Assignment

CHAPTER 3

OCCUPANCY CLASSIFICATIONS AND LOADS The occupancy classification

of a building or space is generally determined by the way that building or space is

to be used. Occupancy classifications have been developed by the codes to address

the different hazardous situations, often referred to as risk factors, associated with

each type of use. These risk factors consider the typical characteristics of the

environment, the activity that will occur in the space, and the occupants using the

space. Risk factors may include spatial characteristics (low light levels, fixed

seating, and high sound levels), fuel loads (amount of finish materials, upholstered

furniture, and other flammable contents), concentration of occupants,

characteristics of the occupants (mobility, age, alertness), and sometimes the

familiarity of the occupants with the building. In some cases, these unique

characteristics call for additional code requirements so that buildings are safe. For

example, more exits are required in auditoriums (Assembly) due to the large

number of people using the space, and alternate exiting methods are required in

hospitals (Institutional), where occupants often are not mobile due to age, health,

or security reasons. The different occupancy classifications in the codes are based

on these various characteristics. The codes address these conditions for each

occupancy classification so that people can be considered equally safe at work, at a

crowded concert, or with any other type of use. In some cases, the projected

occupant load (OL) will be the most influential component in determining the

occupancy classification. The occupant load is the number of people that is

assumed to safely occupy a space or building. Since occupancy classifications and

occupant loads are, in a sense, dependent on each other, both should be considered

at the beginning of a project. Once the occupancy classification has been

determined, the projected occupant load, or expected number of people, is used to

determine a number of other code requirements. The first part of this chapter

concentrates on occupancy classifications and their relationships; occupant loads

are discussed in the last part of the chapter. UNDERSTANDING OCCUPANCY

CLASSIFICATIONS An occupancy classification must be assigned to every

building or space within a building. Determining the occupancy classification is

one of the most important steps in the code process. It should be the first thing

determined when designing the interior of a building, since almost every interior

code and regulation is based on the

Kennon, Katherine E.; Harmon, Sharon K.. The Codes Guidebook for Interiors

(pp. 131-132). Wiley. Kindle Edition.

building's occupancy. Many examples are listed in Figure 3.1. The occupancy of a

space must also be known in order to effectively use most of the remaining

chapters in this book. Once the occupancy is known, it will guide the remaining

code research. Accessibility Requirements Fire Extinguishing Systems Alarm

Systems Furniture Selection/Placement Egress Capacities Means of Egress

Electrical Devices Mechanical Loads Emergency Lighting Occupant Loads Finish

Selection/Placement Plumbing Fixtures Fire Barriers/Partitions Smoke Barriers

Fire/Smoke Detection Systems Smoke Detection Systems Figure 3.1 Interior codes

affected by occupancy. For existing buildings that are occupied, the occupancy

classification is already determined. But for a new or existing building that is

intended to have new tenants, the occupancy classification for each proposed

tenant must be determined separately. These different tenants may, in turn, affect

the way the shared public spaces are classified. The occupancy classification must

be reexamined whenever changes are made in the use of a building or space. If the

intended use of an existing building is changing significantly, determining the new

occupancy classification may be particularly important. Some of these changes are

obvious, such as an old warehouse building being renovated into apartments. Other

changes may be less noticeable but still require reclassification. It may also be

important to understand how the occupants will actually be using the space or plan

to use it in the future. For example, if a space will be used temporarily as an open

office plan but in the future will be used as a training room, both Assembly and

Business requirements may have to be considered so that the design will address

the most stringent code requirements. If not, significant renovations may be

required when the change in use actually occurs. The ICC codes and the NFPA

codes divide the occupancy classifications slightly differently. However, the 10

most common occupancy classifications used throughout the various building and

life safety codes are listed here. Some of them also have subclassifications. The

occupancy classifications and their subcategories are discussed in the first part of

this chapter. Assembly occupancies

Kennon, Katherine E.; Harmon, Sharon K.. The Codes Guidebook for Interiors

(pp. 132-133). Wiley. Kindle Edition.

