Basic Fire Door Requirements

Basic Fire Door Requirements

Basic Fire Door Requirements

1      Introduction

Fire testing of doors and hardware and the resulting labeling authorities granted, is a com- plex subject that is better understood when basic rules and guidelines are applied.

2      Doors

The fire rating classification of the wall into which the door is installed dictates the required fire rating of the door. The location of the wall in the building and prevailing building code estab- lish the wall’s fire rating. The associated door ratings are shown in table 1 below.

2.1                     Hourly ratings

Steel fire doors are “rated” by time (in minutes or hours) that a door can withstand exposure

to fire test conditions. Hourly ratings include 1-1/2-hours, 1-hour, 3/4-hour, and 1/3-hour, with the maximum rating required of any swing- ing type fire door being three hours.

2.2                     Three-hour (180 minute) doors

A door with a three-hour fire protection rat- ing is usually found in walls that separate buildings or that divide a large building into smaller fire areas. The wall rating is four hours.

2.3                     1-1/2-hour (90 minute) doors

Doors rated for 1-1/2 hours are found in 2-hour rated walls. These doors are commonly lo- cated in stairwells, or other enclosures of ver- tical communication through a building. They also occur in boiler rooms and in exterior walls that have potential for severe fire exposure from the outside the building.

Table 1 – Fire door openings

OpeningWall RatingDoor and Frame RatingDescription and Use
  4 Hour3 Hour(180 minutes)These openings are in walls that separate buildings or divide a single building into designated fire areas.
  2 Hour1-1/2 Hour (90 minute)Openings of this type are used in enclosures of vertical communication or egress through buildings. Examples of these types of openings include stairwells and elevator shafts.
  1 Hour1 Hour(60 minute)These door and frame assemblies divide occupancies in a building.
  1 Hour3/4 Hour (45 minute)For use where there are openings in corridors or room parti- tions.
  2 Hour1-1/2 Hour (90 minute)This opening is in a wall where there is the potential for severe fire exposure from the exterior of the building.
  1 Hour3/4 Hour (45 minute)This opening is in an exterior wall that has the potential to be exposed to moderate to light fire from the exterior of the building.
  1 Hour1/3 Hour (20 minute)These openings are in corridors where smoke and draft control is required. The minimum wall rating is 1 hour.

1.1                     One-hour (60 minute) doors

One-hour rated doors are used in walls be- tween rooms, which are also typically one- hour rated.

1.2                     3/4-hour (45 minute) doors

Doors with 3/4-hour fire protection ratings are used in one-hour walls. A 3/4-hour rated door is found in walls of corridors and room parti- tions. A door with this rating may also be located in the exterior wall of a building sub- ject to moderate fire exposure from the out- side of the building.

1.3                     1/3-hour (20 minute) doors

One-third-hour or 20 minute doors are used in one-hour walls. These doors are used for cor- ridor applications and in other applications where smoke and draft control is a primary concern.

1.4                     Twenty-minute doors tested without hose stream

Doors and frames may also be rated as 20 minutes without a hose stream. These doors have successfully passed a 20-minute fire test, with the omission of the hose stream test, and bear a label that specifically states “Twenty- Minute-Rating Tested Without Hose Stream.” These doors may be provided with vision lights only limited in size by the door manufacturer’s fire labeling procedure authority.

Assemblies identified as “Twenty-Minute-Rat- ing Tested Without Hose Stream” should not be confused with 1/3-hour fire rated doors, which have been tested in accordance with the standard fire test procedure that includes the hose stream test.

1.5                     Summary

Doors are rated for three-fourths of the rating of the surrounding wall: A 3-hour door is used in a 4-hour rated wall; a 1-1/2-hour fire door is used in a 2-hour rated wall; and a 3/4-hour door is used in a one-hour rated wall. The notable exception is that 1/3-hour rated doors are also used with one-hour rated walls.

However, a door with a higher fire rating than the opening requires may also be used. For example, a door rated for 3 hours may  be used in a 1-1/2-hour opening. All requirements

for the 3 hour rating, such as maximum glass size, door size, and other restrictions for the higher rated door must be met.

