The Code Corner

High-Hazard Occupancies

The TRW plant located in Mesa, Arizona, has experienced a number of problems: explosions, fires, and medical emergencies. Hundreds of them in a time span of less than ten years. An explosion in 1995 cost the life of one worker. The situation became such a concern that the Mesa Fire Department issued a cease and desist order to the owner that lasted a couple of days, but only until TRW agreed to improve conditions. So what was at the center of all these events? The answer: sodium azide—a chemical used in the manufacture of automobile airbag devices. Although sodium azide (NaN₃) is not classified as an explosive (it is a toxic poison), when heated, the chemical reaction generates an explosive event.

It should be obvious to anyone reading the previous paragraph that those facilities associated with the TRW plant are hazardous occupancies. More specifically, the International Building Code (IBC) considers occupancies such as this as high-hazard or Group H occupancies. The IBC describes a high-hazard occupancy as one "that involves the manufacturing, processing, generation or storage of materials that constitute a physical or health hazard in quantities in excess of those allowed[.]" The key to classifying a building as a Group H occupancy lies within the last few words of that quote: in excess of those allowed. Without that provision, every building that has certain cleaning products in a janitorial closet would be considered a Group H occupancy.

So if hazardous materials are permitted in other occupancy groups, what is the threshold that divides any other occupancy group from a Group H occupancy? To determine the answer to that question, there are three things the design professional needs to know: 1) the categories of hazardous materials that will be used; 2) how each category of hazardous material will be used, such as storage only, in an open system, or in a closed system; and 3) quantity of each category of hazardous materials for each use indicated. These are discussed in detail later in the article.

In Section 307.1, the IBC identifies thirteen exceptions that exclude certain occupancies and uses from the Group H classification. If none of the exceptions apply, then the hazardous occupancy will be categorized into one of five subgroups. As delineated in the descriptions below, the most severe hazardous occupancy group is H-1 and the hazard severity gradually decreases as the occupancy group number increases.

• Group H-1 includes occupancies containing materials with a detonation potential.
• Group H-2 includes occupancies containing materials that have a deflagration potential or that create a hazard from accelerated burning.
• Group H-3 includes occupancies containing materials that are easily combustible or pose a "physical hazard."
• Group H-4 includes occupancies containing materials that pose a "health hazard." The IBC defines a health hazard to include toxic, highly toxic, and corrosive chemicals.
• Group H-5 includes occupancies containing hazardous production materials (HPM) used in semiconductor fabrication and research and development laboratories.

Categories of Hazardous Materials

The topic of hazardous materials is a rather large one and would take volumes of text to explain all of the issues involved. However, in the context of the IBC, hazardous materials are sorted into two major categories, physical hazards and health hazards; both are defined by the International Fire Code (IFC)¹. The table below lists the categories of materials for each of the major hazard categories.

Physical Hazards		Health Hazards
Combustible dust Combustible liquid Combustible fiber Consumer fireworks Cryogenics, flammable Cryogenics, inert Cryogenics, oxidizing Explosives Flammable gas	Flammable liquid Flammable liquid, combination Flammable solid Organic peroxide Oxidizer Oxidizing gas Pyrophoric material Unstable (reactive) Water reactive	Corrosive Highly toxic Toxic

Table 1 – Hazardous material Categories.

Determining a chemical's hazard category should not be difficult. The best method is to obtain a copy of the material safety data sheet (MSDS). The Occupational Safety and Health Administration (OSHA) establishes a recommended 16-section format for MSDSs. The section that will likely provide the hazard category for a material is Section 14, "Transport Information." If the hazard category description per the IBC is not used in the MSDS, it is likely that the U.S. Department of Transportation (USDOT) hazard class will be provided (See Figure 1). The Code of Federal Regulations (CFR) provides additional information on the hazard classes (49 CFR, PART 172, Subpart B).

Figure 1 - A portion of a MSDS for sodium azide. Per USDOT regulations, the hazard class of 6.1 indicates that this chemical is "toxic"; thus, it is considered a health hazard placing it in Group H-4 if the quantity exceeds that allowed.

Another source that may be helpful is "Appendix E: Hazard Categories" located in the IFC. Unlike other appendices used in the International Codes, this appendix is informational only and does not require adoption to be used. The terminology used in this appendix follows closely to that used in the code text; however, the examples provided for each are limited and may not include chemicals that are not commonly used.

Use and Quantity of Hazardous Materials

After identifying the categories of hazardous materials, one needs to determine the quantities that will be used—not just stored quantities, but also the quantities that are in use. The IFC and IBC identify two types of use systems: open and closed.

A closed system, as defined by the IFC, includes a vessel and associated piping that does not permit the release of vapors from a solid or liquid chemical or does not expose the chemical to the atmosphere at any time during its use. An open system is defined as a vessel or system that is continuously open that allows vapors from a solid or liquid chemical to be released or exposes the chemical to the atmosphere during its use.

Storage, as used within the IFC/IBC context for hazardous materials, includes materials that are both in use (open or closed systems) and in storage for future use or for disposal.

Determining Group H Classifications

Once the two essential pieces of information are gathered (i.e. quantity and use of hazardous materials), then the task of determining if a Group H occupancy is applicable can begin. IBC Tables 307.1(1) and 307.1(2)² provide the maximum allowable quantities of hazardous materials within a control area for physical hazards and health hazards, respectively.

A control area is defined in the IFC as "[s]paces within a building where quantities of hazardous materials not exceeding the maximum allowable quantities per control area are stored, dispensed, used or handled." IBC Section 414.2 (IFC Section 5003.8.3) establishes the construction criteria for control areas, which consist of fire barriers per IBC Section 707 and horizontal assemblies per IBC Section 711. The fire-resistance rating for the fire barriers and horizontal assemblies are dependent upon the height of the control area in stories above the grade plane³ per IBC Table 414.2.2 (IFC Section 5003.8.3.2). Any control area on the fourth story or higher requires a 2-hour rating and anything below, including up to two stories below the grade plane, requires a 1-hour rating. Control areas are not permitted any lower than two stories below the grade plane. If a building has no identified control areas or no fire-resistive construction required by other provisions of the IBC complying with the requirements for control areas, then the entire building would be considered a single control area. See "Control Area Limitations" later in this article for additional requirements.

Returning to the tables, when the category of a chemical is confirmed, locate the category in column  of either Table 307.1(1) (See Figure 2) or Table 307.1(2) (See Figure 3). The next step is to determine the quantity allowed based on how the material is used and stored. Column ƒ provides maximum quantities for storage, column „ for closed systems, and column … for open systems. If the actual quantities used or stored exceed the quantities listed in the table, then the building must be classified per the occupancy group indicated in column ‚. Table 307.1(2) does not have this column, so quantities exceeding those in this table are classified as Group H-4. The only alternative to classifying the building as a Group H is to provide additional control areas, each having quantities not more than those indicated in the tables.

Figure 2 - A portion of IBC Table 307.1(1) for maximum quantities of a hazardous material in a control area. Since the material indicated in this portion of the table is only a solid, there are no quantities indicated for liquids or gases.

Figure 3 - A portion of IBC Table 307.1(2) for maximum quantities of a hazardous material in a control area. Since these are for chemicals posing a health hazard, if maximum quantities are exceeded, then the building or portion thereof must be classified as a Group H-4.

Using magnesium as an example, that material is considered a flammable solid. Therefore, Table 307.1(1) is applicable (See Figure 2). If the magnesium is only stored, then up to 125 cu. ft. of the material may be stored within the control area. If the actual stored quantity is expected to be 250 cubic feet, then the building is either classified as a Group H-3 or two control areas are provided, each with an allowable quantity of 125 cu. ft. If the magnesium is used in an open system, then the most that can be exposed is 25 cu. ft. However, that does not mean that 125 cu. ft. of stored material and 25 cu. ft. of exposed material—a total of 150 cu. ft.—is permitted in the control area. The quantities of material in use and in storage cannot exceed the storage quantity, or 125 cu. ft. in the case of this example.

There are numerous footnotes to each of these tables—more than what can be covered in this article; however, there are a couple of notable ones that should be discussed. One footnote allows some quantities in the tables to be increased 100% if a sprinkler system is installed per National Fire Protection Association's standard NFPA 13, Installation of Sprinkler Systems.⁴ Another footnote allows some quantities in the tables to be increased 100% if storage is in an approved storage cabinet, enclosure, or safety can that complies with IFC Section 5003.9.10.⁵ Both of these footnotes are accumulative, which means that if both footnotes are applicable, then the allowable quantity in the table may be increased four times.

Control Area Limitations

IBC Table 414.2.2 was previously mentioned regarding the fire resistance of assemblies enclosing control areas based on height in number of stories. In addition to fire resistance, the table also limits the quantities within a control area and the number of control areas per story based on height. For control areas located on the first story above grade plane, 100% of the allowable quantities—as determined using the process provided in the previous paragraphs—is permitted, and the maximum number of control areas is four. However, when control areas are located higher than the first story and below the grade plane, then the quantities of allowable materials are reduced, as well as the number of allowable control areas. For example, if a hazardous material is located on the third story, only 50% of the maximum allowable quantities per Tables 307.1(1) and 307.1(2) are allowed and the number of control areas is limited to two.

Relief for Group M and Group S Occupancies

Group M display and storage areas and Group S storage areas are given some relief in IBC Section 414.2.5 (IFC Section 5003.8.3.5). These occupancy groups are permitted quantities that exceed Tables 307.1(1) and 307.1(2) without classifying the building or use as a Group H occupancy. There are three caveats to this provision: 1) materials are displayed and stored in accordance with the IFC; 2) the quantities do not exceed those indicated in IBC Table 414.2.5(1) (IFC Table 5003.11.1) per control area; and 3) the materials are nonflammable solids, nonflammable liquids, or noncombustible liquids⁶.

Similar to the other tables that establish maximum quantities, Table 414.2.5(1) also has an extensive list of footnotes—two of which are nearly identical to the footnotes in the other tables for increases due to sprinkler system installation (footnote 'b') and storage in approved cabinets (footnote 'c'). These, too, are accumulative; therefore, a total of four times the indicated quantities are permitted if both footnotes are applicable.

Special Provisions for Group H

IBC Section 415 includes special provisions for Group H occupancies; some are general in scope and others are applicable to a specific Group H occupancy. The general requirements include an automatic fire detection system (IBC Section 415.3) and a sprinkler system installed throughout (IBC Section 415.4).

Group H occupancies also have specific fire separation distances that must be met even if other provisions of the IBC allow a closer distance. Furthermore, the distances are measured from the walls enclosing the occupancy, whether they are interior or exterior walls, to the nearest lot line—even if that lot line is on a public way (i.e. cannot measure to the center of the public way as provided in the definition for fire separation distance) (See Figure 4). The required fire separation distances per occupancy consist of the following:

• Group H-1:  75 feet, but not less than that required by the IFC Chapter 56. Buildings used for fireworks manufacturing are required to comply with the distances in NFPA 1124, Code for the Manufacture, Transportation, Storage, and Retail Sales of Fireworks and Pyrotechnic Articles.
• Group H-2:  30 feet when the area of the Group H-2 occupancy exceeds 1000 sq. ft. and is not required to be a detached building.
• Group H-2 and H-3:  50 feet when a detached building is required.
• Group H-2 and H-3 (containing materials with explosive characteristics): Per IFC Section 5601.8.

Figure 4 - Measurement of fire separation distances for Group H occupancies. Distances are measured to lot lines (Distance ‘B’) and assumed lot lines (Distance ‘C’; except for manufacturing and use of explosives when quantity distances are used). Measurement is also to lot lines adjacent to public ways (Distance ‘A’) and not to centerline.

For buildings where explosives are manufactured or used and required separation is determined using the quantity distances in accordance with the IFC, the fire separation distance shall be the dimension measured between buildings and not to assumed lot lines, since quantity distances are much farther than normal fire separation distances.

Detached buildings for Groups H-1, H-2, and H-3 are required when the quantities exceed those indicated in IBC Table 415.5.2 (IFC Table 5003.8.2). If a detached building is required, wall and opening protection based on fire separation distance is not required. Specific requirements for each of the Group H occupancies are provided in IBC Sections 415.6 through 415.10 and are too numerous to discuss in this article.

Special Requirements for Hazardous Materials

Regardless of whether hazardous materials are located in Group H occupancies or other occupancy groups, the buildings and adjacent areas where they are located must comply with some minimum requirements. The IBC and IFC provide requirements for the storage, dispensing, and use of hazardous materials for interior and exterior conditions. The IFC has extensive requirements contained in 18 chapters located in Part V. The IBC, however, provides two sections, 414.5 and 414.6, that address the building requirements related to these conditions, most of which reference back to the IFC.

For indoor conditions, explosion control is required for some chemicals that have explosive characteristics, whether they are classified as explosives or not. IBC Table 414.5.1 lists the material categories that pose an explosive hazard. For each category, the table indicates whether a barricade or explosion venting/prevention system is required. If a chemical's explosive characteristic is based on deflagration⁷, the requirement is to provide venting or another method that prevents the potential for an explosion. If mechanical ventilation is provided, emergency or standby power is required unless one of the exceptions is applicable. Explosions created by detonation⁸ are managed through barricade construction that deflects, vents, or withstands the blast overpressure.

Spill control and secondary containment is required for indoor and outdoor storage of hazardous materials. The intent of spill control is to prevent the flow of hazardous liquids into adjacent areas. Spill control is required for liquids in individual containers of more than 55 gallons or when the aggregate stored capacity in multiple containers exceeds 1000 gallons. IFC Section 5004.2.1 provides four methods of spill control. Secondary containment for hazardous liquids and solids is required when liquids require spill control and when solids are stored in individual containers with a capacity exceeding 550 lbs. or the aggregate capacity of multiple containers exceeds 10,000 lbs. IFC Section 5004.2.2 provides some basic requirements for secondary containment and references—through IFC Table 5004.2.2—individual chapters for specific requirements based on material category.

Per the IBC, when weather protection for outdoor storage of hazardous materials complies with the requirements of Section 414.6.1, then the structure is still considered outdoor storage and does not need to meet the indoor storage requirements. Walls are permitted on one or more sides provided they do not cover more than 25% of the perimeter, and the overhead structure must be of noncombustible materials.

Submittal Documents

For occupancies that include the storage or use of hazardous materials, a report must be submitted to the building official that provides the following information:

• A listing of expected quantities of hazardous materials using the categories per IBC Tables 307.1(1) and 307.1(2). Each material should be broken down into quantities stored, used in open systems, and used in closed systems.
• A description of the methods of protection from the hazardous materials, such as control areas, sprinklers, barricades, venting, and any other method employed by the design team.
• Separate floor plans showing the locations of hazardous materials stored in vessels and used in systems. This is required only if hazardous materials are within a Group H occupancy.

Conclusion

High-hazard occupancies are complex uses and can challenge design professionals if they are not experienced in designing buildings containing hazardous materials. Nevertheless, the use of hazardous materials is very common; they are used in medical clinics and hospitals, manufacturing plants, research laboratories, aircraft and vehicle maintenance shops, and many other uses—many of which do not require a Group H classification. If hazardous materials are expected to be used on a project, and the design professional does not have the experience designing for hazardous material uses, then hiring a consultant may be well worth the additional fee.

_____________________________

¹  The IFC Development Committee is responsible for the definitions used in this article, so the IFC is referenced as the source for these definitions.  However, many of these definitions are also replicated in the IBC.

²  The IFC has identical tables, 5003.1.1(1) and 5003.1.1(2), respectively.  Furthermore, since the IFC is not a building code and provides requirements for hazardous material usage indoors and outdoors, it includes Table 5003.1.1(3) for outdoor control areas.

³  The grade plane is defined in the IBC.  It is essentially the average elevation of the finished ground level around the perimeter of the building at the exterior walls.

⁴  This is footnote ‘d’ in Table 307.1(1) and footnote ‘e’ in Table 307.1(2).

⁵  This is footnote ‘e’ in Table 307.1(1) and footnote ‘f’ in Table 307.1(2).

⁶  The terms flammable solid, flammable liquid, and combustible liquid are defined in the IBC and IFC.  Therefore, a nonflammable solid, a nonflammable liquid, and a noncombustible liquid would be those that do not meet the definitions of the former.

⁷  The IFC defines deflagration as an “exothermic reaction, such as the extremely rapid oxidation of a flammable dust or vapor in air, in which the reaction progresses through the unburned material at a rate less than the velocity of sound. A deflagration can have an explosive effect.”  For example, the explosion created by the ignition of  natural gas due to a leak is deflagration.

⁸  The IFC defines detonation as an “exothermic reaction characterized by the presence of a shock wave in the material which establishes and maintains the reaction. The reaction zone progresses through the material at a rate greater than the velocity of sound.  The principal heating mechanism is one of shock compression. Detonations have an explosive effect.”

NFPA 285: Flame Propagation in Exterior Walls

Late morning on a winter day, a contracting crew was up on the roof of a building performing welding and cutting on a steel fabrication that was to become a catwalk for a window washing system. The hot work, unfortunately, ignited adjacent polyurethane-coated foam plastic trim and the fire spread laterally and vertically down the exterior face of the building. The outcome of the January 25, 2008, fire at the Monte Carlo Resort and Casino in Las Vegas, Nevada, was a $100 million price tag for damage and lost business. Fortunately there were no deaths, but 17 people were sent to hospitals for injuries.