Business occupancies Educational occupancies Factory or Industrial occupancies

Hazardous occupancies Institutional occupancies Mercantile occupancies

Residential occupancies Storage occupancies Utility or Miscellaneous occupancies

Many of these classifications seem self‐explanatory, especially if a building type is

straightforward, but remember that three things must be known before the

occupancy classification can be accurately determined: (1) the type of activity

occurring, (2) the expected number of occupants, and (3) whether any unusual

hazards or risk factors are present. These factors can affect the appropriate

classification of a building type or spaces within a building. A boutique that sells

clothing, for example, has an activity that is straightforward. It is a Mercantile

occupancy. However, in some cases, small differences in use can change the

occupancy classification. For example, a television studio is a Business occupancy,

but if the studio allows audience viewing, it will typically be considered an

Assembly occupancy. Knowing the specific type(s) of activities that are occurring

is important. Many of the classifications allow for a specific number of people. For

example, a space may appear to be an Assembly use, but if a small number of

people will be using the space, it may be allowed to be classified as Business.

When using the IBC, if a day care center serves fewer than five children, it may be

considered Residential, but if it has more than five attendees, it may be considered

Institutional or Educational. So, if the number of occupants increase or decrease,

the occupancy classification may have to be reexamined. Hazards to occupants can

include harmful substances and/or potentially harmful situations. (See the inset

titled “Risk Factors and Hazards in Occupancies” in this chapter.) When either is

present, different types of requirements apply. The storage or use of flammable,

explosive, or toxic materials is considered to be hazardous and can either change

the occupancy to a stricter classification or require all or part of a building to be

classified as a Hazardous occupancy and be subject to tougher codes. Small levels

of certain hazardous materials, however, are allowed in almost every occupancy

classification. For example, a small amount of paint can be stored

Kennon, Katherine E.; Harmon, Sharon K.. The Codes Guidebook for Interiors

(pp. 133-134). Wiley. Kindle Edition.

in any occupancy. However, in large amounts paint storage would be considered a

Hazardous use. Certain situations within a building or the condition of the

occupants themselves can create potential risk factors or hazards as well. Low light

levels, low awareness or mental capacity, restricted movement due to security, and

similar characteristics can create potentially unsafe situations. If hazardous

materials or situations are expected to be present in the building or space, it may

affect the appropriate choice of occupancy classification. Consult the local code

official early in a project whenever there is uncertainty as to the correct occupancy

classification. It is always a good idea to have a code official confirm the choice of

occupancy. If it is determined later that the choice is incorrect, or if the choice is

not approved by the code official, the rest of the research may be incorrect and the

design may not meet the appropriate code requirements. COMPARING THE

CODES The building codes, such as the International Building Code (IBC) and the

Life Safety Code (LSC), are used to assign an occupancy classification to the uses

of a space or building. Knowing the appropriate occupancy classification and/or

subclassification is the most important step in understanding what code and

standard requirements apply to a space or building. Most of the requirements and a

majority of the exceptions are based on occupancy. Also, since the NFPA codes

are organized largely by individual occupancy chapters, the correct occupancy

classification is necessary to determine the appropriate chapter to apply to the

project. Other codes also use the occupancy classifications to call out particular

code requirements. This includes the fire codes, such as the International Fire Code

(IFC), which provides specific fire‐related requirements for each occupancy type

within its various chapters. The fire codes provide additional requirements for

other special uses as well. This includes unusual buildings and rooms that might

not be covered in the building codes. Because these uses have unique activities or

hazards associated with them, special requirements are called out by separate

chapters or sections within the fire codes. For example, the fire codes typically

have chapters on airports, clean rooms in laboratories, and rooms used for dry

cleaning. If there is a special use in a particular design, research both the building

code and the fire code when it is required by a jurisdiction.

Kennon, Katherine E.; Harmon, Sharon K.. The Codes Guidebook for Interiors

(pp. 134-135). Wiley. Kindle Edition.

RISK FACTORS AND HAZARDS IN OCCUPANCIES The types of risk factors

or hazards found in a building help to determine its occupancy classification. They

can vary dramatically from one building type to the next. Each occupancy type was

created to handle different types of hazards. Some of the risk factors that are

typically considered when determining an occupancy classification are: Number of

occupants (a large group versus a small gathering) If occupants are at rest or

sleeping Alertness of the occupants (considers mental capabilities and inherent

distractions caused by the activities going on in the space) Mobility of the

occupants (considers physical abilities, age, and security measures) Familiarity of

occupants with the space or building Typical characteristics of the space used for a

particular activity (includes fixed seating and aisles, light levels, noise levels, etc.)

