Why the installation matters as much as the lock
A deadbolt is only as strong as the door, frame and strike it's installed in. Many forced entries succeed not by defeating the lock but by kicking the door until the frame splits around the strike plate. A good installation reinforces those weak points.
Types of deadbolts
- Single-cylinder deadbolts have a key on the outside and a thumb turn inside. They're the most common choice for homes.
- Double-cylinder deadbolts need a key on both sides. They prevent someone from reaching through a nearby window to turn the thumb turn, but they can be dangerous in a fire if the key isn't immediately available, and some local codes restrict them. Ask the locksmith what's allowed in your area and consider the safety trade-off carefully.
- Smart and keypad deadbolts let you lock and unlock with a code, phone or fob, and some let you grant temporary access or see a log of entries. Most still have a key backup. Battery life, the security of the app and how the lock behaves if the batteries die are worth asking about.
Grades and ratings
Locks are commonly graded under industry standards that test durability and resistance to force. Higher grades have passed more demanding tests. Ask the locksmith which grade a lock carries and what that means in practice.
Reinforcing the door
- Strike plates with long screws. A heavy-duty strike plate fastened with long screws that reach the wall framing behind the door jamb, not just the jamb itself, makes the door far harder to kick in.
- Hinge screws. Replacing at least one short screw in each hinge with a longer one that reaches the framing strengthens the hinge side.
- Door and frame reinforcement kits add metal plates around the lock and along the jamb.
- Solid doors. Hollow-core doors are weak no matter what lock is installed. Exterior doors should be solid wood, solid-core, steel or fiberglass.
- Bolt throw. The bolt should extend fully into the strike; a typical residential deadbolt throws about an inch.
Doors with glass
Doors with glass panels or sidelights next to the lock are vulnerable to someone breaking the glass and reaching in. Options include security film on the glass, moving the lock, or, where allowed, a double-cylinder deadbolt.
What a complete installation includes
1. Checking the door and frame condition and how the door closes. 2. Drilling or adapting the bore and edge holes as needed. 3. Installing the deadbolt and a reinforced strike with long screws into the framing. 4. Adjusting the strike so the bolt throws fully and smoothly. 5. Testing the lock from both sides, and keying it to your other locks if you want. 6. For smart locks, setting up codes and the app with you.
Questions to ask
- What grade is the lock, and why do you recommend it?
- Will you install a reinforced strike with long screws into the framing?
- Is my door solid enough, or does it need reinforcement?
- Can this lock be keyed to match my other locks?
- For smart locks, what happens if the batteries die or the app stops working?
Sliding and French doors
Sliding patio doors and French doors have their own weak points. Sliding doors can sometimes be lifted off their tracks; anti-lift blocks or screws in the upper track and a secondary lock or bar help. French doors need strong flush bolts at the top and bottom of the inactive door, because a deadbolt alone holds only as well as that second door does.