The Monte Carlo fire illustrates the growing problem with incorporating combustible foam plastics within exterior wall assemblies. Large continuous planes of combustible material allow a fire to spread quickly horizontally and vertically to other areas of a building. Due to this fire propagation potential, the International Building Code (IBC) requires wall assemblies that integrate combustible plastics and most recently combustible water-resistive barriers be tested in accordance with the National Fire Protection Association's (NFPA) standard 285, Standard Method of Test for the Evaluation of Flammability Characteristics of Exterior Nonload-bearing Wall Assemblies Containing Combustible Components.

NFPA 285 and the IBC

Even though the standard's scope applies to nonload-bearing walls as its title implies, the IBC's requirements for testing does not differentiate between load-bearing and nonload-bearing walls—all wall assemblies with combustible materials (with some exceptions) are required to be tested. The 2012 IBC includes six provisions where NFPA 285 testing is specifically required:

• Section 1403.5: For combustible water-resistive barriers in buildings over 40 feet in height of Type I, II, III, or IV construction. This is a new requirement in the 2012 IBC.
• Section 1407.10.4: For metal composite materials (MCM) used on buildings of Type I, II, III, and IV construction. Section 1407.11 of the IBC provides alternate conditions that do not require compliance with NFPA 285, such as using MCM not higher than 40 feet and having a fire separation distance of more than 5 feet. If the fire separation distance is 5 feet or less, then only 10% of the wall area can include MCM.
• Section 1409.10.4: For high-pressure decorative exterior-grade compact laminates (HPL) exterior wall coverings used on buildings of Type I, II, III, and IV construction. Section 1409.11 of the IBC provides alternate conditions that do not require compliance with NFPA 285, such as using HPL not higher than 40 feet and having a fire separation distance of more than 5 feet. If the fire separation distance is 5 feet or less, then only 10% of the wall area can include HPL. These are new requirements in the 2012 IBC.
• Section 1509.6.2: Combustible mechanical equipment screens used on buildings of Type I, II, III, and IV buildings.
• Section 2603.5.5: Exterior walls of buildings of Type I, II, III, and IV construction of any height incorporating foam plastic insulation, except for one-story sprinklered buildings.
• Section 2612.5: For fiberglass-reinforced polymer (FRP) exterior wall coverings. This section references Section 2603.5, which means NFPA 285 is required for Type I, II, III, and IV buildings that are more than two stories and higher. However, this section does offer two exceptions that would not require NFPA 285 testing.

Noticeably missing in the list of requirements above are exterior insulation and finish systems (EIFS). That is because EIFS were not directly addressed in the IBC until the 2009 edition. Prior to the 2009 IBC, EIFS were regulated by the foam plastic insulation requirements of Chapter 26. In the 2009 IBC, EIFS were directly incorporated into the code in Section 1408, which requires compliance with ASTM E 2586, Standard Specification for PB Exterior Insulation and Finish Systems. Since ASTM E 2586 requires EIFS to pass NFPA 285, Section 1408 essentially supplants the foam insulation requirements of Chapter 26 for EIFS.

The IBC has always referenced NFPA 285 for foam plastic insulation; however, Uniform Building Code (UBC) Standard 26-4, Method of Test for the Evaluation of Flammability Characteristics of Exterior, Nonload-Bearing Wall Panel Assemblies Using Foam Plastic Insulation, was permitted by the 2000 IBC and, prior to the IBC, the UBC. The 1997 UBC introduced UBC Standard 26-9, Method of Test for the Evaluation of Flammability Characteristics of Exterior, Nonload-bearing Wall Assemblies Containing Combustible Components Using the Intermediate-scale, Multistory Test Apparatus, which eventually became NFPA 285. The significant difference between UBC Standards 26-4 and 26-9 was that 26-4 was based on a full-scale mockup of the wall assembly, whereas 26-9 (and subsequently NFPA 285) is based on a smaller, intermediate-scale mockup.

Impact of NFPA 285 on Building Design

Since some form of fire propagation requirements for combustible materials in exterior walls have been in the code for over thirty years, why is it that design professionals are just now learning about NFPA 285? The answer is rather simple: energy codes are requiring higher performance from building envelopes, and the best method to improve thermal performance is providing continuous insulation. Continuous insulation interrupts the thermal bridging created by common exterior wall construction. When EIFS were introduced in the 1970s, they were the only foam plastic insulations used in this manner. When the codes caught up with the new technology in the 1980s and developed testing standards, EIFS manufacturers immediately sought testing for their systems. However, with few manufacturers and a limited number of common substrates, it was easier to test most, if not all, of the typical EIFS assemblies at the time.

It is important to stress that the NFPA 285 test is an assembly test and not a material component test. With the constant introduction of new exterior wall coverings, the implementation of the 'rain screen principle,' and the increasing requirements for improved thermal performance, the building exterior envelope suddenly became a very complex assembly with thousands of possible combinations, thereby making it cost-prohibitive for a manufacturer to test every probable wall assembly. If an assembly can be found that has passed the NFPA 285 test, then the assembly must be designed and built exactly as it was tested. Therefore, the designer must use all of the proprietary products that are indicated in the tested assembly—any change in the assembly, regardless of how minor, will require a new test.

With this wide variety of potential exterior wall assemblies to choose from, the design professional must now consider one of the following options to remain compliant with the building code:

• Design a building using Type V construction;
• Design a sprinklered building with only one story above grade plane;
• Design an exterior wall assembly that has no combustible materials;
• Design a building using MCM and HPL that is more than 5 feet from the lot line and is less than 40 feet in height and includes no foam insulation or combustible water-resistive barrier;
• Select a tested wall assembly from the few assemblies that are available; or,
• Design a wall assembly and have it tested.

Some of the options mentioned above may not be immediately available to the design professional due to a building's design program (i.e. size and types of spaces required), available site area, or project budget. For example, designing a 100,000 sq. ft. office building on a tight urban site will likely eliminate the first two options. The third option, although achievable, will require some additional research time on part of the design team; however, to obtain equal energy performance using noncombustible materials (e.g. mineral wool insulation) will require thicker wall assemblies that may pose some design challenges. The fourth option is probable, but the use of foam plastic insulation or combustible water-resistive barriers (both are common with these exterior wall coverings) may require testing anyway. Resorting to the fifth option will limit the number of material and assembly options on a designer's palette. Lastly, the project budget may eliminate the sixth option, since project-specific testing can be very expensive.

The NFPA 285 Test

As mentioned earlier, the NFPA 285 test is conducted on an intermediate-scale mockup. A mockup is an exact fabrication of a proposed assembly. For the NFPA 285 test, the mockup is attached to a test apparatus that consists of a three-walled, two-story structure with an overall height of 15'-8". Each story contains a test room—each having dimensions of 10 feet wide by 10 feet deep by 7 feet high. The apparatus is constructed of steel, concrete, and concrete masonry units. The interior wall and ceiling surfaces of the first story are covered with a layer of Type X gypsum board over ceramic fiber insulation. The floor of the first story is covered by two layers of gypsum board.

The mockup test specimen is constructed on the open face of the test apparatus or on a portable frame that is moved into place and attached to the test apparatus. The size of the mockup is 17'-6" high by 13'4" wide and must include a window opening approximately 30 inches high by 78 inches wide that is centered horizontally in relation to the first story test room's side walls. The sill height of the window opening must be 30 inches. Thermocouples, which are used to measure temperature, are attached to the exterior face of the mockup, the interior of the mockup assembly, and the interior face of the mockup at the locations indicated in the test standard. Thermocouples are also attached to the ceiling of the first-story test room.

The test procedure includes two burners: a fixed gas burner in the center of the first-story test room and a portable gas burner that is placed in the window opening. The room burner is ignited and must achieve a first-story room temperature of 1151 deg. F within the first 5 minutes. At that time, the window burner is ignited and both continue to burn for another 25 minutes for a total 30-minute test period and achieving an average first-story room temperature of 1648 deg. F.

After the test, the mockup is dismantled and visually observed. The assembly fails if flame propagation exceeds the limits indicated in the standard. Flame propagation is determined in three locations of the mockup: the exterior face of the assembly, core components of the assembly, and the areas beyond the first-story test room.

• Exterior face of assembly: Flame propagation is determined 1) if the flames reach a height of 10 feet or greater above the window opening, 2) if the flames extend laterally a distance of 5 feet or greater from the centerline of the window opening, or 3) if any of the thermocouples at the roof line record a temperature of 1000 deg. F or higher.
• Core components of assembly: Assemblies with wall coverings greater than ¼" thick, or ¼" thick or less with no air cavity, cannot have combustible components that exceed 750 deg. F at thermocouples near the assembly perimeter at the second-story test room. Assemblies with wall coverings ¼" thick or less and having an air space cannot have temperatures in the air cavity exceeding 1000 deg. F or in the insulation exceeding 750 deg. F at thermocouples near the assembly perimeter at the second-story test room.
• Areas beyond the first-story test room: Flame propagation is determined if flames on the exterior surface extend beyond the side walls of the apparatus or flames occur beyond the intersection of the wall assembly and the side walls of the apparatus. Assemblies with wall coverings greater than ¼" thick, or ¼" thick or less with no air cavity, cannot have combustible components that exceed 750 deg. F at thermocouples located in line with side walls. Assemblies with wall coverings ¼" thick or less and having an air space cannot have temperatures in the air cavity exceeding 1000 deg. F or in the insulation exceeding 750 deg. F at thermocouples located in line with side walls.

There are two other conditions that will also warrant a failing report for a NFPA 285 test. The first condition is when any thermocouple that is located within 1 inch of the interior wall surface at the second-story test room exceeds 500 deg. F. The second condition is when flames occur in the second-story test room.

The Future of NFPA 285 in the IBC

The 2015 IBC will likely include a reference to the 2012 edition of NFPA 285. There are some changes in the 2012 edition, which include expanded conditions of acceptance that may impact some assemblies previously tested under the 2006 edition.

For water-resistive barriers, the 2015 IBC will include some changes that will help relax the requirement for NFPA 285 testing for combustible barriers. Based on a public comment during the IBC final action hearings in 2012, Section 1403.5 will add the following three exceptions:

• Exception 1: "Walls in which the water-resistive barrier is the only combustible component and the exterior wall has a wall covering of brick, concrete, stone, terra cotta, stucco, or steel with thicknesses in accordance with Table 1405.2."
• Exception 2: "Walls in which the water-resistive barrier is the only combustible component and the water-resistive barrier has a Peak Heat Release Rate of less than 150 kW/m², a Total Heat Release of less than 20 MJ/m² and an Effective Heat of Combustion of less than 18 MJ/kg as determined in accordance with ASTM E 1354 and has a flame spread index of 25 or less and a smoke-developed index of 450 or less as determined in accordance with ASTM E 84 or UL 723. The ASTM E 1354 test shall be conducted on specimens at the thickness intended for use, in the horizontal orientation and at an incident radiant heat flux of 50 kW/m²."
• Exception 3: "Windows and doors and flashing for windows and doors shall not be considered to be part of a water resistive barrier for purposes of this section."

Unfortunately, the publication of the 2015 IBC is still a couple of years away with many jurisdictions likely not adopting it until a few years after that. However, using Section 104.11 for alternative materials, designs, and methods, a design professional could request a code modification allowing the use of the approved exceptions prior to the publication and adoption of the 2015 IBC.

Unlike assemblies tested by Underwriters Laboratories, which are included in its online certifications directory, the reports for successful NFPA 285-tested assemblies are retained solely by the manufacturer. Therefore, the design professional must seek out tested assemblies through manufacturers without the convenience of a directory of approved assemblies. Hopefully, some form of directory for NFPA 285-tested assemblies will be compiled by a professional, manufacturer, or trade association. With a consolidated directory of NFPA 285-tested assemblies, design professionals could easily select code-compliant exterior wall assemblies, thereby avoiding incidents such as the Monte Carlo fire, which, as it turns out, was not constructed of foam plastic materials tested per UBC Standard 26-4, the applicable standard at the time of its construction.

---

¹  Although the latest edition of NFPA 285 is the 2012, the 2006 edition is the one referenced in the 2012 IBC.  However, the first and second printings of the 2012 IBC indicate a “NFPA 285-11” edition, but an errata dated 02-27-13 was issued correcting the edition to the 2006.

²  Fire separation distance is the distance measured between the face of the building and the closest interior lot line, the centerline of a street, alley, or public way, or to an imaginary line between two buildings on the same property.  The distance is measure at right angles to the face of the wall.

³  In UBC editions prior to the 1994 edition, the standard referenced was UBC Standard 17-6.  The number change was the result of chapter restructuring in response to the efforts of the Council of American Building Officials’ (CABO) Board for Coordination of Model Codes (BCMC) to standardize the organization of the three model building codes.

High-Rise Buildings

Tall structures have been in existence for centuries.  The Great Pyramid of Giza, built in the 26^th Century BC, was as high as 480 feet high.  The Towers of Bologna, constructed in the 12^th Century AD, topped out at about 320 feet for the tallest tower.  Although these were tall structures, they did not perform the same functions that today’s modern high-rise does.  The purpose of the modern high-rise building is to maximize building area in the smallest lot area.  The modern high-rise rose to prominence when two significant developments were achieved:  steel frame construction and the safety elevator.

Steel frame construction allowed buildings of great height without the use of loadbearing walls, since this would have required thick walls at the base that would have rendered the lower stories useless.  Steel frame construction acts like a skeleton upon which the lighter weight building skin is attached.  The safety elevator provided a rapid means of travel to the upper floors without having to use stairs.  The “safety” aspect is a braking device that would stop the elevator cab should it drop uncontrollably from equipment or cable failure.

From a life safety perspective, the high-rise poses unique situations not found in buildings of lower height.  Regarding egress, most high-rise buildings have relatively small floor areas making the travel distance to an exit stairway well within the limitations of the International Building Code (IBC).  However, long travel down the stairs is slow compared to egress through corridors and exit passageways.  Additionally, the heights associated with high-rise buildings make it more difficult to fight fires at the extreme elevations.

How ‘High’ is a High-Rise Building? 
  
This discussion regarding building height leads to the prime question: at what height is a building considered a high-rise?  A high-rise building is defined in Chapter 2 of the IBC as a “building with an occupied floor located more than 75 feet (22 860 mm) above the lowest level of fire department vehicle access.”  Unlike the standard building height dimension regulated by the IBC, the height for determining a high-rise building is determined by two different points of measurement: 1) the lowest level of fire vehicle access and 2) the highest occupied floor (See Figure 1).

Regarding the bottom point of measurement, if a building is constructed on a site that has varying grade levels around its perimeter, the measurement is not to be taken at the grade plane as defined by the IBC.  Rather, the dimension is measured to the actual surface of the ground or pavement that is accessible by fire department vehicles.  This measurement point can be above or below the grade plane.

For the upper measurement point, this is taken at the floor level and not the overall height of the building.  For example, if a building has an overall height of 80 feet, but the highest occupied floor is at 70 feet, it is not considered a high-rise building.  However, if the building has an occupied roof (i.e. roof decks, but excluding occupancy for maintenance purposes), some building officials would consider the roof as an “occupied floor,” thereby making the roof and not the enclosed floor below the point of measurement. 

Knowing where to take the measurement is important, but why is the measurement limited to 75 feet?  To understand this, you have to understand firefighting capabilities.  Although platform and aerial ladder fire trucks have reaches that exceed 75 feet, geometry may factor into the actual reach capabilities of the fire department.  Although the measurement is to the ground level of the fire department access, there is no requirement for how close the access must be to the building beyond the International Fire Code (IFC) requirement that fire access roads extend to within 150 feet of all portions of a building’s first story.   Therefore, the farther the fire truck is from the building, the lower the height it can reach.  The Insurance Services Office (ISO), which rates fire departments, has set a maximum reach of 100 feet to achieve maximum points in this category.¹  This gives the fire department a 25-foot margin if they encounter differing circumstances at incident sites, such as the location of the fire lane from the building.

Special Requirements for High-Rise Buildings

Section 403 of the IBC establishes the minimum requirements for high-rise buildings.  This section starts off with a list of buildings that, by definition, are high-rise buildings but are considered exceptions to the special requirements.  These include airport traffic control towers, open parking garages, Group A-5 buildings, special industrial occupancies, and Group H-1, H-2, and H-3 occupancies.  This section adds supplementary requirements beyond the basic requirements in other sections of the IBC.  However, this section also modifies some basic requirements for high-rise buildings or exempts them from some basic requirements.

As a result of the September 11, 2001, attacks on the World Trade Center (WTC) in New York City, the IBC incorporated a number of revisions over time within the 2006, 2009, and 2012 editions—the majority of which were implemented in the 2009 edition.  These revisions were implemented to increase the protection of building elements and enhance the means of egress systems in high-rise buildings.  In the 2006 IBC, a specific distinction was made between two types of high-rise buildings:  those that are not greater than 420 feet in building height and those that are greater than 420 feet in building height.  You will notice that, unlike the definition of a high-rise building, this height is measured according to the IBC definition of building height, which is between the grade plane and the average roof height of the highest roof.

Construction Type and Fire-Resistive Construction

Based purely on Table 503 of the IBC, high-rise buildings must be of Type I construction.  However, with a sprinkler system, a Type IIA, Type IIIA, or Type IV building could become a high-rise building if an occupied floor (or occupied roof, depending on the building department’s interpretation) is more than 75 feet above the fire department vehicle access.² 

If a high-rise building is equipped with sprinkler control valves that have both supervisory initiating devices and water-flow initiating devices at each floor,³ then the fire-resistive ratings associated with the construction type could be reduced.  A Type IA high-rise building that is not greater than 420 feet is permitted to be constructed using fire-resistance ratings equal to that of Type IB construction, except that the fire-resistance rating of columns supporting floors cannot be reduced.  A Type IB high-rise building—except for Group F-1, M, and S-1 occupancies—is permitted to be constructed using the fire-resistance ratings of Type IIA construction.  For either of these two reductions, the use of the building height and area limitations for the original construction type are permitted.  For example, a Type IB, Group B high-rise building may reduce the fire-resistance rating of its building elements to that of Type IIA construction per IBC Table 601, but the height and area of the building is still limited to that of Type IB construction per IBC Chapter 5.

