US fire door requirements, explained for suppliers.

1. A fire door is an assembly

This is the main difference to how many shops think about doors: the inspector does not approve a door, they approve an opening.

• Door leaf, frame, hinges or pivots, latch, closer, gasketing, edge seals and glazing are tested together and listed together.
• Each component carries its own label or listing: the door, the frame, the glazing and the fire-rated hardware.
• Replacing one part with an unlisted part, for example a non-rated lever or a residential hinge, takes the whole opening out of compliance.

2. Test standards

• UL 10C / NFPA 252, positive pressure: required by the IBC for side-hinged and pivoted swinging fire doors. The neutral pressure plane sits about 40 inches above the floor, so fire pushes against the upper part of the door and its edges.
• Edge seals: to pass positive pressure, wood doors need intumescent edge seals, either built into the door edge (Category A) or applied to the frame or door (Category B), as named in the listing.
• UL 10B: neutral-pressure test, still used for sliding doors and other non-swinging assemblies.
• UL 1784: air leakage test for smoke and draft control. Maximum 3.0 cfm per square foot of opening at 0.10 inch of water, at room and elevated temperature.
• 20-minute corridor doors are tested without the hose stream; higher ratings include it.

3. Which rating where

The door rating follows the wall. A summary of IBC Table 716.1(2):

4. Labels

• Labels are permanent, metal or approved material, applied at the factory, usually on the hinge edge of a wood door.
• They show the listing lab mark (for example UL or Warnock Hersey), the rating in minutes, a traceable manufacturer code and a serial or listing number.
• Doors in interior exit stairways and exit passageways also need a temperature-rise rating: at most 450 °F above ambient after 30 minutes, unless an exception for sprinklered buildings applies.
• Only the listing lab can field-label a door. A door that arrives without a label cannot simply be labeled on site.
• Do not paint over labels. Painted, removed or unreadable labels are among the most common inspection failures.

5. Glazing in fire doors

• Fire-rated glass carries its own marking: D for door, H for hose stream, T for temperature rise, W for fire-resistance, and the minutes.
• 20-minute doors: glazing marked D-20, up to the maximum size tested.
• 60 and 90-minute doors in exit enclosures and shafts: fire-protective glass is limited to 100 square inches; larger lites need fire-resistive glazing marked D-H-T or D-H-W.
• Glass, glazing beads and lite kits must all be listed for the door. A vision panel cut in the field voids the label.

6. Hardware

• Fire doors must be self-closing (or automatic-closing on alarm) and positive-latching.
• Hinges, locks, exit devices and closers must be listed for fire doors. Exit devices on fire doors are labeled as fire exit hardware.
• Hold-open devices such as kick-down stops or wedges are not allowed. Magnetic hold-opens must release on fire alarm.
• Pairs need a coordinator and astragal where the listing requires them; the inactive leaf usually needs automatic flush bolts.
• Factory machining from a hardware template keeps the label valid. Order the hardware schedule first, then the doors.

7. Installation, clearances and field work (NFPA 80)

• Clearances are limited: typically 1/8 inch at the head, jambs and meeting stiles of wood doors, and a limited gap at the bottom (commonly 3/4 inch). Check the edition and the listing.
• Allowed in the field: mortise lock and function holes, holes for labeled viewers, round holes up to 1 inch for surface-applied hardware, and limited bottom trimming where the listing allows.
• Anything else, such as new lites, louvers, larger cutouts or re-sizing, needs approval from the listing lab or makes the door unlabeled.
• After installation an acceptance test is required; after that, every fire door is inspected at least once a year with a written record.

8. Smoke and draft control

• Corridor doors and doors in smoke barriers and smoke partitions often need an S-label (UL 1784) and must be installed per NFPA 105.
• The S-label assumes the listed gasketing is installed. Standard weatherstripping does not count.
• Louvers are not allowed in smoke doors.

9. Accessibility (2010 ADA Standards)

• Clear opening of at least 32 inches with the door at 90 degrees: in practice a 36-inch door.
• Hardware operable without tight grasping or twisting, mounted 34 to 48 inches above the floor: lever handles, not knobs.
• The 5 lbf opening force limit does not apply to fire doors; they need the minimum force the AHJ allows to close and latch reliably.
• Closers: at least 5 seconds from 90 to 12 degrees. A smooth surface 10 inches high on the push side of the door bottom.

10. Materials and imports

• Wood doors containing hardwood plywood, MDF or particleboard fall under EPA TSCA Title VI (formaldehyde). Each door or box needs a label with fabricator, month and year of production and a TSCA Title VI compliance statement.
• The importer of record files a TSCA import certification. Panels used in the doors must come from a certified panel producer.
• Common US quality standards for flush wood doors are WDMA I.S.1A and the AWI/AWMAC/WI Architectural Woodwork Standards (AWS), with grades and duty levels named in the spec.
• Canada: doors tested to CAN/ULC-S104; 20-minute wood core doors to CAN/ULC-S113, under the National Building Code and provincial codes.