2      Glass

1/4″ wire glass and ceramic glass are the most common types of glazing used in fire rated doors. The hourly rating of the door dictates the number and maximum size of the vision lights used in the door. Table 2 shows the limitations of size, area and number of vision lights in a door. Vision lights are not allowed in 3-hour rated fire doors, unless allowed by the local authority having jurisdiction. The vision light kit or window frame must be approved for use in a fire rated door.

3      Temperature rise doors

In certain applications, fire doors are required to minimize the transmission of heat from one side of the door to the other, as in the stairwell of a high rise building. If the door can limit the transmission of heat for a period of time, it is possible for people in a burning building to safely pass below the floor of fire origin. These doors are built with a specifically designed core and are referred to as temperature rise doors.

In addition to the hourly rating, the fire door label will also state the temperature rise rating of the door. Temperature rise ratings are 250°F, 450°F, and 650°F, and indicate the maximum rise in temperature above ambient temperature measured on the unexposed sur- face (non-fire side) of the door during the first 30 minutes of the standard fire test. The 250°F temperature rise designation is the most strin- gent rating of the three, since it requires the most limiting rise in temperature. A 250°F temperature rise door meets the requirements of specifications calling for a 450°F or 650°F temperature rise rating.

4      Louvers

Listed fusible-link type louvers to a maximum size of 24″ x 24″ are permitted in 1-1/2-hour


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Table 2 – Door glazing

1/4″ Wire Glass
Hourly RatingMaximum Exposed Area ( Sq. In.)Maximum WidthMaximum HeightNumber of Lights
20 min. w/o Hose299435-13/16″83-5/8″No Limit
20 and 45 Minutes129636″54″No Limit
20 and 45 Minutes*285634″84″No Limit
60 and 90 Minutes*220412″46″4
90 Minutes10012″33″No Limit
* Requires use of special Bedding Compound
Ceramic  Glass
Hourly RatingMaximum Exposed Area ( Sq. In.)Maximum WidthMaximum HeightNumber of Lights
20 min. w/o Hose283535″81″No Limit
20 and 45 Minutes129636″54″No Limit
60 Minutes129636″54″No Limit
90 Minutes129636″54″No Limit
180 Minutes10012″33″1

and 3/4-hour fire doors, with the louver mounted in the bottom half of the door. Lou- vers may not be used in 1/3-hour (20 minute) rated doors, or doors of other hourly ratings that may be part of a smoke and draft assem- bly. Doors with glass lights, or doors equipped with fire exit devices may not have louvers.

5      Fire door frames

Fire doors frames are not affected by the exposure ratings and opening classifications that apply to doors. There are no hourly rat- ings for a basic fire door frame unless the labeling on the frame specifically states that the frame is rated for something less than 3 hours. If a frame bears a recognized label qualifying it as a fire door frame, it may sup- port a 3-hour, a 1-1/2-hour, a 3/4-hour, or a 1/3-hour door. Frames used in masonry walls may be used with a maximum 3-hour fire door, while frames used in drywall walls are in- tended to be used with a maximum 1-1/2-hour fire door.

6      Transom and sidelight assemblies

Labeled frames are available with transom areas, sidelight areas, or a combination of both. The transom and sidelight areas can be furnished with listed panel assemblies or listed glass, depending on the desired hourly rating. Frames with solid transom panel and/or side panels may be used in openings rated up to and including 1-1/2-hour. Some manufactur- ers have the capability to provide frames with solid transom panels that have a 3-hour rat- ing. Frames with labeled glass transom lights and/or sidelights may be used with doors that have up to a one-hour rating. Examples of individual visible glass light areas are shown in table 3. Transom/sidelight frames may also have a rating of twenty minutes without a hose stream. The glass openings allowed are only limited by the individual manufacturer’s list- ing.

The overall size of transom and sidelight frames is limited to the maximum size that a manufacturer has successfully fire tested. Since the size may vary, it is important to


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consult the manufacturer when writing specifi- cations.

The label applied to transom sidelight assem- blies will state whether panels or glass are to be used in the frame. If the frame contains both panels and glass, the label for glass lights is used since it is the most limiting rating.