Although not specific to high-rise buildings, the definition of primary structural frame in the IBC was modified as a result of the National Institute of Standards and Technology’s (NIST) building code recommendations following its WTC research.  The definition stipulates that lateral bracing is part of the primary structural frame if it is essential to the vertical stability of the building—even if the bracing does not carry any gravity loads.  Therefore, if IBC Table 601 requires a 2-hour rating for the primary structural frame, then lateral bracing for high-rise buildings would be considered essential to the building’s vertical stability and would be required to have an equal fire-resistance rating.

The IBC has one other reduction and one increase for high-rise buildings relating to fire resistance.  The reduction applies to high-rise buildings not greater than 420 feet, and allows the fire barriers for vertical shafts—this does not include shafts for elevators and exit enclosures—to be reduced from 2 hours to 1 hour.  The increase applies to sprayed fire-resistant materials, and increases the minimum bond strength from 150 psf (IBC Section 1705.13.6), to 430 psf for high-rise buildings up to 420 feet, and 1,000 psf for high-rise buildings greater than 420 feet (IBC Table 403.2.4).

Means of Egress

Several changes and additions to the means of egress requirements have been introduced in the IBC for high-rise buildings.  Some of these new requirements were controversial and were opposed by organizations such as the Building Owners and Managers Association (BOMA). 

The most controversial requirement was an additional stairway for buildings more than 420 feet in height (IBC Section 403.5.2).  For example, a building with multiple stories and an occupant load of 500 or less for each story would be required to have a minimum of two exits from each story.  However, if that building exceeds 420 feet in height, then a third stairway would be required.  This is to overcome the problem encountered at the WTC in 2001, when occupants were egressing down the stairs while firefighters were trying to work their way up the same stairs.  Furthermore, if one exit is removed, the remaining exits must provide the total exit width calculated per Section 1005.1.  This additional stairway requirement applies to all applicable high-rise buildings in all occupancy groups except for Group R-2.

The exception to the additional stairway requirement is to provide an occupant evacuation elevator per IBC Section 3008.  See The Code Corner No. 38, “Elevators,” for a detailed discussion on occupant evacuation
elevators.

Also related to exit stairways is the remoteness requirement (IBC Section 403.5.1).  The remoteness requirement states that interior exit stairways be separated by a distance not less than 30 feet or ¼ of the overall diagonal of the building or area to be served, whichever is less.  If three or more exit stairways are provided, at least two shall comply with the remoteness requirement.  If interlocking stairs are provided, the stairs will be counted as a single exit stairway.

Per IBC Section 403.5.3, doors leading into exit stairways are permitted to be locked from the stairway side, provided that all doors can be unlocked—not unlatched—simultaneously upon a signal from the fire command center, which is discussed later in this article.  For stairways where doors are locked from the stairway side, a two-way communication system connected to a “constantly attended station” must be provided on the stairway side at every fifth floor.

Stairways serving high-rise buildings are required to be constructed as smokeproof enclosures per IBC Section 403.5.4, which references IBC Sections 909.20 and 1022.10.  Section 1022.10 establishes the basic requirements for interior exit stairways within smokeproof enclosures.  The smokeproof enclosure must be accessed through a vestibule⁴ unless the pressurization alternative is implemented.  The smokeproof enclosure must terminate at an exit discharge or a public way; however, it can be extended using an exit passageway.  To do so, the exit passageway must be separated from the smokeproof enclosure with a fire door and have no other openings other than the door to the exit discharge.  Other openings are permitted into the exit passageway provided it is accessed by vestibules like the smokeproof enclosure or is pressurized in the same manner as the smokeproof enclosure.  If the exit passageway is pressurized in the same manner as the smokeproof enclosure, then the fire barrier and fire door between the smokeproof enclosure and exit passageway may be eliminated.  Finally, the last exception permits the smokeproof enclosure to egress through areas on the level of exit discharge per IBC Section 1027.

Another requirement specific to high-rise buildings is the use of luminous markings for the egress path per IBC Section 1024.  The only occupancy groups to which this applies are A, B, E, I, M, and R-1.  This section explains in great detail what needs to be marked and how.  If the stairway egresses through areas on the level of exit discharge, such as a lobby, the markings are not required in those areas.

The last egress requirement for high-rise buildings is actually an exception.  IBC Section 1029 requires that Group R-2 occupancies be provided with emergency escape and rescue openings for all sleeping rooms in stories below the fourth story.  However, because of the added protection and safety measures required of high-rise buildings, IBC Section 403.5.6 exempts high-rise buildings from having these openings.

Structural Integrity

Structural integrity is a set of requirements that was introduced in the 2009 IBC as a result of the WTC investigations.  The structural integrity requirements, located in IBC Section 403.2.3, apply to interior stairways and elevators in high-rise buildings in Risk Category III or IV per IBC Table 1604.4 and all high-rise buildings that are more than 420 feet in height.  The intent of this category is to ensure that elevators and interior stairways stay intact following a significant impact to those elements. 

The Code Corner No. 41, “Gypsum Board Construction,” describes in greater detail the requirements for structural integrity for soft body impact.  Although that article focuses on gypsum board (the most susceptible material likely to be used for these elements), the requirements apply to any material that is not masonry or concrete, which are exempted from the requirements.  Additionally, any complete wall assembly that has been tested to Classification Level 3 for Hard Body Impact per ASTM C 1629, Standard Classification for Abuse-Resistant Nondecorated Interior Gypsum Panel Products and Fiber-Reinforced Cement Panels, is permitted to be used.

Fire Protection and Emergency Systems

A fire command center (FCC) complying with IBC Section 911 is required in each high-rise building.  The design professional can locate the FCC where it best suits the project, but the location must be approved by the fire official.  The FCC must be separated from the rest of the building using 1-hour fire barriers, horizontal assemblies, or both.  The size of the room must have a minimum area of 200 sq. ft. with a minimum dimension of 10 feet; therefore, a 20-foot by 10-foot room is the minimum requirement.  IBC Section 911.1.5 provides a complete list of features that are required for the FCC.  The layout of the FCC and its features must be approved prior to installation.

Standby and emergency power systems are required for specific loads indicated in IBC Sections 403.4.8 and 403.4.9, respectively.  The main difference between a standby power system and an emergency power system is that the emergency power system requires its own distribution system (i.e. wiring, conduit, panels, etc.)—the standby power system can share the main distribution system.  Standby power is required for elevators, ventilation and fire detection equipment in smokeproof enclosures, and power and lighting for the FCC.  Emergency power is required for exit signs, means of egress lighting, elevator car lighting, voice/alarm communication system, automatic fire detection system, fire alarm system, and electric fire pumps. The IBC specifically requires standby power generators that are located inside the building be separated from the rest of the building with 2-hour fire barriers, horizontal assemblies, or both.  However, since the National Fire Protection Association (NFPA) 110, Standard for Emergency and Standby Power Systems, is referenced by the IBC for both types of systems, then a room, separated as required for an indoor standby power generator, is also required for an indoor emergency power generator.⁵

It probably goes without saying that high-rise buildings are required to be equipped with an automatic sprinkler system.  IBC Section 403.3 requires a system complying with NFPA 13, except for parking garages and telecommunications equipment buildings.  For buildings over 420 feet in height, a second riser is required for each sprinkler system zone.  Furthermore, each riser must supply water to sprinklers on alternating floors.  This prevents large, continuous blocks of stories from being unprotected should one riser fail for any reason.  To maximize the survivability of the risers, risers must be located in stairways that are separated by a minimum of one-third the overall diagonal dimension of the building.

In addition to a sprinkler system, standpipe systems are also required for all high-rise buildings.  Since high-rise buildings are required to have a sprinkler system, a Class I standpipe is the minimum requirement per Exception 1 to IBC Section 905.3.1.  Hose connections are required at all floor levels above and below grade, and they shall be placed at intermediate landings between floors or as approved by the fire code official.  If the high-rise building has a heliport, helistop, rooftop gardens, or landscaped roofs, then the standpipe is required to extend to the rooftop.

Fire pumps for all high-rise buildings must be supplied by connections to two separate water mains located on two separate streets per IBC Section 403.3.2.  Two connections to the same main are permitted provided that the main has valves that can isolate a break and not interrupt the supply to no less than one of the connections.  The piping connecting the fire pump to the two connections must also be separate.  Connections and piping for each line must be sized so that each line can individually provide the required flow and pressure for the fire pump.  Lastly, the room containing the fire pump must be separated from the rest of the building by fire barriers and horizontal assemblies with a fire-resistance rating of not less than 2 hours.

Several types of alarm, notification, and communication systems are specifically mandated for high-rise buildings.  The first is a voice/alarm communication system, which shall operate upon activation of a smoke detector, manual alarm box, or sprinkler water-flow device.  The voice/alarm communication system must sound a tone that is followed by evacuation instructions.  The second is a smoke detection system, which requires detectors in mechanical, electrical, telephone, elevator, and similar type equipment rooms, as well as elevator lobbies.  Duct smoke detectors are also required in main return air and exhaust air plenums of air conditioning systems with a capacity greater than 2,000 cfm and connections to vertical ducts or risers connecting two or more stories.  The third and final system is a fire department communication system, which is wired and connects the FCC to the elevators, elevator lobbies, emergency and standby power rooms, fire pump rooms, areas of refuge, and exit stairways.

High-rise buildings, like any other new building, are required to have emergency responder radio coverage throughout the building per IFC Section 510.  This requires that a system be installed in a building that ensures adequate radio communications between emergency responders.  Exceptions allow a wired system if approved by the fire code official, no system if the fire code official determines the coverage is not needed, or the fire code official may allow an automatically activated system if it is determined that a continuously operating system would have a negative impact on the normal operation of the building.

Smoke Removal

Another provision added to the IBC in the 2009 edition is the requirement to provide mechanical or natural ventilation.  The intent of this requirement is to provide a means for firefighters to expel the smoke after a fire event without requiring a full smoke control system that is specified in IBC Chapter 9.  The requirement (IBC Section 403.4.7) identifies three methods:  1) manually operated windows or panels, 2) mechanical air equipment, or 3) an alternate method.

The first method requires easily identifiable windows or panels to be located around the perimeter of the building at 50-foot maximum intervals.  The area of the openable units shall be based on 40 sq. ft. for every 50 feet of building perimeter.  Thus, if a building has a 300-foot perimeter, it will need to provide a minimum of 6 windows or panels with each window or panel providing a minimum of 40 sq. ft. of openable area.  There are two exceptions that modify this requirement.  The first exception applies to Group R-1 buildings that have sleeping units or suites located along the exterior wall.  This exception allows each sleeping unit or suite to provide an operable venting unit having an area of 2 sq. ft. in lieu of the main requirement.  The second exception allows fixed windows, but the glass must be able to be easily removed by breaking or other means to achieve the required area.

The second method allows the use of mechanical air-handling equipment to exhaust the smoke directly to the exterior.  The mechanical equipment must provide a minimum of one air change every 15 minutes.  For example, if a floor has a volume of 55,500 cubic feet, then an exhaust system that provides a minimum airflow of 3,700 cfm is needed (55,500 cubic feet ÷ 15 minutes).

The third method allows an alternative method that is approved by the building official.  If a building or a portion of a building is provided with a smoke control system in accordance with IBC Section 909, the building official may allow that system to be used instead of the less sophisticated methods described above.

The Future

It is ironic that today’s modern model life safety codes were developed as a result of a high-rise fire.  In 1911, a fire occurred on the eighth floor of the ten-story Asch Building in New York City that left 146 occupants dead.  Today, that building is called the Brown Building and is a part of the New York University campus in Greenwich Village.  The fire, better known as the Triangle Shirtwaist Factory fire, was considered the deadliest building disaster in New York until the WTC collapse 90 years later.

The NFPA, after the Triangle Shirtwaist Factory fire, worked towards improving the life safety aspect of buildings and developed the Building Exits Code in 1927, which would over time become the NFPA 101, Life Safety Code.  Also in 1927, the International Conference of Building Officials enacted the first Uniform Building Code, which incorporated construction and life safety requirements.  Although a model building code did exist prior to 1911 by the National Board of Fire Underwriters, its focus was preventing collapse and limiting structural damage, and not protection of life safety.

Like the Triangle Shirtwaist Factory fire, the WTC tragedy instigated sweeping changes to building and life safety codes with a greater emphasis on high-rise buildings.  Even though many requirements have been added to the IBC and other codes based on the recommendations of NIST, not all of the recommendations have been adopted.  Some of the proposals still under consideration include requiring buildings over 420 feet high to survive a complete burnout with only minor structural failure, requiring buildings not to experience a collapse that is disproportionate to the initiating failure (i.e. progressive collapse, such as that experienced by the WTC), and requiring a video surveillance system in exit stairways, elevator lobbies, elevator hoistways, and elevator equipment rooms for emergency responder situational awareness.  These proposals may or may not be included in future editions of the IBC, but there will likely be other events that will trigger new changes, and the cycle will continue.

---

¹  The measurement is to the roof and not the highest occupied floor level.  If a community does not have a building with a roof height greater than 100 feet, then they will award maximum points if the fire department can reach the height of the highest building in the community.  The ISO does not factor in the distance the apparatus is from the building; therefore, a straight up vertical reach that meets the minimum height satisfies the ISO requirement.

²  These construction types have a maximum building height of 65 feet.  With a sprinkler system, the height can be increased to 85 feet, which means a floor could possibly be located above 75 feet without exceeding the maximum number of stories if large floor-to-floor heights are used.

³  Supervisory initiating devices monitor the status of critical operating features of an automatic sprinkler system to ensure proper operation when needed.  Water-flow initiating devices send a signal to the fire alarm system when they detect water moving through an automatic sprinkler system due to an open sprinkler head.

⁴  In lieu of a vestibule, an open exterior balcony may be used.  However, for high-rise buildings this may be an unlikely option to consider, especially for stories at great heights.

⁵  NFPA 110 requires that an indoor Level 1 system be enclosed in a room separated from the rest of the building with 2-hour construction.  A level 1 system is defined by NFPA 110 as a system that “could result in the loss of human life or serious injuries.”  The explanatory information for NFPA 110 indicates that the loads required by the IBC are considered those applicable to a Level 1 system.

Gypsum Board Construction

Gypsum board has been an important part of the construction industry for more than 100 years.  Its humble beginnings started in the late 1800s as “Sackett Board,” named for Augustine Sackett, one of the inventors of the early gypsum product.  Sackett Board consisted of Plaster of Paris between two layers of felt paper.  The board was 1/4 inch thick and 36 inches square with exposed edges.  Although not suitable as a finish product as is today’s gypsum board, Sackett Board made an excellent base for gypsum plaster.  In 1910 the evolution of gypsum board took another step forward when a process for wrapping the exposed edges was implemented in manufacturing.  This was followed shortly by the replacement of felt paper with a true paper-based facing.  Over the next 40 years other developments in gypsum board were introduced, such as air-entrainment to make the board lighter, exterior wall and roof sheathing, and Type X fire-resistant board.

Gypsum board is frequently called “drywall,” a term whose origin has been lost over time, but was likely used to differentiate it from the “wet” gypsum plaster method.  Other terms have also worked their way into the gypsum board vernacular, such as “Sheetrock” (a brand name for gypsum board produced by United States Gypsum), and “plasterboard” (commonly used in Europe, Australia, and New Zealand).  ASTM C 11, Standard Terminology Relating to Gypsum and Related Building Materials and Systems, considers gypsum board to be “the generic name for a family of sheet products consisting of a noncombustible core primarily of gypsum with paper surfacing”; thus, gypsum board will be used throughout this article.

Gypsum Board Materials

In the International Building Code (IBC), gypsum board or gypsum wallboard are mentioned numerous times—primarily regarding fire-resistive construction—but the basic requirements for gypsum board, regardless of where gypsum board is mentioned, are located in Chapter 25.  Section 2506 requires that gypsum board materials comply with the material standards in Table 2506.2.  For standard gypsum board products, the table lists ASTM C 1396, Standard Specification for Gypsum Board, which includes the following:

• Gypsum Wallboard:  A gypsum board defined in ASTM C 11 as being “used primarily as an interior surfacing for building structures.”

• Predecorated Gypsum Board:  A gypsum board with a factory-applied decorative surface or coating.

• Gypsum Backing Board:  A thin, 1/4-inch to 5/8-inch, gypsum board used as backing for gypsum wallboard, acoustical tiles, or other dry cladding.

• Gypsum Core Board:  A thick, 3/4-inch to 1-inch, laminated gypsum board used for solid or semi-solid partitions.

• Gypsum Shaftliner Board:  A gypsum board, usually 1-inch-thick, used in specialized shaft assemblies.

• Water-Resistant Gypsum Backing Board:  A gypsum board with a water-resistant core used as a backing material to ceramic and other types of tile.

• Exterior Gypsum Soffit Board:  A gypsum board used for exterior soffits that are protected from liquid water.

• Gypsum Sheathing Board:  A gypsum board suitable for use as a backing for exterior wall coverings and which consists of a water-resistant paper and may have a water-resistant core.

• Gypsum Base for Veneer Plaster:  A gypsum board used as a substrate to a thin coating of specialized plaster.

