4
Special Detailed
Requirements Based on Occupancy and Use
In addition to the requirements for typical occupancies, the code addresses detailed requirements for specific building types in Chapter 4. The occupancy of these buildings usually fits into one or more of the typical occupancy groups, but characteristics of these building types require additional code provisions. Examples of such building types are covered and open mall buildings, high-rise buildings, and atriums. A mall is basically a Group M occupancy, but with many stores, large occupant loads, and means of egress that also serve as pedestrian walkways. High-rise buildings are typically Group B or R occupancies with very large occupant loads and are defined as having occupied floors located above fire department ladder access. Atriums have large interior volumes open to pedestrian pathways and to occupied spaces. These buildings need added code consideration above and beyond more typical uses in the same occupancy group. The additional code requirements for these building types are determined by their configurations, not their uses.
The development of new types of buildings often happens in advance of code provisions specific to them. Code officials must respond to requests by owners to build such structures by addressing them on a case-by-case basis. As these new types of buildings or new uses become more prevalent, the code responds by collecting information about how different jurisdictions have addressed these new buildings. Then the code-development process generates new code provisions to address them. These provisions are meant to apply over and above the other provisions applicable to their occupancy group classification. After the designer has classified the building by occupancy, the building type must then be examined to see if it meets the definitions for these specialized use groups and thus must also meet the added criteria for them. The process of analysis of use and occupancy should commence with an analysis of how the proposed building fits into the uses and occupancies described in Chapter 3 of the code, and then should be analyzed against the criteria in Chapter 4 to see which, if any, are applicable.
Special Detailed Requirements Based on Occupancy and Use
It is worth remembering that the detailed provisions of Chapter 4 of the code relate to and coordinate with the more basic requirements spelled out in Chapter 3 for use and occupancy requirements. The designer as code user should make a progression from the general to the specific in analyzing a building. Begin with the general categorization of uses and occupancies. Then proceed to review the detailed requirements of Chapter 4 for provisions applicable to the building in question. While one may begin the analysis of a specialized use by looking up the detailed requirements, the code is organized to proceed from determining the occupancy first and then applying detailed criteria. Just as one should not read up from footnotes to find table sections that may be misapplied, the user should not work backward in these analyses, as this may lead to erroneous code interpretations.
We will go through the specialized building types to describe their distinguishing criteria and touch on the major additional code provisions applicable to them. We will discuss those special uses most likely to be encountered by designers. Note that several very specialized uses have been omitted, as they are not seen frequently. Most are related to Group H Occupancies or to process-related special uses. Most designers do not frequently encounter these very specialized structures, or others such as underground buildings or amusement buildings. The criteria applicable to each of these other building types are used as noted above. The occupancy must first be determined before applying the specialized requirements contained in Chapter 4.
Many of the sections in Chapter 4 contain definitions of the uses or occupancies to which the special provisions apply. These definitions are listed in Chapter 2 of the code and cross-referenced for location and explanation in the section indicated. Note that although the definitions may seem familiar and similar to common construction terminology, they have very specific meanings in the code. Examine the building design conditions and definitions carefully to determine the applicability of the definition to the building design. This analysis of the definition may also point out necessary modifications to the design to make it code-compliant or reveal the need to reclassify it.
Institutional Groups I-2 and I-3
The code adds provisions related to Group I-2 occupancies in § 407 and Group I-3 occupancies in § 408 that must be read in concert with those in Chapter 3. Chapter 3 is intended to address the occupancy classification of a building, and Chapter 4 is intended to address detailed requirements for certain uses and occupancies. Code analysis of these occupancy groups requires looking at both sets of provisions together. These are very specialized occupancies with many specific and detailed requirements. The discussion in this chapter of the special requirements for these occupancies is only an introduction. The code user must consult the detailed requirements in the IBC to determine the specific requirements for a specific project.
