The Code Corner

Openings - Part 2

 

In Part 1, the importance of protecting openings was addressed with a focus on interior windows and doors.  But opening protection is not limited to interior construction; openings in exterior walls are also subject to protection. 

Openings in Exterior Walls

Protection requirements for openings located in exterior walls are determined in a manner completely different than that for interior openings.  One of the most notable differences is that just because an exterior wall is required to be of fire-resistive construction does not mean that openings in that same wall are required to be protected.

Fire-resistive requirements for exterior walls are determined in Chapter 6 of the International Building Code (IBC)¹.  Table 601 sets the fire-resistive construction for exterior bearing and nonbearing walls based on construction type.  For nonbearing walls, Table 601 references Table 602, which determines the fire-resistance rating based on three factors: fire separation distance, type of construction, and occupancy group.  The fire-resistance rating for exterior bearing walls will vary from 1 hour for Type VB construction to 3 hours for Type IA construction, but according to footnote “f” of Table 601, the fire-resistance rating cannot be less than that required by Table 602.  Therefore, if Table 601 indicates that the rating for the exterior bearing wall is 1 hour and Table 602 requires the same wall to be 2 hours, Table 602 governs, and the wall must be of 2-hour fire-resistive construction. 

That explains the requirements for exterior walls, but establishes no criteria for openings.  To determine the fire-resistive requirements for openings, Section 705 must be consulted.  Unlike interior fire-resistance-rated assemblies, where all openings are required to be protected based on the fire-resistance rating of the wall assembly, openings in exterior walls may be unprotected, protected, or a combination of both.  The allowable area of each is determined by the percentages indicated in Table 705.8, based on fire separation distance and sprinkler protection; however, the sprinkler protection only impacts allowable area of unprotected openings.

The percentages provided in Table 705.8 are the maximum areas permitted for openings per story.  For example, if a fire-resistance-rated exterior wall is located 12 feet from the lot line, and the building is two stories in height, then 45% of the wall area of each story is permitted to have protected openings, or unprotected openings if the building is sprinklered throughout; or, if the building is not sprinklered throughout, then 15% of the wall area at each story is permitted to have unprotected openings. 

To better explain how Table 705.8 is applied, consider the building elevation in Figure 1.  Each story is 10 feet in height; the parapet cannot be included in the second story exterior wall area since the IBC definition of “story” is the measurement from the floor to the next floor or roof above, so the measurement must be to the roof line and not to the top of the wall.  Therefore, the area of wall for each story is 750 ft.².  For this example, the building is nonsprinklered and the wall has a fire separation distance of 18 feet. 

To determine if the openings in this building elevation require protection or not, the first step is to determine the actual area of openings per floor.  The first story has a total opening area of 366 ft.² (81 ft.² × 4) + 42 ft.²; the second story has 105 ft.² of openings (21 ft.² × 5).

 
Figure 1 - Building Elevation.

The next step is to determine the percentage of openings per story.  The percentage of openings in the first floor wall area is 49% (366 ft.² ÷ 750 ft.²).  The second story has 14% of its wall area as openings (105 ft.² ÷ 750 ft.²).  With these percentages, we can determine whether or not the openings require protection.

As previously mentioned, the fire separation distance for the wall is 18 feet.  Looking at Table 705.8, each story is permitted to have protected openings in 75% of the wall area or 25% unprotected openings, since the building is nonsprinklered.  The percentage of actual openings at the second floor is 14%, which is less than 25%; therefore, all the windows in this story may be unprotected.  However, the first story has openings which cover 49% of the wall, which exceeds the allowable 25%, but does not exceed the 75% allowable area for protected openings.  Thus, the first floor must have protected opening.

If unprotected openings are desired, then the building must be sprinklered, since 75% of the wall area is permitted to have unprotected openings if the building is sprinklered throughout.  But if sprinklering the building is not an option, and the project cannot afford the cost of protected openings, then there are only two alternatives available:  1) reduce the area of openings so that the percentage is equal to or less than the allowable area for unprotected openings, or 2) provide a mix of protected and unprotected openings to reduce the area of protected openings required.  The first one is easy, but may not achieve the desired result.  The second one requires some manipulation to achieve compliance.