• Gypsum Lath:  A gypsum board used as a substrate for gypsum plaster in lieu of metal or board lath.

• Gypsum Ceiling Board:  A gypsum board designed for ceiling applications where water-based finishes are applied.

The IBC Table 2506.2 also identifies other gypsum-based board materials along with the required material standards.  These include:

• Fiber-reinforced gypsum panels per ASTM C 1278.  These panels consist of gypsum with cellulose fibers for strength and have no paper facing.

• Glass mat gypsum backing panel per ASTM C 1178.  These panels consist of a gypsum core surfaced with a fiberglass mat that is embedded or partially embedded in the core and has a water-resistant coating applied to one surface.

• Glass mat gypsum panel per ASTM C 1658.  These panels are similar to the backing panels, but are suitable to receive a decorative finish.

• Glass mat gypsum substrate per ASTM C 1177.  These panels are used for exterior sheathing and consist of a water-resistant gypsum core surfaced with a fiberglass mat that is embedded or partially embedded in the core.

Joint treatment materials, such as joint compound and joint tape, are required to conform to ASTM C 475, Standard Specification for Joint Compound and Joint Tape for Finishing Gypsum Board.  Joint tape may consist of paper or fiberglass mesh; self-adhered tapes are also permitted.  Gypsum board accessories must comply with ASTM C 1047, Standard Specification for Accessories for Gypsum Wallboard and Gypsum Veneer Base. 
Accessories include cornerbeads, edge trims, and control joints fabricated from zinc-coated steel, zinc, and ABS and PVC plastic.  Metal accessories may include paper flanges.

Fasteners for attaching gypsum board to steel framing shall conform to either ASTM C 954 or ASTM C 1002 for steel screws. The former standard is for screws used to attach gypsum board to steel studs having a thickness of 0.033 to 0.112 inch, which are commonly referred to as cold-formed steel framing.  The latter standard applies to screws used for attaching gypsum board to nonstructural steel studs.  For attachment to wood framing, screws
complying with ASTM C 1002 or nails complying with ASTM C 514 are used.  Standard wood fasteners complying with ASTM F 547 or ASTM F 1667 are also permitted by the IBC for attaching gypsum board to wood framing.  If adhesives are used for securing gypsum board to wood framing, the adhesive must comply with ASTM C 557, Standard Specification for Adhesives for Fastening Gypsum Wallboard to Wood Framing.

Gypsum Board Installation

The IBC provides few requirements regarding the installation of gypsum board.  Instead, the IBC relies on the provisions of ASTM C 840, Standard Specification for Application and Finishing of Gypsum Board or Gypsum Association’s GA-216, Application and Finishing of Gypsum Board.  The ASTM standard addresses materials and preparation in addition to the various methods of attaching gypsum board.  Although both standards include provisions for stapling gypsum board to wood studs in two-ply installations, this method is not permitted by the IBC, since Section 2508.1 only permits the materials listed in Table 2506.2, which does not include staples.  On the other hand, IBC Section 2306.3 provides criteria for stabling of gypsum board used as shear walls in wood frame construction.

ASTM C 840 provides eleven different systems for application of gypsum board, including typical interior installations on wood and steel stud framing, adhesive application to interior masonry and concrete, and installation for exterior soffits and other protected areas.  Curved installations are also addressed using the two methods of moistening the board or cutting the back side.  GA-216 includes applications similar to those in ASTM C 840, but it also includes installations for solid gypsum panel partitions and installations over existing interior walls and ceilings.

General installation requirements common to both standards include minimum fastener length, cutting of gypsum board, location of control joints, fastener spacing, and fastener drive depth.  Another commonly overlooked requirement within both standards is that the bottom edge of gypsum boards be at least 1/4-inch above the floor surface—gypsum board is not permitted to be in contact with the floor surface.

The IBC requires in Section 2508.4 that gypsum board used in a fire-resistance-rated construction have the joints treated with tape and compound and that fastener heads be treated with compound.  However, the treatment is not required if one of the following conditions exists:

• The joints and fasteners will be covered with a decorative treatment that would provide similar protection, such as wood paneling and acoustical finishes.

• The joints occur over wood framing members.

• Square- or V-edged gypsum board used as backing or sheathing.

• Multi-layer applications where the joints between layers are offset.

• Assemblies that are tested without treated joints.

IBC Section 2508.2 requires gypsum sheathing when gypsum panels are used as a substrate for exterior wall coverings.  Installation of gypsum sheathing shall comply with ASTM C 1280, Standard Specification for Application of Gypsum Sheathing.  According to ASTM C 1280, gypsum sheathing cannot be left exposed for more than 30 days, after which it must be covered by an exterior wall covering or water-resistive barrier.  Requirements for water-resistive barriers are provided in IBC Section 1404.2.  Some manufacturers advertise products that can be left exposed for much longer periods of time, but to do so may likely require approval by the building official using the manufacturer’s test data or an acceptable evaluation report.

Interior and exterior gypsum board that is part of a fire-resistance-rated assembly or a shear assembly is required to be inspected by the building official per IBC Section 110.3.5.  The inspection must take place after the installation of the gypsum board, but prior to the installation of any cladding or decoration, including taping and finishing of joints and fasteners. 

Application Limitations

In Section 2509, the IBC limits the use of certain gypsum board types in areas subject to moisture.  Where wall tile is used in tub or shower areas or as wall and ceiling panels in shower areas, the only gypsum-based panel product permitted is glass mat water-resistant gypsum backing board per ASTM C 1178.  Cement-based panels complying ASTM C 1288 or ASTM C 1325 are also permitted, but are not considered gypsum products.

In water closet compartments, standard water-resistant gypsum backing board per ASTM C 1396 is permitted as a base for tile while other types of gypsum board, such as gypsum wallboard, is permitted as a tile base in other wall and ceiling locations.  Water-resistant gypsum backing board, however, cannot be used in areas where it will have direct exposure to water or continuous high humidity.  Additionally, on ceilings, 1/2-inch panels cannot be used when the framing spacing exceeds 12 inches or for 5/8-inch panels when the framing spacing exceeds 16 inches.  The IBC also does not permit the use of water-resistant gypsum backing board in shower and bathtub compartments when installed over a vapor retarder, which will be interpreted to mean all water-resistant board, even the glass mat type.

Per IBC Section 403.2.3, interior exit stairways and elevator hoistways constructed of gypsum board in high rise buildings in Risk Category III or IV per IBC Section 1604.5, or all high rise buildings more than 420 feet in height, must meet certain structural integrity requirements.  Assemblies surrounding stairways and elevator hoistways must conform to Classification Level 2 for Soft Body Impact per ASTM C 1629, Standard Classification for Abuse-Resistant Nondecorated Interior Gypsum Panel Products and Fiber-Reinforced Cement Panels.  The face of these assemblies not exposed to the interior of the assemblies is required to be constructed according to one of the following assemblies:

• A minimum of two layers of impact-resistant board complying with Classification Level 2 for Hard Body Impact per ASTM C 1629.

• A minimum of one layer of impact-resistant board complying with Classification Level 3 for Hard Body Impact per ASTM C 1629.

• Multiple layers of any material when tested together complying with Classification Level 3 for Hard Body Impact per ASTM C 1629.

Gypsum Board Myths

There are many myths surrounding gypsum board, but the most common that this author has encountered are the following two:

Myth #1 – Gypsum board is considered a combustible material because of the paper facing. 

Chapter 7 of the IBC establishes the minimum criteria that must be met for a material to be considered noncombustible.  Gypsum board is considered a composite material, thus it is required to meet the testing requirements indicated in Section 703.5.2.  Per that section, the structural base (i.e. gypsum core) must pass the test of established in ASTM E 136, Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750°C, which it does.

In a composite material, the structural base may be covered with a surfacing not more than 5/8-inch thick which has a flame spread index of not more than 50 when tested per ASTM E 84, Standard Test Method for Surface Burning Characteristics of Building Materials, or UL 723, Test for Surface Burning Characteristics of Building Materials.  The paper facing or other facing type on gypsum board has flame spread indices that vary but are less than 50, since the ASTM standard for gypsum board requires a flame spread index of 25 or less.  Thus, gypsum board products are considered noncombustible materials per the IBC.

Myth #2 – The color of the gypsum board facing indicates the type of gypsum board.

The facings used on gypsum board products are not part of a standardized identification system for gypsum board.  Some products are referred to as “greenboard” (for mold- or moisture-resistance) or “blueboard” (for plaster base) because of the specific characteristics of the board facings, but this is not typical of all gypsum-based products.  For the most part, the color is a branding initiative on the part of manufacturers to make their products readily identifiable as their products on a project site.

Conclusion

There are many gypsum board products available that have not been mentioned in this article, mainly because the building code does not require or regulate them beyond the minimum requirements discussed.  These products include:

• Type X gypsum board has a special core that gives 5/8-inch board a 1-hour fire-resistance rating or 1/2-inch board a 3/4-hour fire-resistance rating, when applied parallel to wood studs at 16 inches on center and tested per ASTM E 119, Standard Test Methods for Fire Tests of Building Construction and Materials.

• Type C gypsum board has improved fire-resistance over Type X board, but is manufactured with a proprietary core that differs with each manufacturer and has varying levels of performance.  Assemblies using this type of board are tested per ASTM E 119 or UL 263, Fire Tests of Building Construction and Materials.

• Foil-backed gypsum board has a foil backing which functions as a vapor retarder.

• Flexible gypsum board is a 1/4-inch-thick panel specifically designed for application to curved surfaces.

• Abuse-resistant gypsum board is used in areas not previously discussed where the board is frequently subject to damage from abrasion or impact, such as in corridors of schools and factories.

• Mold-resistant gypsum board is board complying with the basic requirements of ASTM C 1396, but is also tested for mold growth per ASTM D 3273, Standard Test Method for Resistance to Growth of Mold on the Surface of Interior Coatings in an Environmental Chamber. A rating of 10 (“totally absent of disfigurement by particulate matter”) per ASTM D 3274, Standard Test Method for Evaluating Degree of Surface Disfigurement of Paint Films by Fungal or Algal Growth, or Soil and Dirt Accumulation, is reported by manufacturers that provide these panels.

• Acoustically enhanced gypsum board (also called “acoustic” or “sound-deadening” gypsum board) provides improved resistance to sound transmission.  These products typically consist of a viscoelastic membrane sandwiched between two gypsum board layers.

Many of the gypsum board products available on the market provide more than one of the gypsum board characteristics listed above. For example, some acoustically enhanced gypsum boards also provide mold resistance.  Manufacturers will continue to improve their products and devise new gypsum products as building science expands.  The building code may also evolve after these new products hit the market, but in the meantime, the basic requirements of the building code apply.  However, the IBC does allow installation of approved materials as provided for in Section 2501.1.3.

Construction Documents Revisited

The topic of construction documents was addressed in a previous article of The Code Corner¹.  However, the message of that article was the broad subject of construction documents by building code definition and did not broach methods of how to actually communicate code-related information in the documents.  This article and a companion article in RLGA’s Keynotes² series will expand on the previous Code Corner article by introducing methods to better communicate building code compliance within the drawings and specifications.

Plan reviews can take a few days up to several weeks or months depending on the size of the project.  For design professionals, knowing the timeframe for a typical plan review in the jurisdiction of the project is important—it should be considered when developing the design schedule to ensure a realistic date for permit approval.  Even though the jurisdiction may indicate a long review time, the entire review period is not devoted to a single set of construction documents—plans examiners are reviewing multiple projects at the same time.  Thus, plans examiners can only afford so much time to review a set of construction documents submitted for permit, and the easier it is for the plans examiner to review a set, the quicker the review will be completed.

Consolidate Code-Related Information

Probably the most time-consuming part of a plan review is finding all the pieces of information in the construction documents that support compliance with the building code.  The International Building Code (IBC) specifies what information is required, but it does not specify how that information should be indicated.  The plan review process can be streamlined by summarizing detailed construction drawing information on code-specific sheets near the front of the set of documents.

Some jurisdictions may expand upon the basic requirements found in the IBC by establishing a required format for presenting code-related data.  An example of this is North Carolina’s “Appendix B.”  Section 104.1.1 of the North Carolina Administrative Code requires that “Construction specifications and drawings, including Appendix B of this code” shall be submitted.  The form itself states that the data in the Appendix be reproduced “on the building plans sheet 1 or 2.”  This standardizes the location and organization of code information, which makes it easier for designers and plans examiners alike.

However, not all jurisdictions are like the State of North Carolina, so this article attempts to bridge that gap by providing guidance on how to show code information in a set of construction documents.  The United States National CAD Standard version 5 (NCS) includes a module specifically addressing code information on drawings.  NCS Module 8, “Code Conventions,” provides recommendations on location, format, and graphic representation of some code-related information.  Although the NCS recommendations establish a good baseline from which to start, they do not provide detailed examples of how to address other significant code information required in construction documents.

Code Data on Drawings

If you are a design professional, you have probably designed a project for an existing building, whether it was an alteration or addition.  If you were lucky, the owner had record drawings of the original construction—if you were really lucky, those drawings had detailed code information.  How nice it would be to look at a set of record drawings and be able to determine what codes were applicable and to follow the design team’s code application process.  That is exactly what the plans examiner is looking for in a set of documents.

The code data sheet (or the first sheet if more than one code data sheet is provided) should provide basic code data, such as the adopted codes applicable to the project, the construction type, the installation of a fire sprinkler system or not, the storage or use of hazardous materials, and the applicable occupancy groups (See Figure 1).  If the building is a mixed occupancy, identify the method that will be applied: separated, nonseparated or a combination of both.  Applicable incidental uses per Section 509 may be listed, as well as accessory occupancies that comply with Section 508.2. If special requirements of Chapter 4 and Section 510 apply, those can be identified with a brief description.  Another item to include in this portion of the code data is a listing of any applicable reference documents, such as approved reports, variances, and code modifications.

Figure 1 - Basic code data showing information such as a list of adopted codes, construction type, occupancy groups, and the presence of a sprinkler system. Note the inclusion of an approved report as a reference document.

Following the code basics on the same sheet should be detailed information on how the building complies with the broader requirements of allowable height and area (See Figures 2 and 3).  The height and area data should include actual floor areas and building height and allowable height and floor areas per Table 503.  If increases to allowable areas and height are permitted, show the calculations and compare the allowable numbers to the actual numbers to show compliance. If the building has more than one story, calculations should show that each story is within the allowable area and that the overall building is within the total allowable building area.  Since the intent of the code data information is to explain the designer’s code application process, each step of all calculations should be shown.  This allows the plans examiner to follow step-by-step how the building complies.

Figure 2 - The above example shows the presentation of height and area requirements for a building that uses the nonseparated occupancies method. Notice that the most restrictive occupancy group is identified.

Figure 3 - The above example shows the allowable area calculations for another building that uses the separated occupancies method. Allowable area calculations are provided for each occupancy group and the actual-to-allowable ratios are calculated for each floor.

In regard to the allowable area increase for frontage, the open space widths and perimeter lengths used to calculate the value of W per Section 506.2.1 should be identified on a site plan—preferably a site plan prepared specifically for relaying code information.  The open space widths should be identified as such so as not to confuse them with fire separation distances, since these are not necessarily the same.

Since the building height is measured from the grade plane, the grade plane elevation should be calculated and shown on the code sheets if the grade surrounding the building is not relatively level.  The grade plane calculation should be included in the same area with the building height calculations.  The grade elevation points around the building that are used to determine the grade plane should be identified on the code-related site plan mentioned above.

The next section of code data is the fire resistance criteria for the building.  This section does not specifically identify locations for fire-resistive construction in the building (that will be covered later), but is provided to show that the designer understands the fire-resistive requirements of the code.  This section will essentially replicate Tables 601 and 602 as they apply to the construction type and occupancies used by the building.  This section should also include fire-resistive requirements for specific applications and uses, such as exits, shafts, corridors, incidental uses, control areas, and fire areas, to name a few.  To ease the plan review process, references to specific sheets and details can be provided that show specific construction and materials used.

In the same category as fire-resistive construction, but deserving special attention, are the requirements for exterior wall opening protection.  Unlike openings in fire-resistive wall and horizontal assemblies, which are prescribed based on an assembly’s type and rating, exterior wall openings have area limitations based on fire separation distance³.  Like open space for a frontage increase, the site plan needs to show fire separation distances for all sides of the building—especially if the distances are less than 30 feet.  The fire separation distances are then used in calculations in this section of the code data to determine the allowable areas of protected and unprotected openings per floor.  Comparisons of actual opening areas to allowable opening areas should be provided to show compliance.

The next section, means of egress, is probably the most complicated.  Means of egress can be shown on the code data sheets in one of three ways:  in tabular form, graphically on the drawings, or a combination of both.  The combination method probably provides the best means of describing egress compliance, since number-based data are best shown in a table while egress paths and distances are best shown on the floor plans.  Regardless of the method used, the following information should be present: occupant load of each space, the number of exits required and provided, exit width required and provided, travel distances, and lengths of common paths of egress travel.  Graphic representation of egress on the drawings is discussed later in the article.

Plumbing fixtures are another code requirement that should be summarized in the code data sheet.  Minimum plumbing fixture counts are determined using the occupant load determined for the building⁴ (See Figure 4) and should be compared to the actual fixture count provided in the design (See Figure 5).  If using the urinal substitution for fixtures in male restrooms, show the number within each restroom.

Figure 4 - Example table on how to show plumbing fixture calculations to determine minimum number of required fixtures. This example only shows the male requirements. A similar table is provided for female fixtures.