Other Specialized Uses
The remaining groups of uses in Chapter 4, beyond those discussed in this chapter, relate to specific uses of buildings or parts of buildings that are infrequently encountered in most occupancies. These include motion-picture projection rooms, stages and platforms, special amusement buildings, aircraft-related facilities, and high-piled combustible storage. These are specialized uses not often encountered in the normal course of work and will not be addressed in this book.
Covered and Open Mall Buildings
The code provisions in § 402 for covered mall buildings grew out of many years of application of special interpretations of existing codes in response to a then-new building type. It did not fit into the code criteria in use at the time this use type was first developing. Covered malls came into being based on design and retailing innovations. They combine the circulation paths used for means of egress with pedestrian routes. Spaces that might be considered exit discharge areas or safe egress terminations, such as a city street, became exit access areas with enclosures. Multiple tenants have access to the common pedestrian areas. There is a mixture of large department store type uses, termed “anchor” buildings, and smaller shops that open on the mall. It is also expected that there may be a mixture of other uses such as cinema and food court assembly areas as well as major anchor uses that are interconnected by the mall.
The 2009 IBC added language clarifying that the term Covered Mall Building is intended to also include open malls, which are defined as “unroofed common pedestrian ways serving two or more tenants and which do not have more than 3 levels open to each other.” Thus an open mall is essentially the same as a covered mall, but without a cover over the mall circulation spaces. The open mall is flanked by “open mall buildings,” which, as for covered malls, do not include anchor buildings.
New language was added in the 2012 IBC to clarify that open malls using the provisions of § 402 are to be treated in a similar manner to covered malls in how they relate to means of egress and major stores.
- An open mall is an unroofed common pedestrian way serving multiple tenants and not exceeding three levels.
- Gross leasable area (GLA) is the total floor area available for tenant occupancy, measured from the centerlines of joint partitions to the outside of tenant walls. All tenant areas, including areas used for storage, are to be included in the GLA.
Example for Determining Occupant Load per § 402.8.2
Assume:
Retail Gross Leasable Area (GLA) = 200,000 sf(18 580 m2)- + A food court having an area of 5000 sf (465 m2)
- + An assembly use with fixed seating for 500 (included in the 200,000 sf (18 580 m2) of the GLA)
To determine the Occupant Load Factor (OLF) for the mall, use Equation 4-1:
- OLF = (0.00007) (GLA) + 25
- OLF = (0.00007) (200,000) + 25= 39 sf (3.62 m2) per occupant
To determine the occupancy of the food court, use Table 1004.1.2 and allow 15 sf (1.39 m2) net per occupant in the food court seating area (Assembly without fixed seats, unconcentrated, with tables and chairs):
- 5000 sf/15 sf (465 m2/1.39 m2) per occupant= 334 occupants
Total Occupant Load:
- = (200,000/39) + 334
- = 5129 + 334 = 5463 occupants
The code provisions for covered and open malls rely on several basic ideas:
- First is the provision of multiple clear paths of exit with widths sufficient to accommodate the occupant load, which is calculated according to criteria in this section.
- Second is the requirement that the increased building area be offset by separation from other buildings by at least 60' (18 288) of permanent open space to allow safe egress areas for occupants. This permanent open space allows covered mall and anchor buildings to have unlimited area for all but Type V construction. Note that the open space may be reduced under certain conditions as illustrated below.
- Third is the requirement that potentially hazardous uses such as parking structures be separated from the mall, either by a minimum distance or by construction type (fire barrier with a fire-resistance rating of 2 hours).
- Fourth is a requirement for provision of active fire protection in the form of sprinklers, standby power, and a central fire department operations area.
High-Rise Buildings
As building technology allowed advances in high-rise construction, the buildings often outstripped code provisions needed to address the new conditions impacting fire and life safety. High-rise buildings, made possible by innovative structural technology and elevators for transporting occupants, exceed the capabilities of firefighting procedures used for shorter buildings. They have occupied floors above the reach of even the longest ladders carried by fire department vehicles.
