How Does a Deadbolt Work?

A deadbolt secures your door by extending a solid steel bolt deep into the door frame. Unlike a spring latch, it can’t simply be pushed back with a credit card or similar object. That’s why nearly every exterior residential door uses one.

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See inside a deadbolt

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What does a deadbolt actually do?

🔒 Locksmith Blueprint | Locks Made Simple: a deadbolt does much more than simply lock a door. It extends a solid bolt into the door frame, it’s stronger than a spring latch, and locksmiths use that knowledge every day.

• Bolt, not latch. A spring latch is beveled so the door can close on its own. A deadbolt’s bolt only moves when you turn the key or thumbturn, so it can’t be pushed back with a credit card or similar object.
• Into the frame. The bolt extends into the strike in the door frame.
• On almost every exterior door. That extra security is why nearly every exterior residential door uses a deadbolt.

Bill’s short look at everything a deadbolt is doing on your door. Watch on YouTube.

The parts that work together

• Key cylinder: decides whether the correct key can turn. See how a pin-tumbler lock works.
• Tailpiece: carries the turn from the cylinder or thumbturn to the bolt mechanism.
• Thumbturn: the inside control.
• Bolt and housing: the part that extends into the frame.
• Strike and frame: where the bolt lands. If the bolt rubs here, the lock feels stiff even when the cylinder is fine. That’s why a deadbolt that’s hard to turn is often a door-alignment problem.

Adding one to a door that doesn’t have one? Start with how to install a deadbolt.

Continue learning

• What Is Rekeying?
• How a Lock Works
• When Replacement Makes More Sense Than Rekeying
• Why Keys Stop Working
• Why Your Deadbolt Is Hard to Turn
• How Double French Doors Lock and Unlock
• Locksmith Tools for Beginners

Printable guides from Bill

Check every door, not just this one

These printable checklists help you look over the deadbolts, doors and entries in your home.

Every Door, Window & Key — Complete Home Security Bundle (9 Guides)Nine printable checklists for doors, windows, codes and keys, plus a Start Here guide.$12.99Get it →Often the Weakest Door — How to Secure Your Garage-to-House DoorA printable checklist for the door between your garage and your house.$4.99Get it →Free Lock-Check ChecklistName the symptom, identify the hardware and build a parts list before you buy.FreeOpen the free checklist →

Printable PDFs from Kwikpick Lock and Safe. Instant download, checkout by Gumroad. More for new homeowners on our new homeowner page.

Parts and tools for this problem

Start with the matching checks in Bill’s field guides. Buy only after you identify your hardware and the cause.

The correct spare key before a replacement lock

A known working spare can help separate key wear from a lock problem. Do not order a cylinder or spray a product into it based on resistance alone.

Compare worn-key symptoms →

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