Figure 5 - Example table comparing the required minimum number of fixtures to those provided. Breaking the provided numbers down by each restroom helps the plans examiner locate the fixtures in the drawings. Note the column for urinals. Another column could be added to provide this calculation.

Another code requirement often overlooked in the designer’s code data sheets is the calculation for required portable fire extinguishers.  If fire extinguishers are required per Section 906.1, then the calculations determining the size and minimum number of required fire extinguishers (See Figure 6) should be provided⁵.  To confirm compliance, indicate the number of extinguishers provided and show the location for each on the floor plans.  If not readily apparent, travel distances to the fire extinguishers can be shown on the floor plans.

Figure 6 - Example showing one method on how to provide calculations for determining the size and quantity of portable fire extinguishers. Take note that the expected fire hazard (“Ordinary”) is indicated.

If the jurisdiction has adopted an energy code, the code data sheets can be called into service to provide the required information.  The type of information to be provided in the construction documents can be as simple as the required information per Sections C103.2 and R103.2 of the International Energy Conservation Code (IECC) for commercial and residential projects, respectively.  Another approach is to reproduce a copy of a report provided by applications such as COMcheck™ for commercial projects and REScheck™ for residential projects (See Figure 7)⁶.  These reports can be inserted into the code data sheets or submitted as a separate document.  However, providing the information in the code data sheets increases the chance that the energy compliance data will be available for future reference as a record document.

Figure 7 - Example of an “Envelop Compliance Certificate” produced by the COMcheck™ program. Many jurisdictions that have adopted an energy code will accept these certificates as verification of compliance.

Other code-compliance information specific to a project can also be provided in the code data sheets such as calculation of smoke vent area for stages, compliance with minimum emergency escape and rescue window area, and calculation of refuge area for horizontal exits.

Graphically Shown Code Data

As previously mentioned, some code data are better shown graphically in drawings than in notes or tables—a variation of the old adage that “a picture is worth a thousand words.”  The drawings used for code purposes should be tailored to that specific use—extraneous drawing information not applicable to code purposes should be deleted or, for CAD drawings, have unnecessary layers turned off.

Location of fire-resistive construction can be shown on the plans through the use of special line types.  The NCS recommends a bold line with one, two, or three diamonds to indicate 1-, 2-, or 3-hour wall construction.  However, this method falls short of providing complete information about the wall:  is it a fire partition or a fire barrier?  Additional information can be added to the line types to provide the necessary information (See Figures 8 and 9).

Figure 8 - Line type legend for fire-resistive wall construction. The X by the diamonds is replaced by one of the descriptors that describes the appropriate type of fire-resistive construction.

Figure 9 - Application of the fire-resistive wall line types in a code-specific floor plan.

If fire-resistive construction is used to divide the building into smaller fire areas, then the fire areas can be labeled with an identifier (e.g. “Fire Area 1”), most restrictive occupancy group, and floor area.  The floor area can be tied to calculations for allowable area, fire sprinkler requirements (to show that a sprinkler system is not required), or any other code requirement that is based on fire area size. 

For buildings storing or using hazardous materials, control areas can be shown on the plans, similar to fire areas, along with the separating fire-resistive construction.  Each control area can be graphically shown with an identifier that ties each control area to a table listing hazardous materials proposed for the control area with allowable and actual quantities.

Fire separation distances and open space distances (used for the value of W in calculating frontage increases) may be different than building location dimensions typically shown on architectural and civil drawings.  Fire separation and open space dimensions are measured perpendicular to the building face and not perpendicular to the lot line; therefore, if the building is not square with the surrounding lot lines, separate dimensions should be shown to indicate these dimensions (See Figure 10).

Figure 10 - Portion of a code-specific site plan showing dimensions for open space ("W") and fire separation distance ("FSD"). The building under consideration is to the bottom. Note that the dimensions are measured perpendicular to the face of the building.

Travel distance and common path of egress travel distance can also be shown graphically on the plans (See Figure 11).  The advantage of showing the distances on the plans is that it demonstrates for plans examiners how the distances were measured⁷.

Figure 11 - Portion of a code-specific floor plan showing travel distance and common path of egress travel distance. Also note the dimension for the overall diagonal of the space (and the minimum required exit separation) and the dimension between the exit and exit access stairway.

Tying it All Together

The key to having a successful set of code data sheets is to provide as much information about the project’s code compliance up front in the set to avoid having the plans examiner seek the information within the bulk of the remaining drawing sheets.  However, replicating in the code data sheets some drawings that are located in other areas of the construction documents, whether modified for their code use or not, may lead to problems.  Duplicate information in the construction drawings increases the chance for errors or conflicting information.  The design professional should weigh this increased risk against improving the readability of the documents by the plans examiner.

Considering the Construction Specifications Institute’s principle of “Say it once and in the right place,” the code data sheets can be used as a kind of index—directing the plans examiner to other locations in the construction documents to find code information.  Using interior finishes as an example, the code data sheet can state the minimum requirements per the code and then reference the Room Finish Schedule for locations of finish materials, which could further state specific paragraphs in the specifications that specify required classifications for finish materials.

 Referencing drawings that are further in the set of documents can be used to corroborate code data sheet information.  For example, if the code data sheet indicates that “Stairway No. 1” has a width of 54 inches, it can be added to “see Stair Plan 3, Sheet A-402” for actual dimensions.

Since a plans examiner’s allotted review time is limited and if the evidence of compliance is not readily apparent in the construction documents, you can be assured that comments will be generated.  Information that may have addressed the comment may be in the documents, but if the information is not readily apparent, it may be overlooked.  On the other hand, if a noncomplying element is missed during plan review because it was not discernible in the documents, it may be caught by the building inspector during construction, which may be more difficult (and sometimes costly) to resolve at that time than during plan review.  Design professionals can help themselves, plans examiners, and the plan review process by taking some additional drawing and specification measures that could shorten the review time and reduce the number of comments.

---

¹   See The Code Corner No. 25 “Construction Documents,” June 2007.

²   See Keynotes No. 12 “Specifying for Code Compliance,” available in September 2012.

³   See The Code Corner No. 35 “Openings – Part 2,” Spring 2011.

⁴   See The Code Corner No. 33 “Calculating Plumbing Fixture Counts,” Fall 2010.

⁵   See The Code Corner No. 31 “Portable Fire Extinguishers,” Spring 2010.

⁶   The COMcheck™ and REScheck™ programs are developed by the U.S. Department of Energy through the Building Energy Codes Program and are available for free at http://www.energycodes.gov/. The programs provide energy performance compliance based on ICC (International Code Council), ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers), and a variety of jurisdictional energy codes.

⁷   See The Code Corner No. 29 “Travel Distance,” September 2009.

Glass and Glazing

According to the Glass Manual, published by the Glass Association of North America (GANA), glass has been around for more than 4,000 years.  Glass allows daylight in and allows building occupants to view the outside world while still maintaining an envelope to separate inside from outside.  However, the use of glass in buildings presents issues that must be addressed, such as energy efficiency, fire protection, and life safety.  The International Building Code (IBC) covers all three of these areas.

The IBC establishes energy efficiency requirements through its reference to the International Energy Conservation Code (IECC) in Chapter 13.   For fire protection, Chapter 7 covers requirements for glazed openings in exterior walls and interior partitions.  Openings are discussed in detail in The Code Corner article Nos. 34 and 35, “Openings” Parts 1 and 2.  For this article, only the third area, life safety, will be discussed, which is covered in Chapter 24.  For glazing in elevator cars and hoistways, see The Code Corner No. 38, “Elevators.”

The terms glass and glazing have similar meanings and are frequently used interchangeably, but they do describe different things.  Glass is the material itself, whereas glazing, the noun, refers to any material used as an infill panel, whether it is glass, plastic, or some other material, which is installed in an opening.  Glazing, the verb, is defined by GANA as the “process of installing an infill material into a prepared opening in windows, door panels, partitions, etc.”

The life safety aspect of glass and glazing can be separated into two areas: structural loads and impact loads.  Although an impact load is a form of structural load, it is distinguished as a separate category due to its unique application requirements in the IBC.  There are two types of impact loads addressed by the IBC:  human impact loads and wind-borne debris impact loads.  In the IBC, structural loads are used to determine glass thickness.  For glazing sloped more than 15 degrees from vertical, the structural loads consist of wind, snow, seismic, and dead loads.  For vertical glazing of 15 degrees or less from vertical, the only structural loads considered are the wind and seismic loads.  Because the determination of glass thickness is a complex process, it should be accomplished by a registered structural engineer; therefore, this article will only address the basic concepts of glass structural design.

Glass is required to be provided with a manufacturer’s mark indicating glass type and thickness.  The marking may be omitted if approved by the building official and an affidavit from the glazing contractor is provided indicating that the glass conforms to the construction documents and the requirements of the IBC.  Tempered glass¹ must be permanently marked (e.g. acid or laser etched, sandblasted, ceramic fired, or embossed), except that tempered spandrel² glass, which may be provided with removable paper labels.

The IBC references ASTM E 1300, Standard Practice for Determining Load Resistance of Glass in Buildings.  This standard uses wind with a duration of 3 seconds as the basis of determining the maximum load resistance of glass.  Factors affecting load resistance of glass include the dimensions of the lite, the thickness of the glass, and the number of supported glass edges.  This load resistance must equal or exceed the calculated wind load determined per Section 1609 of the IBC.

Section 2403.2 states that if any edge of a glass pane is unsupported, or if the loads on the glass are unusual, then detailed drawings and analysis or test data are required.  A firmly supported edge is one where the framing member prevents the edge from deflecting more than 1/175 of the glass edge or ¾ inch, whichever is less.  As mentioned earlier, one of the factors affecting the load resistance of glass is the number of supported edges.  ASTM E 1300 provides load charts for glass supported on four sides to one side, which would contribute to the analysis.  Butt-glazed joints would be considered as unsupported edges.

While on the subject of butt-glazed units, Section 2403.4 addresses adjacent unsupported glass edges that are near an interior walking surface.  The provision requires that if a 50 plf load is applied to any point along one of the edges to a maximum height of 42 inches, the deflection cannot be greater than the thickness of the glass panel (See Figure 1).  This eliminates the possibility of someone leaning against one panel, causing it to deflect, and allowing someone to place fingers or other objects within the gap created.

Figure 1 - Deflection of interior butt-glazed panels.

Wind-Borne Debris Resistance

Impact loads created by wind-borne debris are only applicable to structures constructed within wind-borne debris regions.  Chapter 2 defines wind-borne debris regions as areas within 1 mile of a coastal high water line where the ultimate design wind speed is 130 mph or greater, areas where the ultimate design wind speed is 140 mph or greater, or Hawaii.  Design wind speeds are determined per Figures 1609A and 1609B, depending on the risk category of the structure per Table 1604.5.  Essentially, most glazing in structures along the Gulf and Atlantic coasts are subject to requirements for wind-borne debris impact.

To qualify for debris impact resistance, glazing must either be impact resistant or include a permanent impact-resistant covering that can protect the glazed opening.  The standards to test for impact resistance are ASTM E 1886, Test Method for Performance of Exterior Windows, Glazed Curtain Walls, Doors and Storm Shutters Impacted by Missiles and Exposed to Cyclic Pressure Differentials, and ASTM E 1996, Specification for Performance of Exterior Windows, Glazed Curtain Walls, Doors and Impact Protective Systems Impacted by Windborne Debris in Hurricanes.  If a glazed opening is within 30 feet of the grade, then the glazing must pass the large-missile test of ASTM E 1996.  If the glazed opening is greater than 30 feet above the grade, then the glazing need only pass the small-missile test of ASTM E 1996.  The IBC has some exceptions to these requirements, and also provides some substitutions that modify the application of ASTM E 1996.³

Human Impact Resistance

Glazing required to resist human impact needs to comply with the provisions of Section 2406, which requires testing in accordance with Consumer Product Safety Commission (CPSC) 16 Code of Federal Regulations (CFR) Part 1201, Safety Standard for Architectural Glazing Material.  Glazing not located in doors or in wet areas, such as hot tubs, bathtubs, showers, and saunas, may comply with ANSI Z97.1, Safety Glazing Materials Used in Buildings—Safety Performance Specifications and Methods of Test.  Both the Federal and ANSI standards use similar impact test stands (See Figure 2).

Figure 2 - Impact test stand per CPSC 16 CFR Part 1201.

The basic test involves raising the impactor—a punching bag filled with lead shot weighing 100 pounds.  To qualify as safety glazing, the test specimen must not, at a minimum, develop a hole in which a 4-pound 3-inch solid steel sphere could pass.  After the test, the specimen is rotated to the horizontal position and the sphere is placed in the opening.  If after one second the sphere has not dropped through, the specimen is deemed to have met the impact criteria.  Glass with a Category I rating (Class B per ANSI Z97.1) has passed the test when the impactor is raised 18 inches (measured vertically) above the impactor’s position at rest.  A Category II rating (Class A per ANSI Z97.1) is given to glass when the impactor is dropped from a height of 48 inches.

At a minimum, all safety glass must comply with the criteria for Category II; however, Category I glass is permitted when the exposed surface area of a single pane is 9 sq. ft. or less, except for glazing around wet areas per Section 2406.4.5.  Glazing is permitted to be tested by ANSI Z97.1, but must comply with Class A, unless otherwise indicated in Table 2406.2(2) to be Class B.  All safety glazing must be identified by a permanent marking that indicates the manufacturer and the safety standard with which it complies, plus the information previously mentioned.

The IBC identifies seven specific hazardous locations where safety glazing is required:

1. Glazing in Doors:  Section 2406.4.1 requires that all glass in swinging, sliding, and folding doors, whether the glass is operable or fixed, must be safety glass (See Figure 3).  Safety glazing is not required if the glazed opening does not permit the passage of a 3-inch-diameter sphere.  Additionally, decorative glass⁴, curved glass panels in revolving doors, and glass in commercial refrigerated cabinets are also exempt from the safety glazing requirement.
2. Glazing Adjacent to Doors:  Section 2406.4.2 requires all glazing, fixed or operable, that is within a 24-inch radius of the vertical edges of the door (hinge and latch edges) in a closed position with a bottom exposed edge of glass that is less than 60 inches above the walking surface be safety glazing (See Figure 3).  Exceptions include decorative glass, where an intervening wall or permanent barrier is between the door and glazing (See Figure 4), where access through the door is to a closet 3 feet or less in depth, or in walls on the latch side and perpendicular to the door in one- and two-family dwellings and R-2 dwelling units.
3. Glazing in Windows:  Section 2406.4.3 requires glazing in windows, whether fixed or operable, to be safety glass when all of the following conditions exist:

• The exposed area of glass in a single pane is greater than 9 sq. ft.
• The bottom edge of the glass is less than 18 inches above the floor.
• The top edge of the glass is greater than 36 inches above the floor.
• A walking surface is located within 36 inches of the glass measured perpendicular to the glass surface.

Figure 3 - Safety glazing in doors and adjacent to doors

Figure 4 - Exception to requirement for safety glass when partition is between door and adjacent glass.

One exception to the requirements is decorative glass.  Another exception is when a horizontal rail is installed across the glass at a height of 34 to 38 inches.  The horizontal rail must withstand a horizontal load of 50 plf without contacting the glass and must be a minimum of 1½ inches in height (See Figure 5).  The last exception applies to insulating glass installed 25 feet above a walking surface, roof, grade, or other surface with a slope within 45 degrees of horizontal.  With this exception, the outboard pane is not required to be safety glass.

Figure 5 - Glazing in windows adjacent to walking surfaces with Exception 2 shown.

1. Glazing in Guards and Railings:  Section 2406.4.4 requires safety glass when glass is used as structural balusters or as infill panels within a railing system of a different material.  The requirement is applicable regardless of height above a walking surface.  Section 2407 has specific provisions for glass in guards and railings, which require tempered glass or laminated glass fabricated with either tempered or heat-strengthened⁵ glass.  Glass balusters must have an attached handrail or guard, unless the baluster is constructed of laminated glass of equal type and thickness, can withstand the loads for handrails and guards per Section 1607.8, and is approved by the building official.  Handrails and guards are required to be supported by a minimum of three glass panels, unless they are designed to be supported by other means.
2. Glazing in Wet Areas:  Section 2406.4.5 requires safety glass (for single pane and all panes of multi-glazed units) installed as fences, enclosures, or walls near swimming pools, hot tubs, spas, whirlpools, saunas, steam rooms, bathtubs, and showers when the bottom edge of the glass is within 60 inches vertically above any standing or walking surface.  The exception to this is that safety glass is not required if the glass is located more than 60 inches from the edge of the water when measured horizontally from the face of the glass (See Figure 6).
3. Glazing Adjacent to Stairs and Ramps:  Section 2406.4.6 requires safety glass when the bottom edge of the glass is less than 60 inches above the plane of the walking surface of stairs, landings between flights of stairs, and ramps.  Safety glass is not required if the stairway, landing, or ramp has a guard between the walking surface and the glass, and the glass is more than 18 inches horizontally from the guard.  The guard must comply with Section 1013 and shall withstand the loads per Section 1607.8.  Another exception to the safety glass requirement is if the glass is 36 inches or more, measured horizontally, from the walking surface.
4. Glazing Adjacent to the Bottom Stair Landing:  Section 2406.4.7 requires safety glass at the bottom stair landing when the bottom edge of the glass is less than 36 inches above the landing and within 60 inches of the last tread measured horizontally.  The only exception is one similar to that for stairs and ramps, when the glass is protected by a guard complying with Sections 1013 and 1607.8 and the glass is more than 18 inches from the guard.