Note that high-rise egress systems are based on the occupant loads and egress requirements spelled out elsewhere in the code (see Chapter 10). Stairways are the primary means of egress, with elevators typically serving only firefighting functions as necessary. There are currently no refuge-area requirements in the code for harboring occupants not able to reach the stairway systems, other than requirements for areas of refuge for persons with disabilities where required by sections of the code found in Chapter 10.
With the advent of ever-taller buildings and in light of lessons learned from the September 11, 2001, World Trade Center disaster, a subset of requirements for “super high-rise” buildings, which are those taller than 420' (128 m) in height, has been added to the IBC. Most of these provisions are found in § 403 but many others are scattered throughout the code, most notably in Chapter 10, where additional means-of-egress provisions are required in such buildings. We will highlight these provisions with a notation where they apply to our discussion or illustrations.
Note that requirements for “Fire Service Access Elevators” for buildings more than 120' (36 576) in height are found in Chapter 30.
Note also that due to their limitations on heights and not being part of a mixed-use occupancy, buildings with Group H-1, H-2, and H-3 occupancies are excepted from the provisions in § 403, since in practical terms they will never be present in a high-rise structure.
Reduction in Fire-Resistance Rating per § 403.2.1
Atriums
Atriums were an innovative building type that required a specific building-code response as their use became more prevalent. The code requirements in § 404 for atriums combine aspects of malls and high-rise fire and life safety provisions.
As for covered malls and high-rise buildings, the code requires that a mixture of active and passive fire-protection measures be provided in atriums. Atrium buildings, however, rely more heavily on active systems for fire and life safety.
- The travel distance through the atrium cannot exceed 200' (60 960).
- Buildings containing atriums must be fully sprinklered throughout the building. There are limited exceptions to § 404.3 for certain areas, but the basic design assumption should be that such buildings are fully sprinklered.
- Openings into the atrium may be glazed if special fire-sprinkler protection is provided.
The greatest concern about atrium fire and life safety involves the control of smoke. Atriums that connect more than two stories are required to have smoke management systems conforming to § 909. These interconnect elaborate systems of detectors, fans, and controls to contain or move smoke to allow safe egress for occupants of atriums.
Motor-Vehicle-Related Occupancies
Building codes have traditionally had a great deal of difficulty classifying and addressing parking structures and garages. There is a longstanding perception among code writers that there are inherent dangers for vehicles carrying flammable fuels and emitting noxious gases. Yet buildings housing these types of uses have had a generally good safety record. Because of special concerns regarding these occupancies expressed in predecessor codes, § 406 has grouped these uses into a separate category that can be considered a distinct occupancy group.
Revisions to § 406 place all of the general requirements for motor-vehicle-related occupancies into a single group at the front of the section. Items that are common for all the various uses covered by this section, and which used to appear in each subsection, are now stated once in the various subsections in § 406.2.
The common criteria are meant to apply to the many varied uses covered by this section: private garages and carports; public parking garages, whether open or enclosed; and fuel dispensing stations and repair garages. Note that there are some special conditions in the subsections that will augment the general provisions discussed here.
§ 406.2.1 Automatic Garage Door Openers and Automatic Gates
This subsection highlights the broad range of applications for § 406.2. These provisions are applicable to quite different uses, ranging from single-family home garages to multistory public parking garages.
§ 406.2.2 Clear Height
The clear height of each floor level in vehicle and pedestrian traffic areas in all motor-vehicle-related uses is to be not less than 7' (2134). Canopies under which fuels are dispensed are to have a taller clear height in accordance with § 406.7.2.
Note that in parking garages serving van accessible parking, 98'' (2489) clearance is required per Standard ICC A117.1, which is adapted into IBC Chapter 11.
§ 406.2.3 Accessible Parking Spaces
Where accessible parking is required, accessible parking spaces, access aisles, and vehicular routes serving accessible parking are to be provided in accordance with § 1106.
Stall dimensions will be as required by Standard ICC A117.1.
