Deadlock vs Deadlatch: Which Do You Need?

Walk into any hardware store and you will see shelves of locks labelled deadlock, deadlatch, deadbolt, nightlatch and entrance set. The names sound similar and the packaging rarely explains the difference. Yet choosing the wrong one can leave a door less secure than you think, or make it frustrating to use every day.

This guide explains the two locks people most often confuse, the deadlock and the deadlatch. We cover how each one works, where each suits a home or business in Bankstown, the safety trade-offs, and how to decide which one belongs on each of your doors.

What a deadlock is

A deadlock is a lock with a solid bolt that only moves when you turn a key or, on some models, a thumb turn on the inside. The bolt has no spring. Once it is thrown into the door frame, it stays there until someone deliberately turns the key back.

That is the whole point of a deadlock. Because the bolt is not spring-loaded, it cannot be pushed back with a card or a thin tool slipped between the door and the frame. A properly fitted deadlock, with a solid strike plate screwed deep into the frame, is one of the strongest locks you can put on a residential door.

Deadlocks come in two main styles:

• Cylinder deadlocks sit on the face of the door, usually above the handle. They are the most common type on Sydney homes.
• Mortice deadlocks sit inside a pocket cut into the edge of the door. They are common on older timber doors, including many in post-war homes around Punchbowl and Bankstown.

Some deadlocks are double-cylinder, which means a key is needed on both sides. Others have a thumb turn inside, so you can lock and unlock from inside without a key.

What a deadlatch is

A deadlatch looks similar but works differently. It has a spring-loaded latch bolt, which means the bolt springs into the frame automatically every time the door closes. You do not need to turn a key to lock the door. Pull it shut and it latches.

What makes it a deadlatch, rather than a simple latch, is a small extra plunger beside the main bolt. When the door is closed, that plunger is pressed in by the strike plate, and it locks the main bolt in place. This stops someone from pushing the bolt back with a card, a trick that works on a basic spring latch.

Most deadlatches also have a way to deadlock the latch, usually by turning the key or pressing a button on the inside. Once deadlocked, the inside handle or knob will not open the door either. This is useful when you are leaving the house for the day.

In Australia, many people call these locks nightlatches or rim locks, because they are often mounted on the inside face of the door with a cylinder showing on the outside.

The key differences side by side

Here is how the two compare in everyday use.

Neither lock is "better" in every situation. They do different jobs.

When a deadlock is the right choice

A deadlock suits doors where strength matters more than convenience. Typical examples include:

• Front doors on houses, especially when used alongside a separate latch or entrance set for daily use.
• Back and side doors that are out of sight from the street. These are common entry points for burglars because they are not overlooked. In larger blocks in Condell Park and Revesby, side and rear entries deserve the same quality lock as the front.
• Garage internal doors that lead into the house.
• Doors in rentals or shared homes where you want to know the door is properly locked, not just latched.

The main downside is that you must remember to turn the key. A deadlock that is not locked offers no protection at all.

When a deadlatch is the right choice

A deadlatch suits doors where people come and go constantly and you want the door to secure itself without anyone thinking about it. Typical examples include:

• Unit entry doors, where residents expect the door to lock behind them.
• Shop back doors used for deliveries throughout the day.
• Office doors that staff open and close repeatedly.
• Front doors in busy households, where children may forget to lock up.

The main downside is lockouts. Because a deadlatch locks every time the door closes, it is very easy to step outside to grab the mail and hear the door click shut behind you, with the keys still inside. A large share of the lockouts we attend around Bankstown involve self-locking latches on unit doors.

Using both on the same door

Many Sydney homes use both: a deadlatch or entrance set for everyday use, and a separate deadlock above it for extra security when the house is empty or at night.

This combination gives you the best of both locks. During the day, the door latches itself and you can come and go easily. When you leave the house or go to bed, you turn the key in the deadlock and the door is much harder to force.

If your door has both, make sure they use the same key. A locksmith can usually key them alike, which means one key opens both locks. It is a small change that makes daily life much easier.

Safety: getting out in an emergency

Security is only half the picture. You also need to be able to get out quickly if there is a fire or another emergency.

A double-cylinder deadlock that needs a key on the inside can trap people if the key is not nearby. This is a real risk, particularly for children, older people and visitors who do not know where the key is kept.

If you choose a double-cylinder deadlock, keep the key somewhere everyone in the house knows, close to the door but out of reach from outside through a window or letterbox. Many families choose a deadlock with an internal thumb turn instead, which gives strong security from outside while allowing a quick exit.

For businesses, the rules are stricter. Some doors in commercial premises are required exits and must open from inside without a key. If you are unsure whether a door is a required exit, check with your building manager or certifier before choosing a lock. Our commercial locksmith page explains how we approach this.

The strike plate matters as much as the lock

Whichever lock you choose, it is only as strong as what it locks into. The strike plate is the metal plate on the door frame that receives the bolt. When someone kicks a door, the force goes straight into the strike and the frame around it.

A strong lock fitted with short screws into a soft timber frame can fail easily. A heavier strike plate, fixed with long screws that reach into the wall framing behind the door jamb, makes a far bigger difference than many people expect. It is one of the cheapest and most effective security upgrades available.

When we fit or replace a lock, we always check the strike. If the door has dropped or the frame has moved, the bolt may not be fully entering the strike, which weakens the lock and makes it stiff to use. Our lock repair page explains how we fix this.

Common mistakes to avoid

• Fitting only a deadlatch on a back door that is rarely used. A deadlock is usually the better choice for doors that are not watched.
• Leaving the deadlock unlocked. It only works when you turn the key.
• Ignoring a deadlatch plunger that no longer works. If the door gap is too big, the plunger may not press in, and the latch can be pushed back with a card. A locksmith can adjust the strike so it works properly.
• Using a double-cylinder deadlock with the key kept far away. This can trap people in an emergency.
• Buying the cheapest lock available. Low-quality locks wear out quickly and may be easy to defeat.

Which lock for each door

Here is a simple starting point for a typical Bankstown home.

• Front door: an entrance set or deadlatch for daily use, plus a deadlock with an internal thumb turn.
• Back door: a quality deadlock, ideally keyed alike with the front door.
• Side door or laundry door: a deadlock.
• Garage internal door: a deadlock.
• Security screen doors: a keyed screen door lock suited to the screen frame. Our security locksmith page covers screen doors in more detail.
• Unit entry door: often a deadlatch, with a deadlocking function for when you are away.

For businesses, the choice depends on the door's use, the number of staff and any exit requirements.

How a locksmith can help

Choosing the right lock is easier when someone looks at the actual door. A locksmith can check:

• the door material and thickness;
• the existing holes and whether a new lock will fit them;
• the condition of the frame and strike;
• whether locks can be keyed alike;
• whether a door is a required exit.

We fit both deadlocks and deadlatches across Bankstown, Yagoona, Punchbowl, Condell Park, Greenacre and Revesby. See our door lock installation page for how we fit new locks, or our lock replacement page if you want to swap an existing lock.

The bottom line

A deadlock gives strong, deliberate security, but only when you remember to lock it. A deadlatch locks itself every time the door closes, which is convenient but makes lockouts more likely. Many doors benefit from both, keyed alike so a single key does the job.

If you are unsure what suits your doors, call us on 02 5657 6414, 7 days from 7:00am to midnight, or request a quote through our contact page. Send a photo of the door and we will tell you which lock fits best and what it will cost before any work starts.