Everything To Know About Fire Doors

By enabling safe exit and compartmentalizing smoke, flames, and, where necessary, harmful radiant heat, fire-rated door assemblies play a crucial role in saving lives and limiting property damage. This is when the door, frame, hardware, and glazing all operate together as a single unit. These components are usually evaluated individually by a nationally recognized testing body before being listed, labeled, or categorized for use in fire door assemblies. However, in other cases, specific components are tested together and must thus be used together to preserve the fire rating.

NFPA 252, Standard Methods of Fire Doors Tests of Door Assemblies, or UL 10 B, Standard for Fire Tests of Door Assemblies, or UL 10 C, Standard for Positive Pressure Fire Tests of Door Assemblies are used to test fire door assemblies. The fire endurance test and the hose stream test are both performed on fire door assemblies, just as they are on fire window assemblies. It’s worth noting that in most parts of the United States, 20-minute doors are excluded from the hose stream test.

The following are the essential standards for fire-rated door assemblies:

  • Third-party testing agencies award fire ratings (20/45/60/90/180 minutes), which are labeled on the products.
  • The applicable building or life safety code, such as the National Fire Protection Association (NFPA) 80: Standard for Fire Doors and Other Opening Protectives, or the National Fire Protection Association (NFPA) 101: Standard for Fire Doors and Other Opening Protectives, must be met by fire rated door assemblies.
  • The International Life Safety Code (ILSC), the International Building Code (IBC), and the International Fire Code (IFC)
  • The Fire Code (IFC).
  • Self-closing and positive latching fire doors are necessary.
  • The door’s fire rating is determined by the wall’s fire rating.

Testing and Standards

The following standards are used to evaluate fire-rated doors:

  • Fire Tests of Door Assemblies, UL 10B (neutral or negative pressure)
  • Positive Fire Pressure Tests of Door Assemblies (UL 10C)
  • Standard Methods of Fire Tests of Door Assemblies (NFPA 252)

To more accurately imitate the conditions of a fire in the actual world, the mandatory test method was modified from neutral or negative pressure to positive pressure in the late 1990s. The IBC now requires positive pressure testing of side-hinged or swinging fire doors, utilizing either UL 10C or NFPA 252.

Endurance in the Fire

Fire-rated doors are put through endurance testing, which involves exposing the specimen to intense heat of up to 1925 degrees Fahrenheit for up to 180 minutes. The door is approved with an endurance grade of either 20/45/60/90/180 minutes if it remains in the frame with no through openings and limits flames.

Stream from a hose

Following the fire endurance test, the test specimen is put through a hose stream test, which involves a fire hose delivering water at 30 psi from a distance of 20 feet. It’s worth noting that 20-minute doors are often exempt from the hose stream test in most US building codes.

Temperatures are rising.

Fire doors are also necessary in some applications to prevent the passage of heat from one side to the other in order to protect building occupants and allow them to safely evacuate the building. These doors, also known as temperature rise doors, have a temperature rise rating in addition to an hourly rating. The highest rise over ambient temperature on the non-fire side measured during the first 30 minutes of a conventional fire endurance test is indicated by temperature rise ratings of 250 degrees F, 450 degrees F, or 650 degrees F. A temperature rise rating of 250 degrees Fahrenheit is regarded the most rigorous, and would meet the criteria of a specification requiring 450 or 650 degrees Fahrenheit.

Controlling Smoke and Drafts

Some fire-rated doors, such as 20-minute doors in fire-resistant corridors or smoke barriers, may also require smoke infiltration testing in accordance with UL 1784, Standard for Air Leakage Tests of Door Assemblies and Other Opening Protectives.

Glazing for Fire-Resistant Doors

Glazing is commonly used in today’s fire-rated doors to provide view and transparency, maximizing natural or shared lighting while also adding security to regions that would otherwise be closed off. Large vision panes in fire doors can give important safety benefits. First responders can see inside a room and assess the situation visually during a fire, allowing them to be more effective.

However, the glazing used in fire-rated doors often has additional fire and safety regulations, which can be perplexing. The International Code Committee (ICC) has worked to clear up this ambiguity throughout the years by including explicit rules in the building code.

Impact Protection

Traditional wired glass was the only fire-rated glass available for well over a century, and it was commonly employed in fire doors in schools, hospitals, and commercial architecture in general. Because the imbedded wires gave the appearance of improved strength and impact resistance, it was wrongly referred to as “safety glazing.” Wire actually weakens the glass, reducing its strength to half that of regular window glass. On human impact, it quickly breaks, exposing razor-sharp wires that can trap a victim’s limb in the aperture and worsen the injuries.

The Consumer Product Safety Commission (CPSC) enacted a federal safety glazing standard (16 CFR 1201) in 1997 to safeguard individuals from being injured by glazing. The CPSC standard is utilized in building codes to ensure that glazing used in hazardous areas, such as doors and sidelites, fulfill minimum Category I and II impact levels, depending on the size of the glazing panel. Smaller glazing panels with a surface area of up to 1,296 square inches must pass the 150 ft. lbs. Category I impact test. Larger glass panels must pass the higher Category II impact test, which requires impact resistance of 400 ft. lbs.

