitted with a heavy strike into a steel frame, met both needs.

Quick terms, explained

Backset: the distance from the door edge to the centre of the lock. Locks must match the door's backset.
Strike plate: the metal plate in the frame that the bolt or latch enters.
Snib: a small button or lever that holds a latch locked or unlocked.
Thumb turn: a small knob inside that turns a deadlock without a key.
Throw: how far a bolt extends into the frame.

The honest summary

A deadlatch locks itself and is convenient; a deadlock is stronger but only works when you use it. For many front doors, the best setup is both, with keyless exit from inside and a properly fixed strike plate.

If you would like advice on your own doors in Coogee or nearby, call Local Coogee Locksmith Service on 02 5023 1337, open 7 days, 7:00 AM to 12:00 AM, or request a quote. You can also read about our lock replacement service or contact us.

Deadlock vs Deadlatch: Which Lock Does Your Door Need?