Figure 6 - Criteria for safety glazing adjacent to wet areas.

Sloped Glazing and Skylights

Skylights and sloped glazing, because of their typical condition of being installed over occupied spaces, are subject to special limitations to protect occupants from falling glass.  Glazing is considered sloped when the angle at which it is installed is more than 15 degrees from vertical.

The types of glass permitted in skylights and sloped glazing include laminated glass with a 30-mil interlayer (polyvinyl butyral or equivalent), wired glass, light-transmitting plastics per Section 2607, heat-strengthened glass, or fully tempered glass.  If the glazing system consists of multiple layers, then each layer can be of any allowed material.

If heat-strengthened and fully tempered glass is used monolithically (i.e. not part of a multi-glazed unit) or as the bottom layer of a multi-glazed unit, then screens must be installed within 4 inches directly below the glass to catch the fragments should the glass break.  Section 2405.3 provides specific criteria for the screening.  Screening is not required as permitted by several exceptions:

• Fully tempered glass is permitted without screening if the glass is located between intervening floors and is sloped 30 degrees or less from vertical.  Additionally, the highest point of the glazing must be 10 feet or less above the walking surface.
• Screening is not required for, and annealed glass is permitted in, glazing where the walking surface is permanently protected from falling glass, or the area below the glass is not a walking surface.
• Screening is not required for, and annealed glass is permitted in, sloped glazing of commercial or detached noncombustible greenhouses used only for growing plants and which is not open to the public.  The height of the greenhouse ridge is limited to 30 feet.
• Fully tempered glass is permitted without screen in Groups R-2, R-3, and R-4, provided no pane is larger than 16 sq. ft., the highest point is no more than 12 feet above a walking surface or other accessible area, and the glass is 3/16 inch or less in thickness.
• Laminated glass with 15-mil interlayer (polyvinyl butyral or equivalent) is permitted without screening if used within dwelling units in Groups R-2, R-3, and R-4, provided no pane is larger than 16 sq. ft. and the highest point is no more than 12 feet above a walking surface or other accessible area.

Framing of sloped glazing and skylights in Type I and II construction must be noncombustible.  The IBC does permit the use of pressure-treated wood or other materials, when approved by the building official, if the environment within the building has a corrosive effect on metal framing.  The framing system must be capable of supporting the design loads required by Chapter 16.  Skylights must be set on a 4-inch curb if the slope of the skylight unit is at an angle of 45 degrees or less from the horizontal.  A curb is not required for Group R-3 if the slope of the roof is a minimum of 14 degrees (3:12 slope).

Glazing in Athletic Facilities

 Due to the higher potential for impact against glass in athletic facilities, the IBC has established requirements specific to those uses.  In racquetball and squash courts, glass shall be tested per CPSC 16 CFR Part 1201 or ANSI Z97.1 at a drop height of 48 inches.  However, the test method is modified to test an actual installation or an identical assembly, with all the required fixtures and fittings, and the impact point is located at a height of 59 inches above the playing surface.  To pass the test, the glass must remain intact following the impact, and the deflection at the point of impact cannot exceed 1½ inches.  In gymnasiums and basketball courts, the glazing must comply with CPSC 16 CFR Part 1201, Category II, or ANSI Z97.1, Class A.

What Happened to Wired Glass?

Not mentioned directly in the IBC, but addressed via compliance with current safety glazing standards, is the absence of traditional wired glass as safety glass.  For decades, wired glass was exempt from the impact requirements of CPSC 16 CFR Part 1201 if used in areas where fire-resistance and safety glass was required.  With the introduction of specialty fire-resistive glass that can comply with safety glazing standards, the federal standard and the IBC have removed the exceptions, and traditional wired glass is no longer permitted in areas where safety glass is required.⁶  Contrary to popular belief, traditional wired glass is not gone—it has always been permitted where annealed glass is allowed and in fire windows where safety glazing is not required.  However, wired glass that does comply with safety glass standards is now available, which typically includes an added film to improve its performance.

The use of glass in building construction will continue to grow as the benefits of daylighting are realized and integrated into building design.  Further, glass technology continues to improve allowing greater expanses of glazing with greater energy efficiency.  Glass is also being used in more creative applications, generating specialized areas in structural glazing systems.  Not addressed by the building code, but applicable based on circumstances, is the availability of security glass.  Although safety glass minimizes potential injury from accidental impact, it is not intended to prevent unwanted entry, stop the passage of a projectile fired from a weapon, or withstand the pressures created by an explosion.  Glass used in these applications is subject to additional testing based on standards that require a minimum performance that far exceeds those for safety glass.  Regardless of the varieties of glass types and performance levels that are available in the construction market, the basic requirement for safety still applies.

---

¹   Tempered glass is defined by GANA as “Flat or bent glass that has been heat-treated to a high surface and/or edge compression to meet the requirements of ASTM C 1048, Kind FT.”  “FT” means “fully tempered.”

²   Spandrel is defined by GANA as “panel(s) of a wall located between vision areas of windows, which conceal structural columns, floors and shear walls.”

³   For more information about wind-borne debris-resistant design, see “Glazing Design Beyond the Minimum” in the May 2012 issue of The Construction Specifier.

⁴   Decorative glass is defined in the IBC as a “carved, leaded or Dalle glass or glazing material whose purpose is decorative or artistic, not functional; whose coloring, texture or other design qualities or components cannot be removed without destroying the glazing material and whose surface, or assembly into which it is incorporated, is divided into segments.”  Dalle glass is made up of glass pieces “embedded in a cast matrix of concrete or epoxy.”

⁵   Heat-strengthened glass (Kind HS, per ASTM C 1048) is heat-treated glass similar to fully tempered, but at a compressive strength that is much lower than fully tempered.  Heat-strengthened glass is about two times stronger than annealed glass, but is not considered safety glass per CPSC 16 CFR Part 1201 or ANSI Z97.1.  Annealed glass is float glass that has been through a controlled cooling process.

⁶   See The Code Corner No. 5, “How You Can Change a Building Code,” for more information on the elimination of the wired glass exemption.

Elevators

One hundred and sixty years ago, Elisha Otis invented the first braking mechanism for the elevator, which made vertical travel within a building feasible and safe.  A little over forty years later, the gearless traction elevator was developed, which allowed movement in buildings of significant height.  Thus, along with the advent of inexpensive materials and advanced engineering and construction methods, the automatic elevator became a pivotal step that led to the surge of high-rise construction in the United States.  Since its introduction, the elevator has seen numerous advancements, but its purpose remains the same: moving people between floors of multi-story buildings efficiently and safely.

Like other systems within a building, elevators are regulated by the building code.  In the International Building Code (IBC)¹, Chapter 30 establishes the primary criteria for elevators, while other sections of the IBC supplement the primary criteria with special provisions, such as requirements for accessible means of egress, elevator lobbies, and shaft enclosures for hoistways.  In addition to the provisions in the IBC, elevators must also comply with the requirements in the American Society of Mechanical Engineers’ (ASME) A17.1, Safety Code for Elevators and Escalators², and ICC/ANSI A117.1, Accessible and Usable Buildings and Facilities³, which are referenced by the IBC.

General Elevator Planning and Design

With a couple of exceptions, neither the IBC nor ASME A17.1 dictate the number of elevators that must be provided in a building—any number of elevators may be provided at the discretion of the building owner.   The owner or architect may hire an elevator consultant to determine the elevator needs for buildings with high traffic or complex usage requirements.

As stated, there are a couple of exceptions in which the code regulates the number of elevator cars.  The first exception is in Section 1007.2.1, which requires at least one elevator be provided as one of the required accessible means of egress if an accessible story is located four or more stories above or below the level of exit discharge.  However, the elevator is not required if the building is sprinklered throughout per Section 903.3.1.1 (NFPA 13) or Section 903.3.1.2 (NFPA 13R), and includes either a ramp from the stories, or the stories incorporate a horizontal exit at or above the level of exit discharge.  The second exception is in Section 403.6, which requires at least two elevators be designated as fire service access elevators in buildings with occupied floors greater than 120 feet above the lowest level of fire department vehicle access.

If multiple elevators are provided in a building, the IBC requires that the number of cars within a single hoistway enclosure be limited to no more than four.  However, if four or more elevator cars serve all or the same stories, then the elevators must be located in a minimum of two hoistway enclosures.  Thus, if four elevator cars are provided, then they must be located in two hoistways in a 2-2 or 1-3 combination (See A and B in Figure 1).  If six elevator cars and two hoistways are provided, then the only combinations permitted would be 3-3 or 2-4 (See C and D in Figure 1)—a 1-5 combination would not be permitted, since no more than four cars are allowed in a single hoistway.

Figure 1 - Number of elevator cars in a hoistway.

Elevator car size is also regulated by the IBC and by ICC/ANSI A117.1.  In the IBC, if an elevator is provided in a building that has four or more stories above or below the grade plane, then at least one elevator shall be sized to accommodate an ambulance stretcher that is 24 inches wide by 84 inches long with corners having radii of 5 inches or more.  In ICC/ANSI A117.1, elevator cars shall have a clear dimension of 60 inches wide and 60 inches deep or 54 inches wide and 80 inches deep.  Elevator cars with centered doors may be 51 inches deep (54 inches to the doors) and 80 inches wide, provided the door has a 42-inch minimum width.  Additionally, elevator cars with 36-inch-wide side doors may be equally deep, but need only be 68 inches wide.  Existing elevators are exempt from the previous size criteria, provided elevators cars have clear dimensions of 36 inches wide and 54 inches deep, and have a clear floor area of 16 sq. ft.

Elevator hoistways penetrating more than three stories are required to provide venting at the top of the hoistways to allow heat and smoke to escape.  Except for Groups R-1, R-2, I-1, I-2, and other occupancies with sleeping units, venting is not required when the building is sprinklered throughout in accordance with NFPA 13 or 13R.  When venting is required, the vents must open directly to the exterior or through noncombustible ducts that terminate at the exterior.  The area of the vents shall be 3½% of the hoistway, but not less than 3 sq. ft. per elevator car.  Of the total required venting area, not less than ⅓ of the area must be permanently open with the remaining area closed off with annealed glass not greater than ⅛ inch thick.  Permanently opened venting is not required if automatic vents are installed that open when smoke is detected in the hoistway or in the elevator lobby (if lobbies are provided), upon power failure, or when activated by manual control. 

Other considerations that go into planning and design for elevators—also affected by the codes—are machine rooms, elevator lobbies, pits and clearances, and car finishes.  Machine rooms are regulated by both the IBC and ASME A17.1.  Requirements for elevator lobbies are only located in the IBC, while pits and clearances are only regulated by ASME A17.1.  Regarding elevator car finishes, the IBC is not very specific, but will likely consider elevators as enclosed spaces per Table 803.9.  On the other hand, ASME A17.1 provides specific criteria for car finishes and may supersede IBC criteria.

Pits and Clearances

ASME A17.1 separates criteria for pits and clearances in hoistways between electric and hydraulic elevators in Parts 2 and 3, respectively.  Typically, most of the requirements are in Part 2 and referenced by Part 3, except where specifically modified for hydraulic elevators.  For both types of elevators, the pit depth is based on the required equipment plus the minimum bottom car clearance of 24 inches when the elevator rests on fully compressed buffers or bumpers.  For top clearances, the requirements are basically the same, except the dimensions will likely vary between electric elevators (either counterweighted or uncounterweighted⁴) and hydraulic elevators.  Therefore, for design purposes, consult manufacturers’ design criteria for the types of elevators under consideration.

Machine Rooms

ASME A17.1 provides the majority of the technical requirements for machine rooms and spaces, but defers fire-resistive requirements to the building code.  The minimum clear headroom in a machine room per ASME A17.1 is 84 inches.  If fire resistance of the machine is not required by the building code, ASME A17.1 requires that machine rooms be constructed of noncombustible materials to a minimum height of 79 inches.  The IBC requires that machine rooms be of fire-resistive construction complying with the requirements for fire barriers, horizontal assemblies, or both.  The rating must be equal to the rating of the hoistway.  IBC Section 3002.1 requires that hoistways comply with Section 713 for shaft enclosures; therefore, if the shaft connects four or more stories, then the hoistway and the machine room must have a fire-resistance rating of 2 hours, or 1 hour if connecting fewer than four stories.  However, two exceptions are provided in the IBC:

• If a fire-resistance rating of 2 hours is required, then only a 1-hour rating is required if the machine room is not directly adjacent to the hoistway and no openings are provided between the hoistway and machine room.
• If the building is four stories or less and the machine room is not directly adjacent to the hoistway and no openings are provided between the hoistway and machine room, then the machine room is not required to have a fire-resistance rating.

The IBC simply states that machine rooms are to have an approved means of access; thus, the detailed criteria in ASME A17.1 will establish the minimum requirements for the means of access.  If the machine room is elevated above the floor or roof surface, then a permanent and noncombustible set of stairs or ladder, along with a landing at the top, is required to reach the machine room door.  The landing must be sized to allow the full swing of the door plus 24 inches if the door swings outward, or 29.5 inches if the door swings inward.  Although ASME A17.1 allows doors to machine rooms to have a width of 29.5 inches, the IBC requires a minimum clear width of 32 inches. 

If access to the machine room is across a roof, a stairway with a swing door shall be provided to the roof from the floor below—roof access hatches are not permitted.  If the roof slopes more than 15 degrees or the roof does not have a minimum 42-inch-high parapet or guardrail around the roof or passageway to the machine room, then a walkway must be provided.  The walkway must be 24 inches wide with railings 42 inches high consisting of a top rail, an intermediate rail or solid panel, and 4-inch-high toe-boards.

Elevator Lobbies

Elevator lobbies are required on each floor where an elevator shaft enclosure (i.e. hoistway) connects three or more stories.  The exceptions to the code do not require lobbies under the following conditions or locations:

• On the level of exit discharge if the level is sprinklered in accordance with NFPA 13.
• Elevators not required to be enclosed in a shaft per IBC Section 712.1.
• When hoistway openings are provided with additional doors that comply with smoke and draft control requirements of IBC Section 716.5.3.1 and tested per UL 1784, Air Leakage Tests of Door Assemblies, without a bottom seal.
• When the building is sprinklered throughout in accordance with NFPA 13 or 13R.  However, this exception is not permitted in Groups I-2 and I-3 and in high-rise buildings⁵.
• Elevator hoistways pressurized in accordance with IBC Section 909.21.
• Elevators only serving open parking garages.

When required or provided, elevator lobbies shall be enclosed with walls complying with the requirements for fire partitions.  Since elevator lobbies must have at least one means of egress, doors in elevator lobby enclosure walls shall comply with requirements for doors in corridors.  Ducts and air transfer openings in elevator lobby enclosures shall also be protected as required for corridors.  Elevator lobby enclosures may be constructed as smoke partitions per Section 710 in lieu of fire partitions, provided the building is sprinklered throughout in accordance with NFPA 13 or 13R.  If smoke partitions are provided, then doors need to comply with requirements for smoke and draft control.

Elevator lobbies are also required in the following special conditions and must comply with the requirements unique to each condition:

• Underground buildings where the elevator or elevators are shared by both smoke compartments⁶.
• Elevators designated as fire service access elevators.
• Elevators designated as occupant evacuation elevators.
• Elevator lobbies serving as areas of refuge.

Elevator Finishes and Materials

The IBC states that interior finishes for enclosed spaces must be of Class C or B materials, depending on whether the space is sprinklered or not.  However, that is not a decision that needs to be determined since ASME A17.1 requires finishes to be of Class B materials (a flame spread index less than or equal to 75 and a smoke developed index less than or equal to 450) when tested in accordance with ASTM E 84, Test Methods for Surface Burning Characteristics of Building Materials, or UL 723, Standard for Test for Surface Burning Characteristics of Building Materials.

If carpet or fabric (napped, tufted, woven, or looped) is used on elevator car walls, the material must be tested using the method specified in Section 8.3.7 of ASME A17.1.  The material shall not have a burn length greater than 8 inches, the flame shall extinguish within 15 seconds after removal of the flame source, and drippings shall not burn for more than 5 seconds.  Floor coverings, underlayments, and adhesives must have a critical radiant flux of not less than 0.45 W/cm² when tested in accordance with ASTM E 648, Standard Test Method for Critical Radiant Flux of Floor-Covering Systems Using a Radiant Heat Energy Source.  Handrails are permitted, but not required, inside elevator cars.

Glazing is permitted in elevator cars and hoistways per IBC Section 2409 and ASME A17.1.  When installed in elevator hoistways, glass shall be laminated safety glazing complying with 16 CFR 1201 Category II or ANSI Z97.1 Class A.  If the hoistway is required to be fire-resistance rated, then the glazing must also comply with IBC Section 716 for opening protectives.  Since Section 716 is referenced, glazing tested in accordance with ASTM E 119, Test Methods for Fire Tests of Building Construction and Materials, or UL 263, Standard for Fire Tests of Building Construction and Materials, may be used in lieu of complying with the limitations of Section 716. 

In hoistway doors, glass shall comply with the same criteria for hoistways, except that ASME A17.1 permits wire glass in vision panels without reference to any safety glazing standards; however, the IBC will permit wire glass provided that the glass complies with the safety glazing standards previously mentioned.  With the exception of vision panels, glazing in hoistway doors must not be less than 60% of the total visible door surface area; likewise, car doors must have the same minimum area for glass as viewed from the car side.  There is no requirement that glass, if provided, must be used in both the car and hoistway doors, nor is it required that the areas of glazing in each be equal.