Potential for spread of fire (due to airborne flammable particles, storage of

hazardous materials, combustible finishes, decoration or contents, etc.) These risk

factors were considered by the code organizations in the development of each

occupancy classification, the various subcategories, and the appropriate code

requirements. It may also be necessary to consider if any of these factors are

specifically known to exist within the proposed space. Both the occupants in the

space and the use of the space must be considered to correctly determine the

occupancy classification. Similar risk factors must also be considered when

working with performance codes. The assigning of occupancy classifications by

the codes allows some assumptions to be made as to how people will react and

move within a space or building in case of a fire or emergency. The prescriptive

requirements then define specifically how safety can be achieved. By contrast,

when using performance codes, only general parameters for what should be

considered about the activities and the occupants are given by the codes. The

design must then describe and/or prove how safety is provided. Therefore, if there

is an unusual building type or an occupancy with multiple uses, use of performance

criteria may have to be considered (if allowed by the jurisdiction). Note Most code

jurisdictions require the use of a fire code in addition to a building code. Typically,

the fire code will be either the International Fire Code or the NFPA Fire Code

(NFPA 1). The ICC Performance Code (ICCPC) has a section titled “Use and

Occupancy Classification” within the “Design Performance Levels” chapter.

Instead of grouping types of activities into occupancy classifications, it states that

the objective is to identify the primary use of a space or building and the risk

factors associated with that use. The risk factors that must be considered include

the type of activity, hazards, number of occupants, length of occupancy, alertness

(sleeping or awake), familiarity with the space, vulnerability (lack of mobility or

cognitive awareness), and whether occupants are related. The NFPA codes discuss

similar issues that should be considered by discussing occupant characteristics and

assumptions within the “Performance‐based Option” chapter in each code. The

design must then take into account the unique characteristics of the use and

occupants. Because accessibility requirements apply to almost every occupancy

classification or building use, the necessary accessibility documents must be

referenced. The building codes include an accessibility chapter and refer to the

accessibility standard ICC A117.1. Depending on the building type, the Americans

with Disabilities Act (ADA) standards or the FHA Accessibility Guidelines

(FHAG) may be required as well. In some cases, specific building types will be

subject to additional requirements. For example, the ADA Standards have

requirements that must be met for certain occupancies, such as Mercantile,

Residential, and Health Care. Other building uses may be exempt. (See the section

“Accessibility Requirements” later in this chapter and Chapter 2 for more

information.) DESCRIPTION OF OCCUPANCIES Use the following description

of each occupancy to help determine the occupancy classification of a space or

building. In addition, an occupancy may be subdivided into smaller, more specific

categories. For example, the IBC divides its Assembly occupancy into five

different subclassifications. These subclassifications are explained as well. A wide

range of common building types has been provided as examples. The list is not all‐

inclusive, and it does not replace the applicable code publications. These must be

referenced as well. Each code also classifies its occupancies a little differently. For

example, the classifications used in this chapter are based on the ICC's I‐Codes.

Although many are similar to those used in the NFPA codes, the NFPA may use a

different name for a classification or subdivide them differently. Refer to Figure

3.2 for a comparison of how each occupancy classification differs in the IBC and

the NFPA codes. OccupancyClassification ICCInternational Building Code

NFPALife Safety Code and NFPA 5000 ASSEMBLY A‐1 Assembly, Theaters

(Fixed Seats) A Assembly (variations noted by occupant load) A‐2 Assembly,

Food and/or Drink Consumption A‐3 Assembly, Worship, Recreation, Amusement

A‐4 Assembly, Indoor Sporting Events A‐5 Assembly, Outdoor Activities

BUSINESS B Business B Business AHC Ambulatory Health Care

EDUCATIONAL E Educational (includes some day care) E Educational

FACTORY/INDUSTRIAL F‐1 Factory Industrial, Moderate Hazard I Industrial,

General F‐2 Factory Industrial, Low Hazard Industrial, Special Purpose Industrial,

