Why deadbolt locks matter for home security

A spring latch, the slanted bolt in most doorknobs, holds a door closed. A deadbolt locks it. That difference is why nearly every security guide starts with the deadbolt.

How a deadbolt works

A deadbolt's bolt is square-ended and can't be pushed back by force on the bolt itself. It only moves when the key or thumb-turn moves it. Most extend about an inch into the frame, which makes the door much harder to force open.

Types of deadbolt

• Single cylinder – key outside, thumb-turn inside. The most common choice.
• Double cylinder – key on both sides. Useful near glass, but it can slow your exit in a fire; check local fire rules before choosing it.
• Keypad and smart deadbolts – a code or phone instead of a key, often with a key override.

ANSI grades

Deadbolts are graded by ANSI/BHMA. Grade 1 is the heaviest duty and is the usual recommendation for front doors and doors from the garage. Grade 2 is common in homes. Grade 3 is the lightest.

The upgrade most homes need

A strong deadbolt is only as good as what it locks into. Many strike plates are held by short screws into soft trim. Replacing them with a reinforced strike and long screws that reach the wall framing is one of the most cost-effective security upgrades you can make.

Installation

Doors without a deadbolt need a bore hole and a strike pocket. The price list shows new lock installation on a door without a hole starting at $85, and lock changes for basic locks from $25. New locks carry a 3-month warranty from the contractor. See the residential locksmith page.