Therefore, in the example, the door will be considered unprotected and the storefront glazing is protected.  If a combination of protected and unprotected openings are used, then the sum of the ratios of actual to allowable areas cannot exceed 1, which is provided by Equation 7-2 in the IBC:  (A_p/a_p)+(A_u/a_u) ≤ 1, where A_p is actual area of protected openings, a_p is allowable area of protected openings, A_u is actual area of unprotected openings, and a_u is allowable are of unprotected openings.  The allowable area for protected openings (a_p) would be 75% of the wall area for the story, or 562.5 ft.², and the allowable area for unprotected openings (a_u) would be 25% or, 187.5 ft.².  Since the actual area of the door is 42 ft.² (A_u) and the actual area of the storefront glazing is 324 ft.² (A_p), the equation would be set up as follows:

(A_p/a_p) + (A_u/a_u) = (324 ft.²/562.5 ft.²) + (42 ft.²/187.5 ft.²) = 0.576 + 0.224 = 0.8 ≤ 1

The discussion thus far has only mentioned openings as either protected or unprotected, with no mention of the requirements for a protected opening in the discussion of fire-resistance ratings.  For openings in exterior walls, the fire-resistance ratings are provided in Table 715.4.  For walls with a 1-hour fire-resistance rating, openings are required to have a ¾-hour or greater rating.  For exterior walls with a 2- or 3-hour fire-resistance rating, the openings must have a 1½-hour or greater rating.  If our example building is of Type VA construction with a Group B occupancy, and the wall is nonbearing, then the fire-resistance rating of the wall would be 1-hour per Tables 601 and 602.  Therefore, the openings in the wall would need to have a ¾-hour rating.

Walls Not Parallel With Lot Lines

Determining protected openings is easy when the exterior walls are parallel with the lot line; however, not all buildings are constructed square with their lots nor are all lot shapes rectilinear.  So when a building has an exterior wall that is not parallel with the adjacent lot line, the determination of protected openings gets a little more complicated.  The easy approach is to use the fire separation distance between the exterior wall and the lot line at the closest point and apply that percentage to the entire length of the exterior wall.  However, that can be a somewhat overly restrictive.

Even though the IBC does not address nonparallel exterior walls and lot lines, the following method uses the IBC principles of exterior wall opening protection in a segmental application over the entire length of the wall (See Figure 2). 

 Figure 2 - Opening protection for angled lot lines. (P) Protected; (UP,S) Unprotected, Sprinklered; (UP, NS) Unprotected, Nonsprinklered.

The method requires establishing lines parallel to the wall in question at distances equal to the ranges used in Table 705.8.  The reason the lines are parallel to the wall is that fire separation distance is measured perpendicular to the wall and not the lot line per IBC definition.  At the point where each distance line intersects the lot line, establish another line perpendicular to the distance line back to the building’s wall.  These lines create the zones of fire separation distance along the length of the exterior wall.

For each zone, determine the length and identify the permitted allowable opening percentage.  The percentage is then applicable to each zone based on the area for that zone (length of zone × story height).  Using the example in Figure 2, if the building had a story height of 13 feet and it was nonsprinklered, the permitted unprotected opening areas would be as follows:

• Zone A:  No openings permitted
• Zone B:  15.6 ft.² (12 ft. × 13 ft. × 10%)
• Zone C:  23.4 ft.² (12 ft. × 13 ft. × 15%)
• Zone D:  39 ft. ² (12 ft. × 13 ft. × 25%)
• Zone E:  40.95 ft.² (7 ft. × 13 ft. × 45%)

The same process is used for each zone for protected openings, or for unprotected openings if a sprinkler system is installed throughout.  For a combination of protected and unprotected openings, the same process described earlier for mixed openings is used, but is applied to each zone separately.

Exterior Opening Exceptions

There are several exceptions to the requirements for openings in exterior walls.  In Section 705.8.1 there are two exceptions.  The first exception applies to openings in the first story for all occupancy groups except Group H and has two conditions, of which only one or the other needs to be met.  The first condition allows unlimited unprotected openings when the exterior wall faces a street and has a fire separation distance greater than 15 feet.  The second condition allows unlimited unprotected openings when the exterior wall faces an occupied space that is at least 30 ft. wide and is accessed by a street using a fire lane.  This condition may seem odd, since Table 705.8 allows unlimited unprotected openings when the fire separation distance is 30 ft. or greater.  However, this condition permits the open space to be one that is not on the building’s lot, as long as the space is dedicated for public use or is an open space between buildings on the same lot².

