Single vs. double cylinder
A single-cylinder deadbolt turns with a thumbturn inside — the right choice for most doors, and the safe choice anywhere it’s the exit in a fire. A double-cylinder needs a key on both sides; it exists for doors with glass an arm’s reach from the lock, where a broken pane would otherwise let someone turn the thumbturn.
Double-cylinder comes with a real trade-off: you must be able to find that key in an emergency. Many fire codes restrict them on required exits. We’ll walk your specific door and recommend honestly.
The strike is half the lock
A deadbolt throwing into a shallow strike plate with short screws is decoration. A proper installation uses long screws that reach the door frame’s stud and a strike box that gives the bolt something real to hold. When we install a deadbolt, the strike work is included — it’s where the strength actually is.
Grades matter the same way: an ANSI Grade 1 or 2 deadbolt on the main entry, properly struck, outperforms a premium lock on a weak frame every time.
Where deadbolts belong
Front and back doors first, then the door from the garage into the house — the one everyone forgets and burglars don’t. Sliding doors need a different answer entirely; see sliding door locks.
How this article connects
- ✓Lock Repair & Installation
- ✓Residential Locksmith — the full service page
- ✓High-Security Locks
- ✓Rekey vs. Replace
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