Why Metal Door Hinge Shims Are Essential for Fire Door Safety

In fire-rated door assemblies, even a minor misalignment can mean a failed inspection or compromised safety. That’s why metal door hinge shims matter. Unlike plastic or wood alternatives, only metal shims meet the NFPA 80 requirement for maintaining critical clearances under fire conditions. If you’re installing or adjusting a commercial or fire-rated door, using the right shim isn’t optional—it’s essential.

But What Is a Metal Door Hinge Shim?

A metal door hinge shim is a thin, steel plate used to adjust the alignment and clearance of fire-rated doors during installation. Unlike plastic or wood shims, metal versions are fire-resistant and structurally sound—qualities critical to meeting NFPA 80 fire door requirements.

Take a look at the commercial metal door shim here.

Why Does Metal Shim, and only ‘Metal’ Shim, Matter

When the frame is not perfectly square, the door may not sit correctly, which results in uneven gaps along the edges. If the hinges are misaligned or hardware is replaced without checking the alignment, it can further lead to inconsistent spacing.

Improper door clearances can cause major compliance problems, such as:

• Failed fire inspections
• Compromised fire barriers
• Doors shifting or malfunctioning
• Increased risk to life and property during a fire.

Additionally, to comply with NFPA 80, only metal materials are permitted for shimming fire-rated doors. This ensures the shim can withstand high temperatures and maintain proper clearances. NFPA 80 requires metal door shims because they are durable enough to support the door’s performance during a fire—something wood or plastic cannot guarantee.

Go further with more information on metal door shim on fire safety here.

How Metal Door Hinge Shim Solves the Problem

A metal door shim solves the problem of improper door clearance by providing precise alignment between the door and the frame. When frames are out of square or hinges are not perfectly aligned, gaps can become too wide or too tight, leading to fire code violations and operational issues.

Here is How to Shim Your Door Hinge

Step 1: Inspect door clearance
Close the door and look for uneven gaps along the top, sides, and bottom. Measure them to see if they meet NFPA 80 – 4.8.4 Clearance standards:

• Top and sides: max 1/8 inch (3.18 mm)
• Bottom (to floor or threshold): max 3/4 inch (19 mm)
• Bottom (if >38″ above floor): max 3/8 inch (9.5 mm)

Step 2: Loosen the hinge
Use a screwdriver to slightly loosen the screws on the hinge where adjustment is needed—usually the top or bottom hinge.

Step 3: Insert a metal door shim
Slide a thin steel shim behind the hinge leaf, either at the door side or the frame side, depending on the direction you need to shift the door.

Step 4: Re-tighten the hinge
Tighten the screws back securely to hold the shim in place.

Step 5: Check door operation
Open and close the door to ensure it moves smoothly and latches properly without rubbing or sticking.

Step 6: Recheck clearances
Measure again to confirm that the top and side gaps are around 1/8 inch, and the bottom gap is no more than 3/4 inch, per NFPA 80.

Double Tape Stainless Steel Metal Door Hinge Shim

Waterson metal door hinge shims are designed to deliver durability, precise alignment, and safety standards. This ensures compliance-ready alignment and long-term durability you can rely on in critical applications.

Additionally, the metal shim’s double sided tape design is fully removable and repositionable, stacked to increase thickness when needed.This adhesive backing holds the shim securely in place during installation, allowing for hands-free alignment while you adjust and tighten the hinge.

Waterson Metal Door Hinge Shims in Action

A client from Isenhour Door Product approached Waterson for steel door shims compliant with fire-rated standards. Impressed by the quality of Waterson’s hinges and shims, they couldn’t find a comparable product elsewhere. After some research, they referred to Waterson’s products and ended up with 1000 door shims. The feedback has been overwhelmingly positive since the shim’s design was so convenient to install.

Ready to align your doors to code and beyond? Choose Waterson Metal Door Shim for precision and peace of mind.

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Please note that Waterson closer hinges start from a size of 4″x4″. If you’re in need of smaller self-closing hinges, we’d recommend checking out some other resources! Also, we only provide single acting closer hinges. Thank you.

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