7      Fire window frames (borrowed light)

Fire window frames are labeled hollow metal glass light frames that are not attached to a door frame. Fire window frames with a maxi- mum 3/4-hour rating may be provided in ac- cordance with the manufacturer’s listing. Indi- vidual glass openings are not to exceed 1296 square inches; the dimension for  width or height shall not exceed 54 inches. Fire win- dow frames with a 20-minute rating tested

without a hose stream are limited in overall size and glass area only by a manufacturer’s individual fire test program. Fire window frames are typically used in corridor walls and may be provided for masonry or drywall construction. Consult the frame manufacturer as to the abil- ity to supply fire window frames for drywall walls. Fire window frames may be provided with wired glass not less than 1/4-inch thick, or glass as approved by the labeling agencies.

8      Fire door hardware

To understand fire door hardware, you must re- member that fire doors serve four main purposes:

1) To serve as a regular door at all times; 2) to provide ready egress during a fire; 3) to keep fire from spreading throughout the building; and 4) to protect life and property.

Table 3 – Fire window frame and transom/sidelight frame glazing

1/4″ Wire Glass
Hourly RatingMaximum Exposed Area ( Sq. In.)Maximum WidthMaximum HeightNumber of Lights
20 min. w/o Hose5268109-3/4″109-3/4″No Limit
20 and 45 Minutes129654″54″No Limit
20 and 45 Minutes*4704106″106″No Limit
* Requires use of special Bedding Compound
Ceramic Glass
Hourly RatingMaximum Exposed Area ( Sq. In.)Maximum WidthMaximum HeightNumber of Lights
20 min. w/o Hose332595″95″No Limit
20 and 45 Minutes332595″95″No Limit
60 Minutes272177″77″No Limit
Hourly RatingMaximum Exposed Area ( Sq. In.)Maximum WidthMaximum HeightNumber of Lights
90 Minutes1,2230448″48″No Limit
90 Minutes1,3460896″96″No Limit
180 Minutes1,3460896″48″No Limit
1 Check with individual manufacturer for specific panel size and construction2 1/2″ thick composite panel3 1-3/4″ thick hollow metal panel


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To adequately perform these functions, a fire door must be equipped with fire listed hard- ware for dependable operation. Proper hard- ware selections can be verified by consulting the current editions of “Building Materials Di- rectory” published by Underwriters Laborato- ries Inc., “Directory of Listed Products” pub- lished by Intertek Testing Services and “Hard- ware for Labeled Fire Doors” published by the Door and Hardware Institute. These manuals identify hardware and other products that may be used in fire-rated assemblies.

The National Fire Protection Association’s publication, NFPA 80, entitled, “Standard for Fire Doors and Fire Windows” provides guid- ance for installing fire doors and frames and hardware in the openings of a building.

8.1                     Hinges

A labeled fire door must be hung on steel bearing-type hinges. The use of steel is nec- essary since non-ferrous metals become “elastic” at much lower temperatures, which could allow serious dislocation of the door during a fire. There are certain hinge de- signs made of non-ferrous metals which may be used on fire doors in accordance with the listing information for the particular hinge. These hinges are usually used on doors of lesser fire rating.

The bearing type knuckles on hinges are re- quired in order to provide smooth operation and to minimize wear throughout the lifetime of the opening. Remember, a fire door must close in the event of a fire. Worn hinges will cause the door to sag, effectively preventing the door from closing. Exception: Some manufacturers may provide doors with hinges which are non-bearing type when they are part of a listing assembly.

NFPA 80 allows the use of standard weight (1.34 inches leaf thickness) 4-1/2″ hinges on 1-3/4-hour doors up to 4’0″ in width and 8’0″ in height. Doors over 8′ in height shall have heavy weight (.180 inches leaf thickness) 4-1/2″ hinges. Some manufacturers have the capability of providing lighter weight hinges on doors over 8′ in height as part of a listed assembly. (Consideration should be given to larger hinge sizes for heavy or frequent use doors.)

8.2                     Latching devices


may be provided in addition to the latch bolt, except on doors used as a means of egress, where interconnected locks may be used which retract the dead bolt with the  latch bolt. Dead bolts may not be used in place of latch bolts.

When selecting latching devices, it is impor- tant to use the correct length of latch bolt, a requirement that can vary with the door con- struction and the manufacturer’s fire testing program. It is common for a pair of doors to require a longer latch bolt throw than a single door. The minimum latch bolt length that must be used for any given door is indicated on the fire door label.