When glass is installed as part of the elevator car enclosure, ASME A17.1 requires laminated safety glazing complying with 16 CFR 1201 and that it be mounted so that the assembly will pass the elevator tests without damage.  Additionally, ASME A17.1 requires that a handrail or other framing be provided if the glass panels are wider than 12 inches.  The IBC further requires that glass used within an elevator, either as a wall lining or as part of the enclosure, comply with 16 CFR 1201 Category II or ANSI Z97.1 Class A.  Since ANSI Z97.1 is not referenced by ASME A17.1, then, to comply with both codes, only materials complying with 16 CFR 1201 Category II should be used. 

Both the IBC and ASME A17.1 allow tempered glass when used as a lining for elevator car walls.  If used, tempered glass must be bonded to a coating, sheeting, or film backing to hold fragments in place if broken.  The tempered glass cannot be sandblasted, etched, heat treated, painted, or have received any other treatment that would affect the characteristics of the glass.  Finally, the IBC requires that tempered glass comply with 16 CFR 1201 Category II or ANSI Z97.1 Class A, which is more specific than the safety glazing requirements specified by ASME A17.1.

Elevators as Accessible Means of Egress

Elevators required or provided as an accessible means of egress must comply with requirements in IBC Section 1007.4.  To be considered an accessible means of egress, elevators must be provided with standby power in accordance with NFPA 110, Emergency and Standby Power Systems, or NFPA 111, Stored Electrical Energy Emergency and Standby Power Systems.  NFPA 110 provides requirements for generators, whereas NFPA 111 provides requirements for stored energy type systems, such as batteries.

As previously mentioned, elevator lobbies may serve as a required area of refuge for elevators used as an accessible means of egress.  Elevators are not required to be accessed by an area of refuge when buildings are sprinklered throughout with a system complying with NFPA 13 or 13R, when elevators are not required to be enclosed in a shaft, and when elevators are accessed by a horizontal exit.  If used as an area of refuge, elevator lobbies must be enclosed with smoke barriers and provided with two-way communication to the fire command center or other location approved by the fire department.  Also, elevator lobbies used as areas of refuge must accommodate one 30- by 48-inch wheelchair space for every 200 occupants served by the area of refuge.  The wheelchair spaces cannot reduce the required means of egress width.

Fire Service Access and Occupant Evacuation Elevators

Fire service access and occupant evacuation elevators were introduced in the 2009 IBC and modified in the 2012 IBC.  As mentioned earlier, buildings with an occupied floor more than 120 feet above the lowest level of fire department vehicle access must provide two elevators designated as fire service access elevators.  Passenger elevators in high-rises are permitted to be used as occupant evacuation elevators.  Additionally, in high-rise buildings greater than 420 feet in height, elevators complying with the requirements for occupant evacuation may be used in lieu of the required third stairway.

Fire service access elevators were added to the IBC in Section 3007 as a result of research conducted following the World Trade Center tragedy of September 11, 2001.  According to the code change proposal, these requirements were recommended to “provide a reasonable degree of safety for firefighters” when “staging firefighters and equipment one or two floors below the fire.”  Elevators used for fire service access are required to be identified by a pictorial symbol representing a firefighter’s helmet that shall be mounted on the face of hoistway door frame that is perpendicular to the hoistway door.

Fire service access elevators must have access to a fire service access elevator lobby on each floor, except at the level of exit discharge.  Each lobby shall have direct access to an interior exit stairway, which shall be provided with a Class I standpipe.  If a fire service access elevator has two entrances to a floor, the second entrance is permitted to have access to a standard elevator lobby as described earlier.  Fire service access elevator lobbies must be enclosed with smoke barriers.  Doorways to a fire service access lobby shall be fire door assemblies having a ¾-hour rating and complying with smoke and draft control requirements of Section 716.5.3.1.  The size of a fire service access elevator lobby must be a minimum 150 sq. ft. in floor area with no dimension less than 8 feet.

Other unique criteria apply to fire service access elevators.  For example, sprinklers are not permitted in machine rooms, machine spaces, and hoistways of fire service access elevators, and water from sprinklers outside the fire service access elevator shall be prevented by approved means from entering the fire service access elevator hoistway.  Fire service access elevators and associated equipment shall be supplied by normal and standby power.  Wires and cables from outside the fire service access elevator that provide power, communications, fire detection, and control signals for the elevator must be protected by construction having a fire-resistance rating of not less than 2 hours.

Occupant evacuation elevators were added to the IBC in Section 3008 to provide occupant self-evacuation.  Prior to the introduction of occupant evacuation elevators in the 2009 IBC, elevators were not permitted to be used by building occupants for means of egress.  These provisions are voluntary, but, if provided, all public passenger elevators must comply with the provisions.  For the most part, occupant evacuation elevators must comply with the same requirements for fire service access elevators in regard to the fire sprinkler prohibition, prevention of outside sprinkler water from entering the hoistway, and protection of wires and cables. 

Elevator lobbies serving occupant evacuation elevator have requirements identical to fire service access elevator lobbies, such as smoke barrier enclosure construction (except at level of exit discharge), doorways, and access to an interior exit stairway; however, occupant evacuation elevator lobbies have additional provisions.  Doors, in addition to the fire-resistive requirements, must also have vision panels consisting of fire-protection-rated glazing and be automatic closing by fire alarm signal if kept open by magnetic or other hold-open devices.  The size of the occupant evacuation elevator lobby shall be a minimum of 3 sq. ft. per occupant based on not less than 25% of the floor occupant load served by the lobby.  Furthermore, a 30- by 48-inch wheelchair space is required for every 50 occupants of the occupant load of the floor area served by the lobby.  The lobby shall also be provided with two-way communication identical to that required for areas of refuge.

Occupant evacuation elevators shall be identified as such on all floors with an approved sign located adjacent to each call station.  Lobbies serving occupant evacuation elevators must provide a status indicator that shows by green illumination that elevators are available for occupant evacuation when elevators are in normal service and the fire alarm system has indicated an alarm.  If the elevators have been switched to emergency recall service by the fire department, the status indicator should show by red illumination that elevators are not available for evacuation and that stairs should be used.  At all other times, no illumination or message should be indicated.

Structural Integrity for High-Rise Elevator Hoistways

If high-rise buildings are classified as Risk Category III or IV⁷ in accordance with Section 1604.5, or if the building has a height greater than 420 feet, then elevator hoistway enclosures must comply with the requirements for structural integrity per Section 403.2.3.  These provisions were introduced in the 2009 IBC as a result of recommendations developed following the World Trade Center tragedy.  The intent is to provide increased resistance to structural damage from external impacts.

The wall assembly surrounding a hoistway must comply with Soft Body Impact Classification Level 2 as determined by ASTM C 1629/C 1629M, Standard Classification for Abuse-Resistant Nondecorated Interior Gypsum Panel Products and Fiber-Reinforced Cement Panels, which requires the entire assembly to withstand an impact of a 195 pound force.  The exterior face of the hoistway (the wall surface not facing the stairway) must consist of either two layers of material complying with Hard Body Impact Classification Level 2, or one layer of material complying with Hard Body Impact Classification Level 3.  Additionally, any materials that, when combined and tested together, comply with Hard Body Impact Level 3 shall be permitted.  Concrete and masonry construction are deemed to comply with the requirements for the Soft Body and Hard Body Classification requirements and are not required to be tested.

------------------

This article does not attempt to address all the requirements relating to elevators.  Most of the requirements associated with elevators—essentially those in ASME A17.1—pertain to the fabrication of elevators and associated equipment and accessories, of which elevator manufacturers are acutely aware.  Specifications for elevators in the construction documents should require compliance with ASME A17.1 and with ICC/ANSI A117.1, the 2010 ADA Standards, or both.  Since elevators vary among manufacturers, design professionals should consult manufacturer representatives when designing and specifying elevators, especially if custom designs are proposed for elevator cars, entrances, call stations, and hall signals.

---

¹   References to the IBC are for the 2012 edition unless indicated otherwise.

²   The 2007 edition of ASME A17.1 is referenced by the 2012 IBC.

³   The 2009 edition of ICC/ANSI A117.1 is referenced by the 2012 IBC.  The elevator requirements in the 2009 ICC/ANSI A117.1 is virtually identical to the 2010 ADA Standards, which were adopted by the Department of Justice to replace the ADA Accessibility Guidelines (ADAAG).

⁴   Counterweighted elevators use ropes with weights to help offset the weight of the elevator car for ease in moving the car.  Uncounterweighted elevators are identified by ASME A17.1 as screw column elevators and rack-and-pinion elevators that do not require counterweights.

⁵     High-rise buildings are defined as buildings with an occupied floor located more than 75 feet above the lowest level of fire department vehicle access.

⁶     Underground buildings as buildings with an occupied floor more than 30 feet below the lowest level of exit discharge.  Requirements for underground buildings are located in Section 405 of the IBC.  Underground buildings with floors more than 60 feet below the level of exit discharge must be divided into two smoke compartments, each with access to an elevator unless the elevator or elevators are shared by both compartments.

⁷     Risk Category III buildings are those “that represent a substantial hazard to human life in the event of failure,” and Risk Category IV buildings are those “designated as essential facilities.”  Refer to Table 1604.5 for specific uses identified for each category.

Fire Walls

Passive fre protection has been a significant component of building codes since the publication of the first Building Code recommended by the National Board of Fire Underwriters (NBFU) in 1905—even Nero established some form of passive fire protection in Rome after it burned in 64 A.D.  Passive fire protection is the use of building materials to limit the effects of fire on a building or to contain the spread of fire within a building or between separate buildings.  In the 1905 edition of the NBFU Building Code, passive fire protection, which came in the form of “Fireproof Buildings,” was determined through prescriptive requirements based solely on the use of materials such as brick, stone, concrete, iron, and steel, without consideration of how well the materials performed under actual fire conditions.

However, over the past 100 years, building codes have continually been improved to reflect new technologies and unfortunately, to respond to tragic events such as the attacks on the World Trade Center on September 11, 2001.  Additionally, testing standards have also developed over time and have become an integral part of building code compliance.  For example, in 1918 the American Society for Testing and Materials, or ASTM (now only called ASTM International) published its first standard for the fire testing of materials as standard C19, which is now known as ASTM E 119, Standard Test Methods for Fire Tests of Building Construction and Materials.  For many years, ASTM E 119 has been the basis for determining the fire resistance of building construction in model building codes, but in the 2009 International Building Code (IBC), Underwriters Laboratories (UL) 263, Fire Tests of Building Construction and Materials, was added as an alternative.

In the IBC, fire-resistive construction is used to satisfy requirements for type of construction or for assemblies such as fire barriers, fire partitions, smoke barriers, horizontal assemblies, and fire walls.  The last of that list—fire walls—can serve two purposes.  Unlike other fire-resistive assemblies, a fire wall is used to divide a large, single building on the same lot into two or more buildings, or to serve as a shared wall between two buildings on different lots. 

Dividing a Building on the Same Lot – This application of a fire wall can achieve one or both of the following objectives:

1. To divide a large building into smaller “buildings” in order to permit the application of a less restrictive construction type that has a lower allowable area.  For example, if a Group B, Type VA building is permitted 18,000 sq. ft. in floor area (without sprinklers), a fire wall can divide the building in half to create two 9,000 sq. ft. “buildings” of Type VB construction.
2. To separate a building into two or more “buildings” so that different construction types may be used.  This is commonly used for additions to existing buildings when it is desired to have an addition that does not conform to the requirements of the existing building’s construction type.  For example, if the design team wants to add a Type VB combustible addition to an existing building of Type IIB noncombustible construction, a fire wall is required between the two types of construction.

Separating Buildings on Different Lots – A fire wall used for this purpose is called a “party wall” and is situated on the lot line and is shared by each building on each lot.  Per Section 706.1.1 of the IBC¹, fire walls used as party walls are not permitted to have openings.

Materials and Fire-Resistance Ratings

Fire wall materials are limited to noncombustible materials such as masonry, concrete, and metal studs with gypsum board.  Combustible construction, such as wood studs, is only permitted in Type V construction.

The fire-resistance rating of a fire wall depends on the occupancy group or groups divided by the fire wall, and to a lesser extent, the construction type.  The minimum fire-resistance rating is 2 hours, but fire walls can have ratings of 3 and 4 hours.  Table 706.4 provides the required ratings for fire walls and, per the footnotes, allows some exceptions.  For example, a Group B building is required to have a 3-hour fire wall; however if the building is of Type II or V construction, the rating can be reduced to 2 hours. 

If the fire wall separates buildings of differing occupancy groups, the most restrictive rating shall be used.  Where a fire wall also serves as a required separation between occupancy groups or fire areas, the most restrictive fire-resistance rating of either the fire wall or the fire barrier separating wall shall be applied.  The same restriction also applies to differing construction types.  If the fire wall separates two buildings of different construction type, the most restrictive application shall be used.  For example, if a Group B building is divided by a fire wall and one building is of Type I construction and the other is of Type II construction, a 3-hour fire wall is required, even though the Type II construction is permitted a reduction to 2 hours.

Fire Wall Design

Although the role of a fire wall in a building’s passive fire protection system may sound simple in concept, it is the understanding of fire wall design that seems to be elusive to many design professionals.  One of the more confusing design features of a fire wall is the requirement for structural stability—the fire wall must remain in place if the building on either side of the fire wall collapses.  To maintain the required structural stability, fire walls are often independent of a building’s structural system, thus allowing the structural frame of a building to fail and not bring down the fire wall along with it.

For floors and roofs that are framed using combustible wood members, such as glue-laminated or heavy timber construction, the structural members can bear on a fire wall without compromising the fire wall’s structural stability and fire-resistive performance.  These structural members, when embedded in the fire wall, must have what is known as a “fire cut” to allow the member to fall out of the embedment without damaging the structural integrity of the fire wall.  However, when these combustible structural members are embedded in the fire wall, per Section 706.7 there must be a minimum of 4 inches between the ends of the structural members.  If the wall is hollow, such as with concrete masonry units, then the hollow spaces must be filled solidly for the full thickness of the cavity for a distance of 4 inches above, below, and in between the structural members.

Horizontal Continuity

Since a fire wall is required to extend from exterior wall to exterior wall (Section 706.5), the termination of a fire wall at the exterior wall can be a little confusing.  The basic requirement in the IBC states that a fire wall must extend 18 inches beyond the exterior surface of the exterior wall.  However, three exceptions are offered that eliminate the wall extension:

1. The fire wall may terminate at the interior surface of exterior combustible sheathing or siding, provided the exterior wall has a 1-hour fire-resistance rating that extends 4 feet on each side of the fire wall and any openings within this protected area have a fire protection rating of 45 minutes.
2. The fire wall may terminate at the interior surface of noncombustible sheathing, siding, or other material, provided the noncombustible material extends at least 4 feet on each side of the fire wall.
3. The fire wall may terminate at the interior surface of noncombustible sheathing where the building on each side of the fire wall is sprinklered in accordance with the National Fire Protection Association’s (NFPA) 13, Installation of Fire Sprinkler Systems, or NFPA 13R, Installation of Fire Sprinkler Systems in Residential Occupancies Up to and Including Four Stories in Height, with IBC exceptions.

The requirement and exceptions described above are applicable to fire walls that terminate at exterior walls that are 180 degrees or more from each other.  However, when fire walls intersect exterior walls that are less than 180 degrees apart, other requirements come into play.  Per Section 706.5.1, there are two options available for working with this type of exterior wall condition.  Option 1 is a simple method that requires the exterior walls within 4 feet on each side of a fire wall to be constructed of 1-hour fire-resistive construction and any openings within this protected area must have a minimum 45-minute fire protection rating (See Figure 1).  Option 2 is a little more complex and involves the application of an imaginary lot line that extends from the termination of the fire wall to a point beyond the building or to an actual lot line so as to determine exterior wall and opening protection per Sections 705.5 and 704.8, respectively (See Figures 2 and 3).

 Figure 1 –Termination of fire wall at exterior walls less than 180° apart using Option 1 simple prescriptive method


Figure 2 – Example of terminating fire wall at exterior walls less than 180° apart using Option 2 fire separation distance method.

Figure 3 – Another Option 2 example using a different imaginary lot line location.

Building elements that project horizontally from the face of an exterior wall, such as balconies, roof overhangs, and canopies, provide opportunities for fire to circumvent fire wall construction.  Therefore, the IBC requires that fire walls extend to the outer edge of projecting elements when they are within a distance of 4 feet of the fire wall (See Figure 4).  Typical of most code requirements, there are exceptions:

Figure 4 – Requirement for fire wall through projecting element.

1. If the projecting element does not include concealed spaces, the fire wall need only comply with the basic requirements for fire wall horizontal continuity when the wall behind and below the projecting element is constructed of 1-hour fire-resistive construction for a distance equal to the depth of the projecting element on each side of the fire wall.  Openings within the protected exterior wall area must have a minimum fire protection rating of 45 minutes (See Figure 5).
2. If the projecting element is noncombustible and does include concealed spaces, then the installation of a 1-hour fire-resistive wall through the concealed space that aligns with the fire wall is required.  The construction of the projecting element must be of 1-hour fire-resistive construction for a distance equal to the depth of the projecting element on each side of the fire wall (See Figure 6).  The separation wall below the projecting element may be omitted provided the exterior wall below the projecting element is of 1-hour fire-resistive construction for a distance equal to the depth of the projecting element on each side of the fire wall (See Figure 7).  Openings within the protected exterior wall area must have a minimum fire protection rating of 45 minutes.
3. If the projecting element is combustible and does include concealed spaces, then the fire wall is only required to extend through the projecting element to the outer edge.  The construction of the exterior wall below and behind the projecting element must be of 1-hour fire-resistive construction for a distance equal to the depth of the projecting element on each side of the fire wall.  Openings within the protected exterior wall area must have a minimum fire protection rating of 45 minutes (See Figure 8).

