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What NFPA 80 (2012 Edition) Says About Door Gaps: Steel vs. Wood Doors

When it comes to life safety, every detail counts. One often underestimated aspect of fire safety is the size of the gaps around doors. The National Fire Protection Association (NFPA) has strict guidelines regarding door gaps, and it's crucial to understand these guidelines, especially when it comes to differentiating between steel and wood doors. In this blog post, we'll delve into what NFPA 80 (2012 Edition) says about door gaps, highlighting the separate requirements for steel and wood doors and why these details matter.

NFPA 80 (2012 Edition) Overview

NFPA 80 (2012 Edition) is the standard for fire doors and other opening protectives, and it provides comprehensive guidelines for the installation and maintenance of fire doors. It covers various aspects of fire doors, including materials, labeling, and, importantly for this discussion, door gaps.

Steel Doors: Specific Requirements

  1. Maximum Gap Sizes: For labeled steel fire doors, NFPA 80 (2012) specifies that the maximum gap between the door and the frame must not exceed 1/8 inch (3.2 mm) in the vertical plane when the door is in the closed position. This tight tolerance is critical for preventing the passage of smoke and flames.

  2. Positive Latching: Steel fire doors must have positive latching hardware. This ensures that the door remains tightly closed during a fire, further preventing the spread of smoke and fire.

  3. Intumescent Seals: Steel fire doors should be equipped with intumescent seals, which expand when exposed to heat, effectively closing any gaps that may have developed due to the fire's temperature.

Wood Doors: Specific Requirements

  1. Maximum Gap Sizes: NFPA 80 (2012) outlines slightly different requirements for wood doors. For labeled wood fire doors, the maximum allowable gap between the door and the frame is 1/8 inch (3.2 mm) at the top and hinge sides, and 3/8 inch (9.5 mm) at the bottom of the door. This variance at the bottom allows for some flexibility, considering the potential for warping or swelling of wood doors over time.

  2. Positive Latching: Similar to steel doors, wood fire doors must also have positive latching hardware to ensure they remain securely closed during a fire event.

  3. Intumescent Seals: While intumescent seals are not always required for wood doors, they are recommended as an added safety measure to help close any gaps that may develop during a fire.

Why It Matters

Properly adhering to NFPA 80 (2012 Edition) requirements for door gaps is essential for several reasons:

  1. Life Safety: Correctly sealed doors with minimal gaps can significantly improve life safety by preventing the spread of fire and smoke, allowing occupants more time to evacuate safely.

  2. Preserving Property: Adequate door gaps can help maintain the structural integrity of a building during a fire, potentially reducing property damage.

  3. Code Compliance: Adhering to NFPA 80 ensures compliance with local fire codes and regulations, helping building owners and managers avoid legal repercussions.


In the realm of fire safety, attention to detail can save lives and property. Door gaps may seem like a minor consideration, but they play a vital role in containing fires and protecting occupants. NFPA 80 (2012 Edition) provides specific guidelines for door gaps, recognizing the unique characteristics of steel and wood doors. By understanding and implementing these requirements, we can enhance life safety in buildings and ensure that every detail is in place to safeguard lives and property.

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