The second exception to Section 705.8.1 allows unlimited unprotected openings when the exterior bearing and nonbearing walls, as well as the exterior primary structural frame, are not required to be fire-resistance rated.  Therefore, this exception would only apply to Types VB, IIIB, and IIB; and if a sprinkler system is used to substitute for 1-hour construction, the exception would also apply to Types VA, IIIA, and IIA.

Although not technically considered exceptions, the footnotes of Table 705.8 also provide some alternatives to the general requirements for exterior wall opening protection.  Footnote “d” allows 25% of the wall area to have protected and unprotected openings in a Group R-3 building when the fire separation distance is 3 feet to less than 5 feet; footnote “e” does not permit openings for Groups H-2 and H-3 when the fire separation distance is less than 15 feet; footnote “f” allows unlimited protected and unprotected openings for Group R-3 when the fire separation distance is 5 feet or greater; and the area of openings in an open parking structure is not limited when the fire separation distance is 10 feet or greater.

Vertical Separation of Openings

Openings in exterior walls may need to be vertically separated in accordance with Section 705.8.5. If openings in adjacent stories are within 5 feet of each other (See Figure 3) and the window in the story below is unprotected, then the openings must be separated by a 3-foot, 1-hour fire-resistant-rated spandrel or a 30-inch, 1-hour fire-resistant-rated horizontal flame barrier (See Figure 4).  As always, there are exceptions to the requirements.

 
Figure 3 - Horizontal distance that requires compliance with vertical separation requirements.

 
Figure 4 - Vertical separation of openings in exterior walls.  (A) Provides separation by use of vertical, fire-resistance-rated spandrel.  (B) Provides separation by use of horizontal, fire-resistance-rated flame barrier

The exceptions exclude buildings under certain conditions from complying with the vertical separation requirements.  The first exception is for buildings that have three or fewer stories above grade plane.  The second applies to any building that is sprinklered throughout with either an NFPA 13 or NFPA 13R system.  The final exception applies to all open parking garages.

Alternate Methods for Determining Fire Ratings of Openings

As mentioned in Part 1 of this article, one of the standards for fire-resistance-rated doors is NFPA 252.  For fire-resistance-rated windows, the acceptable standards include NFPA 257 and UL 9.  For alternative methods of determining fire-resistance ratings of openings, the IBC identifies four methods or procedures in Section 715.3.  However, whichever method or procedure is selected, it must be based on one of those three standards.

The four methods and procedures listed in the IBC include 1) designs documented in approved sources, 2) calculations performed in an approved manner, 3) engineering analysis based on comparison to openings with a fire rating determined by one of the three standards, and 4) alternative methods allowed by Section 104.11.  The first method allows selecting openings that have been tested and listed in various sources such as UL and FM Global.  The second requires using a calculated method that has been approved by the building official; this may require consulting a specialist, which is also likely for the third method.  The fourth method allows the use of the alternative materials, design and methods section of the IBC, which may require a research report, testing, or both.

Windows that are not Openings

Even though this two-part article series is titled “Openings,” it would not be complete without a discussion on windows that are not considered openings, but are in fact considered fire-resistance-rated walls.  Section 715.2 states that glazing tested in accordance with ASTM E 119, Test Methods for Fire Tests of Building Construction and Materials, or UL 263, Standard for Fire Test of Building Construction and Materials, are not subject to the requirements of Section 715 for opening protectives. 

A few manufacturers provide products that have been tested using these two standards and are thus not openings, but more like “fire-rated transparent walls,” since they have been tested using the same standards as required for fire-resistance-rated wall assemblies, such as fire walls and fire barriers.  Although not currently addressed in the IBC, glazing that has been tested and has passed the requirements of ASTM E 119 or UL 263, including the prevention of radiant heat, are given the “W” mark for “Walls” in lieu of the “D” and “OH” marks mentioned in Part 1 of this article³.  Therefore, they can be included in exterior and interior locations where fire-resistance-rated assemblies are required and not be limited to the size and area restrictions for openings.  Fire-rated transparent walls may have unlimited area as long as each lite of glazing, bounded by the frame, does not exceed the maximum tested area.

