What is a Door Shim?

A door shim is a thin, flexible tool used to bypass certain types of door latches by sliding between the door and the frame. It works by pushing the spring-loaded latch bolt back into the lock, allowing the door to open without using a key.

Door shims are commonly used by locksmiths during lockout situations when a door is closed but not secured with a deadbolt. Because the shim is thin and flexible, it can slide into the gap between the door and frame and retract the latch mechanism.

This technique is generally used for non-destructive entry, meaning the door and lock remain undamaged during the process.

How a door shim works

A door shim works by manipulating the latch bolt inside the door lock.

The typical process includes:

• The thin shim is inserted between the door and the frame

• The shim slides toward the latch bolt location

• Pressure is applied against the angled side of the latch

• The latch retracts into the lock mechanism

• The door can then be pushed open

This method works because most latch bolts have a beveled edge designed to compress when the door closes.

When locksmiths use a door shim

Door shims are typically used in specific lockout situations.

Common situations include:

• Interior door lockouts

• Doors secured only by a spring latch

• Residential door lockouts without a deadbolt

• Quick entry for maintenance or service situations

• Training demonstrations in locksmith education

However, this method is ineffective if the door is secured with a deadbolt or if additional security plates block the latch.

Types of door shims

Door shims can be made from different materials depending on their intended use.

Common types include:

• Plastic door shims – flexible and safe for most doors

• Metal door shims – thinner and more durable for professional locksmith use

• Improvised shims – sometimes made from thin plastic sheets or cards

Professional locksmith tools are usually designed to be strong enough to manipulate the latch while remaining thin enough to fit into tight gaps.

Limitations of a door shim

While door shims can be effective, they only work under certain conditions.

Limitations include:

• Cannot bypass deadbolts

• Ineffective on doors with latch guards or security plates

• Limited use on tightly sealed modern doors

• May not work on high-security latch designs

Because of these limitations, locksmiths often combine shims with other professional entry tools.

Advantages of using a door shim

Door shims offer several practical benefits for locksmiths and maintenance professionals.

Main advantages:

• Allows fast non-destructive entry

• Simple and inexpensive tool

• Lightweight and easy to carry

• Useful for basic latch lockouts

• Requires minimal equipment

Although modern security hardware may reduce its effectiveness, the door shim remains a useful tool for certain types of lockout situations.

A door shim is a simple but effective locksmith tool used to bypass spring-latch locks in specific situations. By retracting the latch without damaging the lock, it provides a quick solution for certain types of door lockouts.

Door Shim Overview