Some state and city building code authorities allow the use of a “push” and “pull” function on certain fire rated openings. This push/pull func- tion does not include a self-latching device and does not allow a fire door to perform its vital function. Without a latching device the door will not remain closed during a fire. A manufacturer cannot fire label a door pre- pared only for a push/pull function.

8.3                     Fire exit hardware

Exit devices may be used on labeled doors provided the door labeling specifically states “Fire Door To Be Used With Fire Exit Hard- ware.” This label indicates that the door has been properly reinforced for fire exit devices. Doors that bear this label must pass a panic loading test in addition to the standard fire test. The panic load test measures the struc- tural capability of the door to allow the hard- ware to operate in a panic situation.

Care must be taken when selecting exit de- vices for use on fire rated doors, as some devices have been tested for panic loading only, and not fire tested. In addition, exit de- vices have size and hourly rating restrictions, and must be properly labeled and identified as fire exit hardware.

8.4                     Closing devices

A properly sized closing device is the last of the “basic” fire door hardware requirements. A

fire door must be in a closed and latched position to serve as a protective barrier in the event of a fire. For this reason, either spring hinges or a listed door closer is required. When the door is closed, the closer has served its role as a protective device.

1.1                     Hold open devices

Mechanical hold-open devices and hold-open arms on door closers should be avoided. Fus- ible link equipped closers with a hold-open feature are available, but the fusible linkages will not function quickly enough to allow the door to act as a protective barrier to save human lives. Tests and investigations have proven that smoke and toxic gases are the main cause of death in tragic fires. Doors held open by electromagnetic release devices are the only ones which will close quickly enough to prevent the passage of the toxic gases and smoke. These devices are activated by elec- tronic detectors that sense smoke and/or the products of combustion.

2      Hardware — Pairs of doors

Pairs of doors for labeled openings have some unique hardware requirements because of the presence of the inactive leaf.

2.1                     Hinges and closing devices

Pairs of doors for labeled openings require steel, bearing-type hinges or a listed continu- ous hinge. Closing devices are required on both leaves of a pair of doors except on me- chanical equipment rooms where the closing device may be omitted from the inactive leaf,  if acceptable with the authority having juris- diction.

2.2                     Latching hardware

  • Active leaf of pairs of doors

The active leaf of a pair of doors may have either labeled fire-exit hardware, or any la- beled latch that shall be opened by one obvi- ous operation from the egress side.

2.2.2                                     Inactive leaf of pairs of doors

Where pairs of doors are being used as an entrance to an equipment room or similar situ- ation, manual flush or surface mounted bolts

may be used to secure the inactive leaf. Under these circumstances, the NFPA recommends that the inactive leaf have no knob or other visible hardware.

Labeled fire exit devices are mandatory for exits unless local authorities give specific ap- proval for the use of labeled self-unlatching and latching devices, such as automatic flush bolts on the inactive leaf. The self-unlatching feature must work only when the active leaf is opened.

2.3                     Double egress pairs

Double egress pairs of doors should only be provided with vertical rod fire-exit device hard- ware on both leaves. The vertical rod devices may be either surface mounted or concealed. Double egress doors and frames are part of a listed assembly and only those door designs that are named in a frame manufacturer’s published listing may be used.

2.4                     Astragals

Astragals may or may not be required on pairs of doors depending upon the individual door manufacturer’s labeling capabilities. Pairs of doors that do require an astragal shall have at least one that projects a minimum of 3/4-inch beyond the edge of the door to which the astragal is attached. Pairs of doors that are in a required means of egress may not be equipped with an astragal that inhibits the free use of either leaf. An astragal may not be used on pairs of doors with vertical rod exit devices on both leaves of the pair. Pairs of three hour doors always require an astragal per NFPA

  1. Other combinations of fire exit hardware on the active leaf and a vertical rod device on the inactive leaf are acceptable.

In some situations a coordinator may be needed to allow the inactive leaf to close ahead of the active leaf. This ensures proper latching of pairs of doors. Some manufactur- ers are able to supply labeled pairs of doors with an open-back strike without an astragal, which eliminates the need for a coordinator.