§ 406.2.4 Floor Surfaces
Floor surfaces are to be of concrete or similar noncombustible and nonabsorbent materials. Floors areas used for parking are to be sloped to facilitate the movement of liquids to a drain or toward the main vehicle entry doorway. The surface of vehicle fueling pads in motor-fuel-dispensing facilities are to be in accordance with § 406.7.1.
Exceptions to § 406.2.4:
- Asphalt parking surfaces are permitted at the ground level in public parking garages and private carports.
- Floors of Group S-2 open or enclosed parking garages are not required to have a sloped surface.
- Slip-resistant, nonabsorbent, interior floor finishes meeting certain finish criteria are permitted in repair garages.
§ 406.2.5 Sleeping Rooms
Openings between a motor-vehicle-related occupancy and a room used for sleeping are not permitted.
§ 406.2.6 Fuel Dispensing
The dispensing of fuel is only permitted in motor fuel–dispensing facilities that are in accordance with § 406.7. If there are conflicts between § 406.2.6 and § 406.7, the requirements of § 406.7 are more specific to the proposed use and are to govern.
§ 406.2.7 Electric Vehicle Charging Stations
This is a new section recognizing the increased presence of electric vehicles (EV). This is to address how to treat them, if provided. It does not require them. Where provided, electric vehicle charging stations are to be installed in accordance with NFPA 70 and are to be listed and labeled in accordance with UL 2202 and UL 2594. Accessibility to electric vehicle charging stations is to be provided in accordance with Chapter 11.
§ 406.2.9 Equipment and Appliances
Equipment and appliance requirements that were previously included with each motor-vehicle use have been consolidated into this section. Additional requirements are to be found in the International Mechanical Code and the International Fuel Gas Code.
§ 406.2.9.1 Elevation of Ignition Sources
Equipment and appliances having an ignition source and located in the uses covered by § 406 are to have the ignition source elevated such that the source of ignition is not less than 18'' (457) above the floor. For the purpose of this section, rooms or spaces that are not part of the living space of a dwelling unit and that communicate directly with a private garage through openings shall be considered to be part of the private garage. Per an exception, elevation of the ignition source is not required for appliances that are listed as being flammable-vapor ignition resistant.
§ 406.2.9.1.1 Parking Garages
Connection of a parking garage, which would include residential parking garages and open and enclosed parking garages, to a room in which there is a fuel-fired appliance, is to be by means of a vestibule providing a two-doorway separation, except that a single door is permitted where the sources of ignition in the appliance are elevated in accordance with § 406.2.9. Compliance with that section would include appliances not needing elevation since they meet the exception by being listed as flammable-vapor ignition resistant. This requirement is not applicable to overhead appliance installations complying with § 406.2.9.2 or § 406.2.9.3.
Motor-vehicle-related uses break down into four general categories:
- Private garages or carports
- Public parking garages
- Open parking garages
- Enclosed parking garages
- Motor-fuel dispensing stations
- Repair garages
Private Garages and Carports
Private garages or carports are for private use and meet the common definition of what we all think of as parking for housing. These are typically considered Group U occupancies. Separation requirements are contained in Chapter 4, § 406.3.4. Note that one- and two-family dwellings and their accessory structures such as garages are intended to be regulated by the International Residential Code.
- An enclosed garage abutting a house is to have a minimum of one layer of ½'' (12.7) gypsum board on the garage side. Where rooms extend over the garage a minimum of ⅝'' (15.9) type-X gypsum board is to be used at the ceiling for separation.
- Doors between the garage and house are to be solid wood or solid-core doors at least 1 ⅜'' (35) thick or complying with § 716.5.3.
- Door is to be self-closing and self-latching.
Parking Garages
§ 406.4 classifies public parking garages into open parking garages and enclosed parking garages.
