Temperature-rise Metal Doors: Designed to delay and limit heat transfer generated from a fire. The cores demonstrate superior performance in protecting the areas that are not yet exposed to the fire by slowing the transmission of heat. These heat-retardant capabilities allow for safe evacuation during a fire. In accordance to temperature rise standards, the unexposed door surface will reach a maximum temperature of 250°F during the initial 30 minutes of a fire and 450°F after 60 minutes. Our standard fire rated metal doors are 1 ¾” thick and are available in 16, 18, and 20 gauge galvannealed steel.

General Specifications: Door faces are flush and free of any joints, welds or seams. Longitudinal door edges are interlocked with mechanical seam (seamless edge optional). Door hinge reinforcements are prepared for standard weight 41⁄2” x 41⁄2” hinges which can easily be converted to accommodate heavy weight hinges.

Direct Doors use fire labeled doors approved by both Intertek Testing Services (ITS Warnock Hersey) and Underwriters Laboratories (UL) Fire Labeling Programs. Doors can be fire labeled for up to 3 hours and must be installed in an equivalent fire labeled frame with approved fire listed hardware.


Mineral Core is an asbestos-free, mineral-based product that meets the criteria for 45, 60, and 90 minute fire rated doors. The manufacturing of the fire door core is accomplished with a proprietary process developed by the manufacturer. The premium core is unique in regard to weight and strength properties.

May be labeled and classified by Warnock Hersey International or Underwriters Laboratories as 45-60-90 minute rating. Doors are capable of meeting the requirements for both positive and neutral pressure fire tests, including UBC 7-2 (1997), UL 10C(1998), NFPA 252 (1995), ASTM E-152 (1982), and UL 10B (1997), including the hose stream. Restrictions on machining and architectural accessories or application are per the governing authority.

Agrifiber, a wheat or flax based core, can be constructed to meet the criteria for 45 and 60 minute fire rated doors. The Agrifiber core allows greater compliance with LEED based requirements and provides an option to mineral based products. Contact the factory for details.

* Fire labeled doors may not be refit in the field if already factory prefit sized. If not factory prefit for length, maximum field trim is 3/4" from the bottom only per NFPA-80, 1986, Fire Doors, Chapter 1-3.5

Fire Door Classified Openings
The location of fire-door openings in a structure determines their classification. These classifications are established by the length of exposure protection necessary for the potential fire hazard of the area. There are also restrictions on the amount of glass that is permitted to be in a fire-door opening. Please call us for additional information on allowable maximum glass. Listed below are the six opening classifications.

Class Door Rating Description and Use

  • A 3 Hour (180 Minutes) Openings separate buildings or divide a building into multiple fire areas *Only available for HM Steel Doors*
  • B 1 1/2 Hour (90 Minutes) Stairwells, elevator shafts, and other vertical/exit areas C 3/4 Hour (45 Minutes) Openings into corridors or room partitions
  • D 1 1/2 Hour (90 Minutes) Areas of potential severe fire exposure from the exterior E 3/4 Hour (45 Minutes) Areas of potential moderate fire exposure from the exterior
  • F 1/3 Hour (20 Minutes) Areas where smoke and draft control is required

Five Basic Requirements for a Fire Rated Opening