What is a deadbolt?

A deadbolt is a mechanical lock that operates through a rigid metal bolt, typically cylindrical or square, which slides horizontally into a strike plate on the door frame. Unlike a spring latch, the bolt has no spring mechanism to retract it automatically; instead, it locks in place until manually released by key rotation or thumb turn. This design makes deadbolts significantly harder to force open through pressure or shimming.

Deadbolts come in two main cylinder types. A single cylinder deadbolt has a key slot on the outside and a thumb turn on the inside, allowing occupants to lock or unlock from within without a key. A double cylinder deadbolt requires a key on both sides, which tightens security in high-risk areas but can pose an emergency exit hazard if the key is lost or forgotten. Building codes and insurance requirements in Singapore often specify which type is suitable for different premises.

The security advantage over spring latches lies in the bolt's resistance to prying and pressure. A spring latch can be pushed back by flexing the door or using thin tools, whereas a deadbolt's solid engagement with the strike plate resists such techniques. This is why deadbolts are the standard requirement for external doors in residential and commercial properties across the island. Residential locksmiths install and maintain deadbolts as core components of door security systems.