Another difference between glazed openings and fire-rated transparent walls is the required fire-resistance rating.  As mentioned earlier in this article series, the fire-resistance ratings for openings are, in most cases, lower than the fire-resistance rating of the walls in which the openings are installed.  However, fire-rated transparent walls, when installed in place of typical fire-resistance-rated wall assemblies, must have a fire-rating that is equal to or greater than the required rating for the wall assembly.  For example, if the required rating for a fire barrier used as an occupancy separation is 2-hours, then the rating for the fire-rated transparent wall must also be 2 hours or greater.

While many fire-rated glazing systems are manufactured using ceramic, wired, or specialty tempered glass, fire-rated transparent walls utilize tempered glazing that is laminated with an intumescent interlayer.  When a fire reaches a temperature to shatter the tempered glass on the fire side, the intumescent layer will create a char that will insulate the opposite side from radiant heat transfer.

There are a couple of things to keep in mind when considering the use of fire-rated transparent walls.  The first thing to consider is the cost; fire-rated transparent walls are not inexpensive.  The second is possible resistance from the local building department to accept these systems as anything but openings.  This resistance is usually derived from the misconception that “if you can see through it, then it’s an opening.”  Even though this perception is contrary to the IBC, building departments are made up of people, and it may take some effort on the part of the design team to convince the local building department that these systems are in compliance with the code.

Coordination with Other Requirements

The placement of openings in fire-resistive assemblies must be carefully considered to ensure that maximum allowable areas are not exceeded; but coordination with other sections of the IBC is just as important.  Fire-resistance-rated doors must also conform to the means of egress requirements of Chapter 10, and fire-resistance-rated windows need to comply with the safety glazing requirements of Chapter 24 when located in one or more of the hazardous locations listed.  Additionally, exterior fire-resistance-rated openings are subject to the structural load requirements of Chapters 16 and 24, as well as the energy requirements of the International Energy Conservation Code, if adopted.

Protected openings are essential in order to make buildings functional when fire-resistive construction is required by the building code.  Otherwise, to move from one fire area⁴ to the next would require exiting and reentering the building.  Just installing a door or window in these assemblies is not enough; the fire-resistive performance of the wall assembly must not be significantly compromised.  Therefore, opening protection is required to maintain that minimum fire-resistive performance.

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¹   References to the IBC in this article are for the 2009 Edition.

²   Typically, fire separation distance between buildings on the same lot is measured between the face of the wall and an imaginary line between the buildings.

³   The “W” mark has been approved for the 2012 Edition of the IBC.

⁴   A “fire area” is defined in the IBC, in part, as “The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or horizontal assemblies of a building.”

Openings - Part 1

 

“The act or an instance of becoming open or being made to open.”  “An open space serving as a passage or gap.”  “An unfilled job or position; a vacancy.”  “A breach or aperture.”¹

The word “opening” has many meanings, as indicated above.  However, with its many specific code-related definitions, it is surprising that the International Building Code (IBC)² does not provide its own definition of “opening.”  So, in the absence of a code-specific definition, the latter definition from the above list is very apt when referring to doors, windows, and other “breaches” in fire-resistance-rated assemblies. 

Fire-resistance-rated assemblies (i.e. fire walls, fire barriers, fire partitions, smoke barriers, and horizontal assemblies) have been tested to restrict the spread of fire; but openings, such as doors and windows, located in these assemblies, introduce points of weakness.  Therefore, openings in a fire-resistance-rated assembly must afford some protection to maintain a minimum level of fire resistance throughout the extent of the assembly.  The IBC establishes requirements for openings in Chapter 7 in three locations.  The first location is Section 705.8 for openings in exterior walls; the second location is Section 712.8 for floor doors in horizontal assemblies; and finally, the third location is Section 715, which is titled “Opening Protectives”—the primary location for opening requirements.

Standards for Openings

In order for an opening to be used in a fire-resistance-rated assembly, the opening must be tested in accordance with the standards indicated in the IBC based on type of opening.  The IBC defines three types of openings:  the fire door assembly, the fire window assembly, and the floor fire door assembly, which is used only in the horizontal position.  The use of the word “assembly” with each of these terms indicates that it includes all components necessary for a complete opening, such as frames, hardware, glazing, and other accessories.

