Fire rated doors are required in numerous areas of a commercial buildings. Metal fire doors can attain ratings up to 3 hours where wood fire doors can be rated up to 90 minutes. Not all doors in a commercial building need to be fire rated. Fire rated door requirements are typically determined by the fire rating of the wall and use of the door.
A 3 hour door (180 min.) is typically required in 4 hour rated walls that separate buildings or divide a building into separate fire rated areas.
90 Minute doors (1-1/2 hr.) are required in 2 hour rated wall openings to stairwells, elevator rooms or egress through a building. 90 minute doors are also used in exterior openings where there is a potential for severe fire exposure from outside.
1 hour, or 60 minute assemblies are required on 1 hour rated walls that divide occupancies in a building.
45 Minute, or ¾ hour fire rated doors are installed in 1 hour walls that act as room partitions or divide corridors. 45 minute doors are also used in exterior door openings where there is a possibility of light to moderate fire exposure from outside.
20 minute fire doors, or 1/3 hour doors are used in 1 hour rated walls to separate corridors where smoke and draft control are required. In residential applications most doors separating the garage from the living quarters require a 20 minute label.
A door assembly must comply with the proper door hardware requirements to be approved as a rated assembly. Door hardware must be fire listed and comply with The National Fire Protection Association’s NFPA80 “Standard for Fire Doors and Fire Windows.”
Hinges: A fire rated door must be hung on ball bearing type hinges made from steel or another non-ferrous metal. Doors up to 4’0” wide and 8’0” tall can use standard weight (.134 thickness) ball bearing hinges. Doors over 4’0” wide and 8’0” tall must use heavyweight hinges. (.180 thickness)
Latches & Locks: All fire rated doors must include an automatic latching mechanism. These doors must stay closed in the event of a fire. Automatic latching mechanisms can include door knobs, lever handles, and push bar exit devices as long as the hardware is fire listed. Deadbolts do not constitute a latch since they do not automatically engage the strike. When using a deadbolt in a fire rated exit that is a means of egress the deadbolt must be an interconnected type or a function of a mortise lock where the deadbolt can be retracted automatically when the latch bolt is disengaged. Push and pull hardware does not automatically latch and therefore cannot be used in fire rated applications. A door manufacturer cannot label a push / pull assembly as fire rated. Fire rated double doors require a listed flush bolt on the inactive leaf or fire vertical exit devices on both leaves.
Closers: Fire rated doors must be self-closing. Either a listed spring hinge or closer is required at all fire rated openings.
Hold Open Devices: Mechanical or manual hold open devices are not permitted for use in rated assemblies. Restricting a door from closing negates its ability to perform as a protective barrier. Electromagnetic door holders that release the door in the presence or smoke fire are the only hold open devices permitted to hold the door opened.
Gaskets & Seals: Smoke gaskets must meet smoke and draft control requirements. The gaskets must be fire listed and approved for use in a smoke and draft control assembly. A door sweep or bottom seal is not a required. A gasket is required to provide a seal where the door meets the stop at the top and on both sides. Meeting edge gaskets are required between 2 leaves of a pair.
NFPA 80-1999 “Standard for Fire Doors and Fire Windows”
NFPA 252-1995 “Standard Methods of Fire Tests of Door Assemblies”
Underwriters Laboratories Standard for Safety UL 10B “Fire Tests of Door Assemblies”
Underwriters Laboratories Standard for Safety UL 10C “Positive Pressure Fire Tests of Door Assemblies”
Uniform Building Code Standard 7-2 “Fire Tests of Door Assemblies.”
International Building Code 2000
Steel Door Institute SDI 118-2001 “Basic Fire Door Requirements”