When it comes to securing your home, understanding the hardware on your doors is a great place to start. Two of the most common door locking mechanisms you'll encounter in New Zealand homes are the deadbolt and the latch — and while they're often used together, they work in very different ways. Knowing the difference helps you make smarter decisions about your home's security.
How a Latch Works
A latch (sometimes called a spring latch or a tubular latch) is the mechanism that holds a door closed when you push or pull it shut. It features a spring-loaded, angled bolt — often called a latch bolt or snib — that retracts automatically as the door closes and springs back into the strike plate on the door frame.
Because the latch bolt is spring-loaded, it doesn't require a key or a turn of a knob to engage. This makes latches very convenient for everyday use: the door clicks shut behind you without any extra effort. Most interior door handles and many exterior knob sets include a latch mechanism.
The security limitation of latches
The angled shape of the latch bolt is also its weakness. With enough force — or a credit card-style tool — a latch can sometimes be pushed back and the door opened without a key. For this reason, latches alone are not considered sufficient security for exterior doors.
How a Deadbolt Works
A deadbolt is a separate locking bolt that is moved entirely by mechanical means — a key from outside or a thumb-turn from inside. Unlike a latch, a deadbolt has no spring mechanism. The bolt is solid and square-ended, and once thrown (extended), it sits firmly in the strike plate and cannot be pushed back without operating the lock.
This makes deadbolts significantly more resistant to forced entry. A quality deadbolt with a reinforced strike plate and long fixing screws is one of the most effective and affordable security upgrades you can make to an exterior door.
Types of deadbolts
- Single-cylinder deadbolt – Keyed on the outside, thumb-turn on the inside. The most common type for residential use.
- Double-cylinder deadbolt – Keyed on both sides. Useful where there is glazing near the door, but can be a fire safety risk if you can't find the key quickly in an emergency.
- Deadlatch – A combination of a latch and a deadbolt in one unit, common on many NZ entry doors.
Key Differences at a Glance
| Feature | Latch | Deadbolt |
|---|---|---|
| Bolt shape | Angled / tapered | Square / flat |
| Spring-loaded | Yes | No |
| Engages automatically | Yes | No — must be locked manually |
| Key required to lock | No | Yes (or thumb-turn) |
| Security level | Low–medium | High |
| Typical location | Interior & exterior doors | Exterior doors |
| Forced entry resistance | Low | High (with good strike plate) |
What NZ Homes Typically Use
Most New Zealand exterior doors are fitted with a combination lockset — a handle or knob with a latch, plus a separate deadbolt above or below it. This gives you the convenience of a self-latching door alongside the security of a deadbolt you can throw when you're home or leaving.
If your home only has a latch on the front door, upgrading to include a deadbolt is a straightforward and worthwhile improvement. BRANZ research consistently highlights door and window security as a key factor in home safety and insurance considerations.
Choosing the Right Hardware
When selecting locks for your home, look for products that meet Australian/New Zealand Standards — in particular, AS 4145 covers mechanical locks and latches. Quality brands available through NZ suppliers include Lockwood, Gainsborough, and Whitco, all widely stocked at Bunnings and Mitre 10.
Key things to consider:
- Grade/rating — Higher-grade locks offer better resistance to picking, drilling, and forced entry.
- Strike plate quality — A deadbolt is only as strong as its strike plate. Use a heavy-duty strike plate fixed with screws at least 75 mm long to reach the door framing stud.
- Door material and condition — Even the best lock won't perform well in a warped or poorly fitting door frame.
- Keying alike — A locksmith can often key multiple locks to the same key for convenience.
Renters and the Healthy Homes Standards
If you're a landlord, it's worth knowing that Tenancy Services Healthy Homes Standards include requirements around draught stopping and building security. Ensuring exterior doors have functioning, secure locks is part of your obligations as a landlord.
When to Call a Professional
While a confident DIYer can replace a like-for-like lockset on an existing door, there are situations where it pays to call a qualified locksmith:
- You're locked out of your home
- You've moved into a new property and want to rekey or replace locks
- You want a security assessment of your whole home
- The door frame or door itself needs modification to fit new hardware
- You're installing a smart lock or electronic access system that may involve low-voltage wiring
Note: Any electrical wiring work — even for smart locks — that goes beyond simple battery-operated devices may constitute restricted electrical work under New Zealand law and must be carried out by a registered electrician. Check with the Electrical Workers Registration Board if you're unsure.
You can find a trusted local locksmith in your area through tradedirectory.co.nz.