What Is the Difference Between a Single Cylinder & a Double Cylinder Deadbolt Lock?

Using deadbolt locks is one way to help secure your home against intruders. Regular locks can be picked, jimmied or hammered to gain entrance but quality locks often deter burglars.

Not all locks are the same.


Deadbolt locks are made to withstand amateur attempts at illegal entry. Typically the outer casing is made from hardened steel and resilient against hammer blows. Twisting these locks loose with pliers or a pipe wrench is no easy task either.


The single cylinder deadbolt is the most common. It is found on front or back exterior doors and requires a key to open it from outside. A thumb turn opens it from the inside. A double cylinder deadbolt has no thumb turn. This prevents intruders from entering and exiting easily


Not all deadbolts meet the Builders Hardware Manufacturers Association (BHMA) standards. "To assure you are getting the performance you specify. Look for the mark of Certification. Insurance companies recommend using single and double cylinder deadbolts that meet the ANSI Grade 1 specification.


The double cylinder lock requires a key to enter or exit. This can prove hazardous in emergency situations. A missing key could be responsible for trapping someone inside.


Deadbolts with a captured key feature operate like a single and double cylinder lock. The interior thumb turn can be removed to create a keyhole. The last person out the house creates a double cylinder lock by removing the thumb-turn.