For side-hinged and pivoted swinging doors, the applicable test standards are National Fire Protection Agency’s (NFPA) 252, Standard Methods of Fire Tests of Door Assemblies, or Underwriters Laboratories (UL) 10C, Positive Pressure Fire Tests of Door Assemblies.  Other doors are required to be tested in accordance with either NFPA 252 or UL 10B, Fire Tests of Door Assemblies. 

The positive pressure requirement for fire door assemblies was introduced in the 1997 Uniform Building Code after much debate and has remained a requirement in the IBC.  It was expected that the hose stream requirement for fire doors would be eliminated from test standards if positive pressure was incorporated, but the hose stream test (discussed in the next paragraph) has remained in U.S. fire door test standards.  UL 10C integrates the positive pressure requirements into the test standard; however, NFPA 252 does not, so the IBC requires that the neutral pressure plane be moved to 40 in. or less above the sill after 5 minutes into the test.  The positive pressure requirement provides a more realistic condition experienced by fire door assemblies during an actual fire event (See Figure 1).

The hose stream portions of the UL 10C and NFPA 252 tests are not indicative of an assembly’s ability to withstand firefighting operations, but to test the structural durability of the assembly through thermal shock from the cool water and the impact and scouring effect of the water blast against the assembly.  Fire door assemblies in walls of corridors and smoke barriers are not required to pass the hose stream test of either standard.

  

Figure 1 - Positive Pressure Requirement

An exception to the tests above are those doors that have been tested in accordance with UL 10A, UL 14B, and UL 14C.  The doors applicable to these standards are tin-clad fire doors usually constructed of a wood core with sheet metal applied to faces and edges.  Historically, tin-clad doors were often associated with old warehouses, and may be of the swinging, horizontally sliding, or vertically sliding types.  Even so, some manufacturers continue today to fabricate doors of this type. 

Another exception to the door testing requirements is for floor fire door assemblies.  Doors of this type are required to be tested in accordance with NFPA 288, Standard Methods of Fire Tests of Floor Fire Door Assemblies Installed Horizontally in Fire Resistance-Rated Floor Systems.  Where openings are needed in a fire-resistance-rated horizontal assembly, the floor fire door can be a solution.  Floor doors are subject to fire exposure that is different from that experienced by standard vertical fire doors, such as the lack of differential pressure along the plane of the door surface and exposure to higher temperatures from the rising heat.

For fire window assemblies, the required tests are either NFPA 257, Standard on Fire Tests for Window and Glass Block Assemblies, or UL 9, Fire Tests of Window Assemblies.  The only exceptions to these standards are wired glass and glazing complying with the requirements of ASTM E 119, Standard Test Methods for Fire Tests of Building Construction and Materials, or UL 263, Fire Tests of Building Construction and Materials.  The latter exception will be addressed in detail in Part 2 of this article.  Like fire door assemblies, fire window assemblies are also required to be tested under positive pressure, but only within 10 minutes of test start and at a height that leaves two-thirds of the window above the neutral plane.

Fire Door Assemblies

The required fire protection rating of a fire door assembly is based upon both the rating and the type of fire-resistive assembly in which the fire door assembly is located.  Like fire-resistive assemblies, the fire protection ratings for fire door assemblies are also given in hours.  Fire protection ratings are provided in Table 715.4 of the IBC. 

Fire door assemblies, at a minimum, must be provided with a label complying with the requirements of NFPA 80, Standard for Fire Doors and Other Opening Protectives, and shall bear the name of the manufacturer or the manufacturer’s traceable identification number, the name or trademark of the third party inspection agency, and the fire protection rating (See Figure 2).  Frames for fire door assemblies are also required to have a label, but it is not required that the fire protection rating be included.

In addition to controlling the spread of fire, fire door assemblies must also control drafts and the passage of smoke.  To measure a fire door assembly’s performance in these areas, the assembly shall be tested in accordance with UL 1784, Air Leakage Tests of Door Assemblies.  New in the 2009 edition of the IBC is the basic acceptable performance level with which fire door assemblies must comply.  Doors complying with the smoke and draft control requirements shall be identified with an “S” on the required label.