3      Label materials and attachment

There are several materials used for making fire labels that are acceptable to recognized


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labeling agencies. These include steel, brass, aluminum, and non-metallic. Metal labels are attached by welding, riveting, pop riveting or with drive screws. Non-metallic labels are ei- ther die-slit or tamper proof with an adhesive back. Once applied, if any attempt is made to remove the label it will tear apart indicating tampering. Embossed labels are label mark- ings which are stamped directly into the steel, and are also acceptable to the labeling agen- cies.

Fire labels on doors and frames are not in- tended to survive a fire to prove guilt after the fact. The label is there to indicate that the opening is protected by a properly constructed and applied steel door and frame. Adherence to fire protection requirements must be per- formed before a fire occurs.

4      Fire test methods

There are two primary fire test methods that are used to establish the fire ratings of doors. The first is UL 10B and is referred to as  neutral pressure; the second is UL 10C, and is referred to as positive pressure.

The difference between the two test methods concerns the location of a neutral pressure plane in the test furnace. In the late 1990’s, the test method required in building codes changed to a positive pressure test method. This change was adopted in the Uniform Build- ing Code (UBC) and the International Building Code (IBC) for swinging-type fire doors.

Fire doors required to be tested to either method may be specified by calling out the test method or by indicating that the product must meet a specific section of a model build- ing code.

5      Smoke and draft control

Doors that open onto corridors that are used for a means of egress may be required to have a smoke and draft control rating. Smoke and draft control assemblies are tested for both air leakage and fire resistance.

The assembly is tested to determine how much air leaks around the door. The assembly is

tested for air leakage with air that is at room temperature and air that has been heated to 400°F. The amount of air leakage must be below the standards that are set forth in the building code and/or NFPA 105.

An identical assembly is also subjected to a fire test. The unit must at least pass a 20- minute-without-hose-stream fire test to be qualified as a smoke and draft control assem- bly.

13.1   Gaskets

Gaskets are required for doors to pass a smoke and draft control test. The requirement for a gasket also includes the meeting edges of a pair of doors. The gaskets used in a smoke and draft control assembly must be fire rated and be listed for use in a smoke and draft control assembly. A bottom seal is not re- quired for smoke and draft control assemblies.

The UBC code calls for a tight fitting assembly that meets the requirements of UBC 7.2 Part II. The UBC includes the following statement: “Smoke and draft control door assemblies shall be provided with a gasket installed so as to provide a seal where the door meets the stop on both sides and across the top.”

13.2   Marking

The UBC requires Smoke and Draft Control assemblies to have an identification mark of “S” which appears on the label following the hourly rating.

6      References

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


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Suggested Procedure for the Selection of Swinging Fire Doors and Frames

  1. Determine the appropriate building
  2. Check and fulfill the fire insurance company’s requirements for the specific
  3. Basic Fire Door Requirements — Use this check
    1. A fire door must have a label
    2. A fire door frame must have either an attached or an embossed
    3. A fire door must be self-latching.
    4. A fire door must be self-closing.
    5. If a fire door is held open, it must be equipped with a listed heat responsive device, fusible link or a smoke detection
    6. A fire door must be free of any obstructions which could prevent the door from operating properly, e., wedge door stops, chains, hookbacks, etc.
    7. Only listed fire door hardware shall be
    8. A fire door must have steel bearing-type (Exception: Non-bearing plain steel hinges may be used if they are part of a listed assembly.)
    9. Doors swinging in pairs that require astragals shall have at least one overlapping Pairs of doors within a means of egress shall not be equipped with an astragal that inhibits the free use of either leaf. A coordinator or open-back strike should be used to ensure proper closing.
    10. Fire doors with glass lights:
      1. The glass frame and glazing bead must be
      2. The glass must be labeled wire glass not less than 1/4″ thick or as permitted by thelabeling
    11. Fire doors with fusible link louvers:
      1. Only listed louvers can be
      2. Louvers can be furnished in 1-3/4″ thick doors with a 1-1/2-hour or a 3/4-hour (no louverand glass light combinations are permitted).
      3. Maximum louver size is 24″ x 24″.
      4. Louvers are not permitted to be installed in doors with fire exit hardware or in
    12. For maximum fire protection, Standard Number 80 of the National Fire Protection Association should be used for an installation
    13. Purchase doors from a recognized, responsible manufacturer whose fire doors and frames are produced to conform to Fire Door Procedures and are subject to periodic

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