415 Riversdale Rd, Hawthorn East VIC 3123Call (03) 7033 0253

Deadlocks Explained: Single Cylinder, Double Cylinder and Night Latches

Lock names get used loosely in hardware aisles. Here is what the common types do in plain terms.

Night latch

Locks automatically when the door closes and opens from inside with a knob. Convenient, but the bolt is spring-loaded and offers less resistance than a deadbolt.

Single-cylinder deadlock

Key on the outside, thumbturn on the inside. The bolt is thrown solidly into the frame and cannot be pushed back. You can always exit quickly, which is why this is the safest default for most homes.

Double-cylinder deadlock

Key required on both sides. It stops an intruder reaching through broken glass to open the door, but it also means nobody leaves without a key. If you fit one, agree as a household exactly where the internal key lives.

What the frame is doing

A strong bolt in a weak frame is still weak. Long screws into the stud behind the jamb and a solid strike plate often add more real resistance than a more expensive lock.

This guide is general information, not advice about your specific property. If you want a recommendation for your doors, book a security assessment or call us.

Need a locksmith in Melbourne?

Tell us the door, the lock and the suburb. You will get a realistic price range on the phone and a fixed price in writing before any work begins.