Traditional wired glass was given a temporary exemption from fulfilling the new CPSC rules when they were introduced, which meant it just had to meet the less stringent ANSI Z97.1 standard, which only required a 100 ft. lbs. impact test. Independent tests on typical wired glass, on the other hand, revealed that it can break with as little as 50 ft. lbs., a force easily generated by a five-year-old pressing on it.

This all changed in the 2003 International Building Code, when traditional wired glass was no longer excluded from satisfying safety glazing standards in educational and sporting buildings. Traditional wired glass is no longer exempt when used in any hazardous site for all new buildings and in all types of occupancies, according to the 2004 IBC Supplement and the 2006 IBC. The minimum CPSC Category I and II requirements must also be met by replacement glazing. Furthermore, when utilized in any area vulnerable to human impact force, regardless of size, any glazing used in gymnasiums or athletic facilities must meet the more stringent Category II criterion.

Radiant Heat Convection

The transfer of radiant heat through the glazing in fire-rated doors is another safety factor that influences the size of the glazing panel. Fire protective glazing can be utilized up to the maximum size tested for 20 and 45 minute doors. Specialty tempered glass, filmed or laminated ceramics, and filmed wired glass are examples of this.

Temperature rise regulations usually apply when the door rating exceeds 45 minutes. Fire protection glazing for 60 and 90 minute temperature rise doors is restricted to 100 square inches. Designers can, however, go above the 100-square-inch limit by choosing fire-resistant glass that satisfies ASTM E-119, which can limit temperature rise to 250 degrees Fahrenheit. Fire-resistant filled tempered units, tempered multilaminates, and annealed multilaminates are examples. The ASTM E-119 fire resistance specifications are indicated by a “W” on fire resistant glass.

During the fire endurance test, fire resistant glazing is subjected to temperatures of up to 1925 degrees Fahrenheit.

On the non-fire side, the fire resistant intumescent interlayer generates a heat-absorbing char, limiting radiant heat transmission to fewer than 250 degrees above ambient.

Updated codes clarify when fire-resistant vs. fire-resistant glazing should be used.

The International Code Council (ICC) recognized that the IBC’s fire rated glass provisions were confusing in 2009, so it formed an ad hoc committee comprised of fire and building officials, testing agencies, and industry representatives to investigate the provisions and make recommendations for code changes. Three tables in the 2012 IBC were changed as a result of the ad hoc committee’s intensive work over several months. These revisions aren’t new code requirements; rather, they clarify the IBC’s 2006 and 2009 versions.

The ad hoc committee suggested considerable adjustments to the door assembly rating table, 716.5, after analyzing the code’s glazing rules. For the first time, the code provides the view panel size restrictions in table form, as well as a column indicating the sidelite and transom rating requirements. More importantly, the table distinguishes between the use of fire “protection” and fire “resistance” rated products, making it simple for the end user to determine appropriate size limits affecting fire protective glazing; where fire resistance rated products must be used if larger sizes are desired; and where the code would not otherwise allow fire rated glass.

Table 716.5: Opening Fire Protection Assemblies, Ratings, and Markings (Excerpt)

Glazing Panel Size in 60-90 Minute Exit Enclosures/Existing Passageway Doors Clarified by Code Change

Prior to the 2012 IBC, the code allowed fire protective glazing (such as ceramics and wired glass) in door view panels in 60-90 minute exit enclosure and corridor doors to exceed 100 sq. inches if the building was completely sprinklered.

In recognition of the dangers of radiant heat transmission, the ICC ad hoc committee resolved to remove the sprinkler exception from the 2012 IBC. The unrestricted transmission of radiant heat flux through large sizes of fire protective glazing in door vision panels in 60-90 minute doors does not eliminate the life safety and fire spread hazard posed by these doors, especially when these doors are used to protect exit enclosures and exit passageways deemed essential for life safety.

716.5.5.1 In-door glazing Glazing with a fire protection rating of more over 100 square inches (0.065m2) is not authorized. When evaluated as components of the door assemblies, rather than as glass lights, fire resistance rated glazing in excess of 100 square inches (0.065m2) shall be authorized in fire door assemblies, and shall have a maximum end temperature rise of 450 degrees F (250 degrees C) in accordance with 716.5.5.

Even when utilized in a non-temperature rise door in a fully sprinklered structure, fire protective glazing such as safety ceramics and wired glass cannot exceed 100 square inches. It also indicates that fire resistant glass in excess of 100 square inches is permitted as long as the temperature rise after 30 minutes of fire exposure does not exceed 450 degrees F above ambient. As a result, regardless of whether the structure is completely sprinklered or not, the code specifies that fire protective glazing be limited to 100 square inches.

Because the door features fire resistance glazing that meets ASTM E-119, the door vision panels for the 90 minute pair doors are allowed to exceed 100 square inches. If fire-resistant glazing such as safety ceramics or wired glass is used, the door visibility panels will be limited to 100 square inches, which is in contrast to the architect’s goal of maximum vision and transparency in this 2-hour stairwell enclosure.


Fire-rated doors have played an important role in life safety and property protection, and they will continue to do so. Knowing the standards, testing, and code requirements, on the other hand, is critical for appropriately specifying the appropriate and code-approved product for the application. Designers and specifiers can always turn to the manufacturers for advice and assistance.

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