 
Figure 2 - Fire Door Label Example

If a door that requires a fire protection rating is larger than the fire door assembly that was tested, then the required label mentioned earlier will need to indicate the door is oversized. Another option is to have an approved testing agency provide a certificate of inspection attesting to the fact that the door is constructed in the same manner as the tested fire door assembly.

Fire door assemblies located in exit enclosures and exit passageways are required to minimize the transmission of heat from the exposed side through the door to the unexposed side, thus reducing the amount of radiant heat occupants may experience while egressing through the exits.  The IBC requires that the temperature rise on the unexposed surface of the fire door assembly cannot exceed 450°F above the ambient temperature at the end of a 30 minute period.  Fire door assemblies that are required to comply with this requirement must have that shown on the required labels (See Figure 2).  Further, if glazing in the fire door assembly exceeds 100 in.², then the glazing must also pass the temperature rise criteria.  Buildings that are equipped throughout with an automatic sprinkler system in accordance with either NFPA 13 or NFPA 13R are not required to comply with either temperature rise provision.

For obvious reasons, the IBC precludes the use of louvers in fire doors.  However, UL provides listings for fire door louvers used in fire doors with fire protection ratings up to 1½-hour.  The UL requires that such louvers be tested in accordance with UL 10B or UL 10C—the same tests to which fire door assemblies are subjected.  With regard to the specific prohibition in the IBC, designers should obtain approval from the building official before incorporating a UL-listed louver into a fire door assembly.

In fire walls, the area of fire door assembly openings is limited to 156 ft.² unless the buildings on each side of the fire wall are sprinklered throughout in accordance with NFPA 13—NFPA 13R systems are not allowed that exception.  Additionally, the aggregate width of openings on any floor level cannot exceed 25% of the overall length of the fire wall.

Glazing in fire door assemblies is permitted, but some restrictions do apply.  According to NFPA 80, glazing is permitted when tested as part of the fire door assembly.  The IBC indicates that glazing shall have a fire protection rating equal to the rating required for the fire door assembly.  The size of glazing in a fire door assembly is limited by NFPA 80 and the IBC.  NFPA 80 limits the area of glazing to that tested as part of the fire door assembly.  However, ¾-hour doors are limited to a maximum area of 1296 in.² with a maximum dimension not exceeding 54 in.  Additionally, in 3-hour doors, NFPA 80 limits the glazed area to a maximum of 100 in.².  The IBC further restricts glazing to 100 in.² in 1½-hour fire door assemblies that are installed in fire barriers.

Glazing used in fire door assemblies shall be permanently labeled with a four-part identification code.  The first part of the identification code is the letter “D,” which indicates that the glazing is suitable for a fire door application and has been tested in accordance with NFPA 252.  The second part is either an “H” or “NH,” which indicates that the glazing has passed or not passed, respectively, the hose stream requirements of NFPA 252.  The third part is either a “T” or “NT,” which indicates the glazing complies or does not comply, respectively, with the temperature rise requirements of the IBC.  And finally, the fourth part is the fire protection rating in minutes.  Thus, an identification code such as “D—H—NT—120” translates into glazing suitable for a 2-hour fire door that has passed the hose stream test, but has not passed, or was not tested for, the temperature rise requirement.

Glazing utilized in fire door assemblies must also comply with the safety glazing requirements of the IBC.  Chapter 24 of the IBC requires that glazing in doors comply with the requirements for Category I glazing as established by test in accordance with the Consumer Product Safety Commission (CPSC) 16 CFR 1201, Safety Standard for Architectural Glazing Material.  Category I safety glazing will withstand a 100 pound weight swung from a pendulum at a distance of 18 in. from the glass surface.  If the area of glazing exceeds 9 ft.², then the glazing must comply with Category II requirements, which increases the distance of the weight in the test to 48 in. from the glass surface.

A discussion on fire door assemblies would not be complete without addressing door hardware.  A fire door assembly is required to have a latch that will secure the door when closed, preventing passage of smoke and fire into the unexposed side.  But a latch would be useless if the fire door assembly is allowed to remain open, therefore IBC Section 715.4.8 requires that fire door assemblies be provided with closers that are either automatic- or self-closing, unless they are installed in walls separating sleeping units in Group R-1 occupancies.

