Scope

• Edition noted: NFPA 80, 2025; the IBC edition in force references an earlier edition until a code adopting 2025 applies. Always verify the adopted code edition and local amendments for the project jurisdiction
• Covers installation, field modification, inspection, and maintenance of fire doors, frames, hardware, and related protectives; the ratings of the doors come from the IBC and the door labels
• Door tests (NFPA 252 and UL 10C) and the required rating by wall type are in the openings and penetrations note
• This note gives clearances from a secondary source citing the 2022 edition; the standard itself is not reproduced

Terminology

• Fire door assembly: the door, frame, hardware, and closing devices that together carry a fire rating
• Label: the permanent mark from a testing lab showing the rating of a door or frame
• Label service: a manufacturer or authorized shop program that allows factory-controlled modifications
• Clearance: the gap between the door and its frame or floor
• Meeting stiles: the edges where a pair of doors meet
• Undercut: shortening the bottom of a door in the field
• Positive pressure test: the fire test (NFPA 252 or UL 10C) used for swinging doors
• Active latch bolt: the latch that holds a fire door closed
• Vision light kit: a labeled glass and frame kit installed in a door
• Annual inspection: the periodic check of fire doors required by the standard

Requirements

Clearances

• NFPA 80 (2022 edition), clearances: measured on the pull side of the door
  • Head, jambs, and meeting stiles of pairs: hollow metal doors 1/8 in. plus or minus 1/16 in. maximum; wood doors rated more than 1/3 hour 1/8 in. maximum; wood doors of 1/3 hour or less, and stile-and-rail wood doors in hollow metal frames, 1/8 in. plus or minus 1/16 in.
  • Other door materials: 1/8 in. maximum unless the door, frame, and latching hardware listings permit otherwise
  • Bottom clearance: 3/4 in. maximum from the bottom of the door to the top of the finished floor or threshold
  • Doors with the bottom more than 38 in. above the floor, such as access doors: 3/8 in. maximum, or as the label service procedure specifies
  • Projecting hardware latches: per the hardware manufacturer's instructions, not exceeding 3/4 in.
  • Thresholds: per the hardware manufacturer's installation instructions and listings

Field modification and glazing

• Field modifications are limited and need the permission of the listing laboratory; field labeling is subject to strict limits
• Wood and composite doors may be undercut in the field a maximum of 3/4 in., after checking with the manufacturer
• NFPA 80 (2025 edition), Section 4.4.4.4: labeled metal vision light kits may be field installed in new wood doors following the manufacturer's instructions; the cutout is still made at the factory or an authorized shop under label service; the change applies only when a code adopting the 2025 edition is in force
• NFPA 80 (2010 through 2022 editions): glazing in the vision panels of new wood doors is installed in labeled glass light kits or per the listing, under label service

Inspection

• Chapter 5 of NFPA 80 sets the criteria for inspecting and testing fire door assemblies; the interval and records are set by the standard and the AHJ

Where the IBC requires it

• IBC 2024, Section 716.1: opening protectives follow the section and are installed per NFPA 80
• IBC 2024, Section 716.2.6.4: automatic-closing assemblies are self-closing per NFPA 80

Worked examples

Clearance check on a hollow metal pair

A pair of hollow metal doors in a 1-hour wall.

Wood door undercut

A 1-1/2 hour wood door is too long for a thick carpet.

Vision light in a new wood door

Coordination

• Hardware schedule: hinges, closers, latches, and threshold items listed for the door and frame; avoid substitutions
• Frames and walls: frame anchorage and grouting follow the label and the wall assembly
• Finishes: floor finishes at the door change the measured bottom clearance
• Glazing: vision lights in fire doors are labeled kits or rated glazing; sizes are limited by the building code
• Smoke and fire alarm: magnetic holders release on alarm
• Owner: annual inspection and a maintenance plan after occupancy
• Contractor: field changes (cutting, drilling, reinforcing) go through the label service

Common issues

• Excess gap: worn hinges and wrong frames open the gap past the limit
• Field cut doors: cutting for hardware or glass outside label service voids the label
• Wrong hardware: unlisted latches and closers installed after approval
• Doors propped open: wedges and unlisted holders
• Floor build-up: floor finishes added after the door is hung
• Pairs: meeting stile gaps and astragals not matching the label

Standards

• NFPA 80: fire doors and other opening protectives
• NFPA 252 and UL 10C: fire tests of door assemblies
• UL 10B: fire tests of door assemblies, neutral pressure
• UL 1784: air leakage of doors for smoke and draft control

Sources

• I Dig Hardware: decoded, allowable clearances for fire door assemblies, https://idighardware.com/2022/07/decoded-allowable-clearances-for-fire-door-assemblies/
• I Dig Hardware: glazing in wood fire doors under NFPA 80-2025, https://idighardware.com/2025/05/qq-glazing-in-wood-fire-doors/
• GoCodebook: 2025 California Building Code, Section 716 opening protectives (based on the 2024 IBC), https://gocodebook.com/library/us/ca/ca-building-code/chapter-7-fire-and-smoke-protection-features/section-716-opening-protectives
• Image: Fire door label.jpg, Ben Schumin, CC BY-SA 3.0, https://commons.wikimedia.org/wiki/File:Fire_door_label.jpg