Figure 5 – Requirement for fire wall through projecting elements without concealed space.

Figure 6 – Requirement for fire wall through noncombustible projecting element with concealed space.

Figure 7 – Alternate requirement for fire wall through noncombustible projecting element with concealed space.

Figure 8 – Requirement for fire wall through combustible projecting element with concealed space

Vertical Continuity

In addition to the horizontal extension of fire walls to the exterior walls, fire walls are also required to extend from the foundation to a point that is 30 inches above the adjacent roof surfaces (See Figure 9).  As with exterior walls, the vertical extension of a fire wall also has exceptions:

Figure 9 – Vertical extension of fire wall through roof.

1. Fire walls in stepped buildings must extend 30 inches above the lower roof surface, and for 15 feet above the lower roof, the exterior wall must be protected with 1-hour fire-resistive construction and any openings in the protected area must have a minimum fire protection rating of at least 45 minutes (See Figure 10).
2. 2-hour fire walls may terminate at the underside of roof sheathing, decks, or slabs, provided the lower roof assembly is constructed of 1-hour fire-resistive construction within 4 feet of the fire wall and the supporting elements for the roof assembly are protected for the full length with an equal fire-resistive rating.  Also, no openings are permitted within the 4-foot protected area and the roof must have a Class B roof covering (See Figure 11).
3. Fire walls may terminate at the underside of noncombustible roof sheathing, decks, or slabs, provided the building on each side has a Class B roof covering and no openings are located within 4 feet of the fire wall (See Figure 12).
4. Fire walls in buildings of Type III, IV, and V construction may terminate at the underside of combustible roof sheathing or decks provided the sheathing or deck is constructed of fire-retardant-treated wood extending at least 4 feet on each side of the fire wall or the sheathing or deck is protected by 5/8-inch-thick Type X gypsum board applied directly to the underside of the sheathing or deck for a distance of 4 feet on each side and supported by 2-inch nominal ledgers.  Also, no openings are permitted within 4 feet of the fire wall and the roof must be covered by a Class B roof covering (See Figure 13).
5. Buildings permitted to be separated by a 3-hour horizontal assembly per Section 509.2 (commonly referred to as “podium” construction), may have the fire wall terminate at the horizontal separation and need not extend to the foundation.

 Figure 10 – Fire wall extension through roof for stepped buildings

Figure 11 – 2-hour fire wall termination at underside of roof

Figure 12 – Fire wall termination at noncombustible roofs

Figure 13 – Fire wall termination at combustible roofs for Type III, IV, and V construction.  Left side shows fire-retardant-treated wood option and right side shows gypsum board application method

Openings and Joints

Openings are permitted in fire walls and are discussed in detail in The Code Corner No. 34 “Openings – Part 1.”  Joints within fire walls and between fire walls and other fire-resistive construction, such as floor or floor-ceiling assemblies and roof or roof-ceiling assemblies, must be protected for a time period that is not less than the required rating of the fire wall, roof, or floor.

Fire Wall Alternatives

Fire walls are frequently considered as single wall assemblies, but a single wall is only one method of achieving the required structural and fire-resistive performance.  Double-wall assemblies can be provided as an alternative using the prescriptive requirements in the IBC.  These methods provide a cost-effective solution when a fire wall is needed between an existing building and a new addition. 

If a building on the same lot is divided by a fire wall and no openings are planned within the fire wall, a double-wall option can be utilized using the requirements for exterior wall construction where each wall is considered to be adjacent to an imaginary lot line.  For example, assume a Type V, Group B building is divided by a double-wall fire wall along an imaginary lot line.  Since the fire separation distance is less than 5 feet, the fire-resistive rating is required to be 1-hour per Table 602.  Therefore, each wall must have a 1-hour rating.  If a single fire wall were used, the rating would have to be 2-hours.  However, although a single-wall fire wall is allowed openings, when using the double-wall option as exterior walls, the individual walls are not permitted openings per Table 705.8, since the fire separation distance is less than 3 feet per.

If a fire wall with openings is required, then the double-wall method is still an option; however, the design of the openings becomes a challenge.  As stated earlier, the structural stability of the fire wall is paramount and the double-wall fire wall allows each wall within the assembly to support the floors and roof of its respective “building,” allowing either building to collapse along with its side of the fire wall, leaving the other wall intact.  But openings through these double-wall assemblies must also remain in place if either wall collapses, and herein lies the complexity of double-wall fire walls.

Unless double doors are used, such as that between adjoining rooms in a hotel (which would not allow them to be used as means of egress doors), then openings through a double-wall fire wall must be designed as structurally independent elements and cannot be anchored to either wall of the double-wall assembly. Therefore, frames of openings must have their own foundation systems that will keep them erect if either wall collapses.

Unlike the exterior wall method, the fire-resistance rating for each wall in a double-wall fire wall will require the same rating as that for a single-wall fire wall.  However, an alternative method is available that can be proposed to the building official using Section 104.11, “Alternative materials, design and methods of construction and equipment,” if using the 2009 or earlier editions of the IBC (the 2012 IBC includes this alternative).  The alternate method employs the use of NFPA 221, Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls.  This standard essentially provides the same method described above for double-wall fire walls with openings, but the NFPA standard allows a 1-hour reduction in the fire-resistance rating of each wall in the double-wall assembly.  Thus, a 2-hour fire wall may be constructed using two 1-hour walls.

*****

In some articles about fire-resistive construction, the term “fire wall” is incorrectly applied to other fire-resistive assemblies used for passive fire protection, such as fire barriers, fire partitions, and smoke barriers.  Although these assemblies serve their respective purposes, the fire wall has a unique place in the passive fire protection arsenal; thus, when a fire wall is utilized in a building, the special requirements associated with fire walls need to be carefully studied and incorporated where applicable.  Another thing that some tend to overlook when using a fire wall is that it provides a side benefit of also creating a horizontal exit, provided the doors and refuge areas comply with Section 1025 (See The Code Corner No. 24, “Horizontal Exits”).

---

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

Applying the Building Code during Design: A Step-by-Step Process

“Quality is never an accident; it is always the result of intelligent effort.” 

John Ruskin, author and critic of art and architecture

Nobody likes to redo work that he or she has already completed.  However, time and again, some design professionals seem satisfied to let the building department review their designs and then make any corrections that are noted.  This may work well for very small projects, where the impact of a correction has minimal effect on the overall design.  Large, complex projects, on the other hand, will likely suffer delays and significant changes if code compliance errors are left for the building department to find.  For example, if the design professional for a multistory building miscalculated the occupant load on the low side for a restaurant on the top story, the error might require widening of stairs, or worse, the addition of another stair.

Checking or inspecting work after completion is referred to as quality control, or QC.  For construction, the Construction Specifications Institute (CSI) defines quality control as the “procedures for evaluating completed activities and elements of the design for conformance with the requirements.”  Although some design firms use the local building department to perform the QC review, other design firms may have internal reviews conducted at the end of document production either by in-house staff or third-party peer reviewers to perform the QC review.  However, relying only on QC to ensure a quality project is neither efficient nor cost effective—regardless of who performs the review.

To minimize errors at the completion of construction documents, design firms need to implement quality assurance, or QA, in their design process.  CSI defines quality assurance as the “procedures for guarding against defects and deficiencies before and during the execution of the work.”  In other words, it involves taking measures along the way to ensure that errors are eliminated, or at least minimized, by the time construction documents are completed.  Reviewing the building code and understanding how it will apply to a project is a step that must be taken as early as possible in the design process.

The application of the building code in a design QA process is different than the application of the building code in a plan review QC process.  The plan review QC process compares the completed design documents to the requirements of the building code—any inconsistency will result in a comment back to the design professional.  As a QA process, however, there is no design to compare with the building code.  Therefore, the building code becomes a “road map” to compliance, and as such, there are various paths to get from point A to point B.  The best path selected becomes the design team’s code compliance strategy.  Like the use of a road map for travel, the planned path for code compliance is not always the path actually taken—changes may be necessary as the design develops and more detail is added.

The Step-by-Step Process

The step-by-step process described below provides the designer with a logical sequence and timing for implementing code compliance during the design of the project.  The process is divided into the three phases that the American Institute of Architects (AIA) has established for typical design projects:  schematic design, design development, and construction documents.  If under contract to provide programming services, some of the early steps for the schematic design may be accomplished at the programming stage.  This process is only a suggestion, and some steps may start earlier if the design team elects to do so.

Please note that each step described below is not comprehensive; each step may include multiple sub-steps, which requires a basic understanding of the applicable code requirements.  Where available, a link is provided to another Code Corner article that will provide some detailed information on all or a portion of the step’s topic.¹

Schematic Design

Step 1:    Determine the applicable building code.  Many jurisdictions do not adopt the building code that is currently published, and many also publish amendments to the adopted code to cover local conditions and policies.  Using the actual building code that will be used for plan review during the design process is critical.

Step 2:    Obtain essential building data.  Gathering basic information about the project, such as building area and height, will affect the application of the building code.  Also, making basic decisions early in the process, such as whether a sprinkler system will be provided and the type of structural materials proposed, will factor in later steps.  (See The Code Corner No. 18)

Step 3:    Determine building’s occupancy group or groups.  Based on the owner’s programming requirements, a determination of the building’s primary occupancy group can be made.  If individual spaces are listed in the program, it could be established if the building will be a mixed occupancy.  (See The Code Corner No. 14)

Step 4:    Determine construction type based on anticipated construction materials.  If the building is constructed on wood-framed bearing walls, then the only option is Type V construction.  However, if the construction is noncombustible, then the design team has several alternatives for construction type, depending on the level of fire-resistance the team is willing to incorporate into the design. (See The Code Corner No. 15)

Step 5:    Determine how mixed uses and occupancies will be handled.  If multiple occupancy groups are identified in Step 3, then an initial decision needs to be made whether they will be treated as accessory, separated, or nonseparated occupancies, or a combination of these three.  (See The Code Corner No. 14)

Step 6:    Determine if any special use and occupancy requirements will apply.  Some projects may have features or uses that are not covered by the general requirements of the building code.  In the International Building Code (IBC), Chapter 4 covers these unique circumstances, such as stages and platforms, atria, high rises, parking garages, etc.  The design team should review this chapter to determine if any of these requirements apply to the project.  (See The Code Corner Nos. 13 and 30)

Step 7:    Determine allowable area and height.  Based on construction type (Step 4), occupancy group or groups (Step 3), and the method selected for mixed occupancies, if applicable, (Step 5), determine the allowable area.  Apply any increases for sprinkler system and frontage (if the building has not been situated on the site, determine what the expected increase could be; this can be adjusted later if necessary).  If actual area exceeds allowable, a change in construction type, the use of a sprinkler system (if not already considered), or the introduction of a fire wall into the design should be considered.  (See The Code Corner Nos. 16 and 17)

Step 8:    Calculate occupant load.  Based on preliminary floor areas, determine occupant loads for each floor level using occupant load factors in IBC Chapter 10.  (See The Code Corner No. 22)

Step 9:    Establish points of exit.  Using the occupant loads calculated in Step 8, determine the number of required exits for each floor level according to IBC Table 1021.1.  Only one exit may be required if conditions comply with Section 1021.2.  If more than one exit is required, ensure that at least two of the exits are separated in accordance with Section 1015.2.  (See The Code Corner No. 22)

Step 10:  Check egress pathways for travel distance, common path of egress travel, dead-end corridors, and accessible routes and egress.  Look at every pathway from each space to each exit to see if at least one path is less than the maximum travel distance required by IBC Section 1016.  Verify that every path does not have a common path that exceeds the maximum distances in IBC Section 1014.3.  If corridors are provided, verify that none have dead ends that are longer than the maximums in IBC Section 1018.4.  (See The Code Corner No. 29)

Step 11:  Determine fixture counts.  Using the occupant load calculated in Step 8, determine the number of plumbing fixtures according to the requirements of IBC Chapter 29.  (See The Code Corner No. 33)

Step 12:  Identify fire department access roads.  During this phase of design, the project should have a preliminary site plan to determine if sufficient access is provided for the fire department.  Fire access roads complying with Section 503 of the International Fire Code (IFC) may be necessary to ensure all sides of a building are within reach of firefighting capabilities.

Design Development

Step 13:  Confirm Steps 2 through 12.  During the review of schematic design documents, changes may have been suggested that require reevaluation before design development proceeds. 

Step 14:  Identify locations of fire-resistive assemblies and openings.  Based on construction type, allowable area, separation of occupancies, means of egress components, and other special code requirements, determine where fire-resistive construction is required and which openings require protection complying with IBC Chapter 7.    (See The Code Corner Nos. 2, 19, 34, and 35)

Step 15:  Develop exterior wall assemblies.  During this design phase, exterior wall assemblies are designed and evaluated, including the selection of materials.  Based on construction type and fire separation distance, exterior walls and openings may require some level of fire-resistive protection in accordance with IBC Chapter 7.  Additionally, energy efficiency in accordance with the International Energy Conservation Code (IECC) and water resistance of exterior walls per IBC Chapter 14 are also a concern.  (See The Code Corner No. 26)

Step 16:  Develop roof assemblies.  Similar to exterior walls, roof assemblies are also designed and evaluated during the design development phase to comply with IBC Chapter 15.  Roofing materials are analyzed for applicability and performance, and like other building materials, roofing needs to comply with the requirements of the building code.  (See The Code Corner No. 6)

Step 17:  Select finishes.  Interior finishes for floors, walls, and ceilings need to comply with several requirements, including fire and smoke performance characteristics of IBC Chapter 8 and sanitation requirements of IBC Chapter 12.  Floor finishes also need to address slip resistance as required by ANSI A117.1 and ADA Standards.  Although specific materials and colors may not be selected at this stage, minimum performance requirements should be at least identified at this point based on the use of each space.  (See The Code Corner No. 4)

Step 18:  Check egress widths.  Using occupant loads calculated in Step 8, exit points determined in Step 9, and means of egress paths determined in Step 10, establish the minimum widths of egress components.  (See The Code Corner No. 22)

Step 19:  Check accessibility requirements.  There are many factors associated with accessibility in the building code, and many of these directly affect building layout and floor area.  IBC Chapter 10 needs to be reviewed for accessible means of egress, and ANSI A117.1 and the ADA standards need to be reviewed for accessible routes and clearances, among many other requirements.

Step 20:  Integrate special requirements.  As identified in Step 6, requirements associated with the unique elements of the project need to be considered in greater detail.  Such requirements include seating layouts for assembly occupancies, construction related to stages and platforms, smoke control for atria, sound transmission for residential occupancies, energy efficiency for exterior envelope components, flood-resistant elements for projects in flood plains, and provisions specific for high rise buildings.  (See The Code Corner Nos. 11, 12, 13, and 30)

Construction Documents

Step 21:  Confirm Steps 2 through 20.  During the review of design development documents, changes may have been suggested that require reevaluation before starting the construction documents phase.

Step 22:  Integrate egress details.  Since means of egress is important, drawings and specifications need to address specific requirements of the egress system, such as door swings, door hardware, riser and tread dimensions, luminous markings, and design of handrails and guards.

Step 23:  Identify locations of safety glazing.  This is an area where there is some difference of opinion.  Some think that the glazing installer should know where safety glazing is required as long as the specifications indicate that safety glazing be provided where required by code.  Others believe that the drawings should explicitly show where safety glazing is required, which is required by some jurisdictions.  See IBC Section 2406 for safety glazing requirements.

Step 24:  Detail firestopping and fire-resistant joints.  If fire-resistive construction and assemblies are used on the project, the construction documents need to address how joints and penetrations in these building elements are handled per IBC Sections 713 and 714.  Policy varies between jurisdictions, but some jurisdictions only require approved systems be identified on the documents, while others require the full content of approved systems be shown on the drawings.  (See The Code Corner No. 23)

Step 25:  Locate portable fire extinguishers and cabinets.  Fire extinguishers are often overlooked until either the last minute or during construction.  Unless a sprinkler system with quick response sprinklers is installed, fire extinguishers are required in most occupancy groups per IBC Section 906.  (See The Code Corner No. 32)

Step 26:  Detail construction based on specific building materials and equipment.  This is a broad step that covers a multitude of sub-steps—each with a varying degree of applicability depending on project requirements.  Drawings and specifications need to address specific material and construction requirements in the code, such as those for concrete, masonry, steel, wood, plaster, gypsum board, plastics, and elevators.

Step 27:  Prepare code information sheets.  This step may be started at any time that information is available; however, this is the last step that needs to be performed in order to have a complete set of submittal documents for the building department.  The code information sheets provide all the essential code-related information in a single location in the set of drawings.  It allows the plans examiner to confirm compliance without having to conduct an extensive and time consuming review of the drawings.

As John Ruskin’s quote emphasizes, achieving quality in a building project is a deliberate process that must be implemented by the design team at the earliest possible phase of the project.  Although quality in building design implies more than just complying with building code requirements, it is the safeguarding of “public health, safety and general welfare”—the intent of building codes—that is directly tied to the design professional’s license to practice.  Therefore, design professionals should incorporate into office practice a quality assurance process that covers building code-related issues. 

---

¹  References to the International Codes used in this article are for the 2009 editions.  However, The Code Corner articles referenced may be based on older editions of the International Codes.  It is suggested that the reader compare information in past articles to the current code editions used in this article.

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.

---

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.”