Generally, “self-closing” requires the use of standard door closers that will close and latch the door when released.  “Automatic-closing” usually includes devices such as magnetic door holders that release doors when triggered by an alarm situation.  However, Section 715.4.8.2 states that automatic-closing fire door assemblies “shall be self-closing in accordance with NFPA 80.”  Therefore, the language of the IBC seems to limit all fire door assemblies to the “self-closing” type, even though NFPA 80 permits the use of “automatic-closing” fire door assemblies. 

But Section 715.4.8.3 identifies where smoke-activated, automatic-closing fire door assemblies may be installed.  These locations include doors across corridors; doors in smoke barriers, fire walls, fire partitions, and shaft enclosures; as well as in other locations.  The actuation of the closer is limited to a 10-second delay after being triggered by a smoke detector or loss of power to the smoke detector or hold-open device.  Overhead sliding or rolling fire door assemblies are permitted to be actuated by either heat- sensitive devices, such as a heat detector or fusible link, or smoke detectors connected to the building alarm system.

Transoms and sidelights that are a part of the frame for a fire door assembly are permitted provided the fire protection rating of the assembly is ¾-hour or less.  For fire door assemblies exceeding a ¾-hour rating, transoms and sidelights must comply with either ASTM E 119 or UL 263.  Glazed units that are not part of a fire door assembly shall comply with requirements for fire window assemblies.

Fire Window Assemblies

The required fire protection ratings of fire window assemblies are provided in IBC Table 715.5 and are based on the type and rating of fire-resistive assembly in which the windows are installed.  For interior construction, fire windows are limited to fire-resistive assemblies that have ratings of 1 hour or less.  Therefore, all fire walls and fire barriers with ratings of 2 hours or more are not permitted to have fire window assemblies.  In all cases where fire window assemblies are permitted, the area of a fire window assembly cannot exceed 25% of the common wall area in any room (See Figure 3).

Figure 3 -  Common Wall Area Determination

The size of a single pane of glazing in a fire window assembly is limited to 1296 in.² with no dimension exceeding 54 in. unless tested to a larger size, dimension, or both.

Wired glass assemblies are one of the exceptions to the testing requirements for fire window assemblies.  Wired glass that is ¼-inch thick set in steel frames having a metal thickness not less than 0.125 in. are considered to meet the requirements for a ¾-hour fire window assembly.  The maximum area of wired glass permitted under this exception is an absolute 1296 in.² with no dimension exceeding 54 in.  Wired glass assemblies that have been tested in accordance with the standards for fire window assemblies are permitted to have larger glazed areas and dimensions if tested at those larger sizes.

Like glazing in fire door assemblies, glazing in fire window assemblies are also required to be of safety glazing if located in areas identified in Chapter 24.  The only exception is that glazing in fire window assemblies may be tested in accordance with the recently updated ANSI Z97.1, Safety Glazing Materials Used in Buildings—Safety Performance Specifications and Methods of Test, in lieu of the CPSC 16 CFR 1201 standard.

Fire-protection-rated glazing used in fire window assemblies must also be permanently marked with a label or other identification that provides the name of the manufacturer, the test standard, and a two-part identification code. The first part of the identification code is “OH,” which indicates that the glazing is suitable for an opening and has passed the hose stream test.  The second part of the identification code is the fire protection rating in minutes.  Therefore, fire-protection-rated glazing with the identification code “OH—45” indicates the ¾-hour glazing is suitable for openings and has passed the hose stream test.

Installation

Fire door and fire window assemblies are required to be installed in accordance with NFPA 80.  Doors required for smoke and draft control must be installed in accordance with NFPA 105, Standard for the installation of Smoke Door Assemblies.  NFPA 80 limits the clearance at the bottom of a fire door to a maximum of ¾ in.  above the floor and the clearance between the top and vertical edges of the door and door frame is ⅛ in. (± 1/16 in.)  for steel doors and a maximum 1/8 in. for wood doors.

Openings—Part 2

Part 2 of this article will address openings in exterior walls, including calculating allowable area of protected and unprotected openings based on fire separation distance.  Also included will be information on alternate methods used to determine fire protection ratings of openings.  Part 2 will wrap up with a brief discussion on when a window is not considered an opening.

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¹ The American Heritage Dictionary of the English Language, Fourth Edition, 2000, Houghton Mifflin Company.

² References to the IBC in this article are for the 2009 Edition.

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