Open Parking Garages
Open parking garages are multiple-vehicle facilities used for parking or the storage of vehicles where no repairs take place. These are typically classified as Group S-2 occupancies. They are to be of Types I, II, or IV construction per § 406.5.1. To meet this definition, the amount and distribution of openings are specified in § 406.5.2 of the code. Because these openings are distributed in a manner that provides cross-ventilation for the parking tiers, no mechanical ventilation is required.
Enclosed Parking Garages
Enclosed parking garages are similar to open parking garages except that the amount of wall enclosure relative to the building area does not allow them to be considered as open garages. Because they do not meet the criteria for open parking garages and are considered enclosed, mechanical ventilation is required to compensate for the lack of cross-ventilation.
Motor-Fuel Dispensing Facilities
These uses include motor-vehicle “service stations,” which are typically freestanding structures and are considered as Group M occupancies. Note the references to the Fire Code in which additional construction detail requirements are contained.
Group I-2 Occupancies
Group I-2 occupancies include nursing homes and hospitals. Such occupancies serve populations that are not capable of self-preservation in an emergency and who will either require evacuation assistance or a “defend in place” egress strategy. Hospitals are very complex buildings that have extensive code requirements that need to be met by experienced designers. We will not touch on them in this book. However, Group I-2 Condition 1 occupancies include foster care homes and nursing homes, which many more design professionals may be engaged to design. We discuss here several examples of the specialized requirements for these uses to highlight how Chapter 4 must be consulted for information regarding the specific occupancies addressed in this chapter.
§ 407.2.1 Corridors and Waiting Areas in Any Group I-2 Occupancy
§ 407.2.5 Nursing Home Housing Units
[Group I-2, Condition 1 only: Nursing Homes and Foster Care Facilities]
§ 407.2.6 Cooking Facilities
[Group I-2, Condition 1 only: Nursing Homes and Foster Care Facilities]
Although not explicitly stated, assume corridor wall construction extends around the dining area as a space meeting the requirements of § 407.2.5.
Live-Work Units
§ 419 of the code addresses requirements for live-work units, which are classified as an R-2 occupancy.
Separations in H, R-1, R-2, R-3, and R-4 Occupancies
In either nonseparated occupancies per § 508.3 or separated occupancies per § 508.4, there is still a requirement to provide separations at dwelling units, sleeping units, and supervised residential facilities. § 420 contains these requirements.
Health Care Clinics
Health Care Clinics
While health care clinics are a specialized use, the occupancy classification and application of code provisions to health clinics is often the subject of misunderstanding between project proponents and the AHJ. We have therefore included a discussion of the distinctions between the requirements for Ambulatory Care Facilities, discussed in the new § 422 of the IBC, and other types of clinics. Ambulatory Care Facilities, often called “outpatient surgical centers,” often perform relatively complex surgical procedures, where patients are rendered unconsious during the procedure but go home in less than twenty-four hours; the facilities therefore do not function as hospitals. New code provisions have been written to address the increasing construction and operation of such facilities.
Ambulatory Care Facilities
§ 422 contains special provisions for ambulatory care facilities based on the assumption that occupants may not be able to leave without assistance and thus need additional protection:
Storm Shelters
In areas subject to high winds, such as tornadoes or hurricanes as described in the code, storm shelters are often desirable additions to buildings as a voluntary measure. If they are provided, such rooms or spaces are to comply with “ICC 500,” the ICC/NSSA Standard for the Design and Construction of Storm Shelters. This section applies to storm shelters constructed as separate detached buildings or as rooms or spaces within buildings. It is important to keep in mind that these rooms or spaces are for temporary shelter from a tornado or hurricane. They are NOT intended to serve as long-term emergency shelters after a wind event unless they are designed per “Risk Category IV” buildings per Table 1604.5.
The provision of such shelters is mandatory for E occupancy schools with more than 50 occupants. The room or space that is to be provided must be sized to include all of the buildings on the site and shall be the greater of the following: the total occupant load of the classrooms, vocational rooms, and offices in the Group E occupancy, or the occupant load of any indoor assembly space that is associated with the Group E occupancy.