High Hazard HAZARDOUS H‐1 Hazardous, Detonation Hazard (included in

Group I) H‐2 Hazardous, Deflagration Hazard or Accelerated Burning H‐3

Hazardous, Physical or Combustible Hazard H‐4 Hazardous, Health Hazard H‐5

Hazardous, Hazardous Production Materials (HPM) INSTITUTIONAL I‐1

Institutional, Custodial Care OL* >16 D‐I Detentional/Correctional (includes

various subconditions IV) I‐2 Institutional, Medical Care H Health Care I‐3

Institutional, Restrained (includes various subconditions I5) DC Day Care I‐4

Institutional, Day Care Facilities MERCANTILE M Mercantile M‐A Mercantile, >

3 levels or > 30,000 SF (2800 SM) M‐B Mercantile, ≤ 3 stories or > 3000 SF (280

SM) and ≤ 30,000 SF (2800 SM) M‐C Mercantile, 1 story ≤ 3000 SF (280 SM)

RESIDENTIAL R‐1 Residential, Transient R Residential, Hotels and Dormitories

R‐2 Residential, Multi‐Dwelling Unit Residential, Apartment Buildings R‐3

Residential, One and Two Dwelling Units Residential, Lodging or Rooming

Houses Residential, One‐ and Two‐Family Dwellings R‐4 Residential, Care and

Assisted Living Facilities OL > 5 ≤16 Residential, Board and Care STORAGE S‐1

Storage, Moderate Hazard S Storage S‐2 Storage, Low Hazard UTILITY/

MISCELLANEOUS U Utility and Miscellaneous Special Structures and High‐

Rise Buildings Figure 3.2 Comparison of occupancy classifications. (This chart is a

summary of information contained in the 2015 editions of the International

Building Code®, the NFPA 5000®, and the Life Safety Code®. Neither the ICC

nor the NFPA assumes responsibility for the accuracy or completeness of this

chart.) Note Letters are often used to designate an occupancy classification. For

example, “A” stands for Assembly and “E” stands for Educational. (See Figure

3.2.) Assembly (A) Occupancy A building or part of a building is classified as an

Assembly occupancy if people gather for civic, social, or religious functions,

recreation, entertainment, eating, drinking, or awaiting transportation. The most

common characteristic of an Assembly occupancy is that it holds a large number of

people (usually more than 50) who are unfamiliar with the space. Other common

characteristics include such aspects as low light levels, the occupants' lack of

awareness of surroundings, and the potential for panic because of the number of

occupants. Because of these multiple risk factors, there are a number of additional

codes that apply strictly to Assembly occupancies. Note A restaurant can be

classified as a Business or Mercantile occupancy (if the number of occupants is

small enough), as an Assembly, or as an accessory to a larger adjacent occupancy.

The NFPA codes rely primarily on the number of people to determine the

classification of an Assembly. The IBC bases its classifications more on the type of

activity than on the density of occupants. As a result, NFPA codes have fewer

Assembly subclassifications. (See Figure 3.2.) Each code also provides specific

requirements for unique uses such as malls, theaters with stages, and other building

types that may seem to fit the Assembly use. In the IBC this information is in a

separate special‐use chapter; in the NFPA codes it is included in the Assembly

occupancy chapters. The IBC has five subclassifications of Assembly based on the

type of activity occurring. They are designated as A‐1 through A‐5. A‐1 This type

is for the viewing of performing arts or movies. The space often includes a stage.

(There are many code requirements specifically for stages.) The common

characteristics of these types of spaces are low light levels and above‐normal

sound levels. Seating usually consists of fixed seating with well‐defined aisles.

Occupants are alert but distracted and generally unfamiliar with the building.

Sample Building Types Motion picture theaters Radio and television studios with

audiences Symphony and concert halls Theaters for stage production A‐2 This type

is for the consumption of food and drink. Often these spaces have low light levels,

loud music, late operating hours, and ill‐defined aisles (e.g., movable tables and

chairs). The serving of food and drink is the most defining characteristic. Sample

Building Types Banquet halls Casino gaming areas Dance halls (serving food and

drink) Drinking establishments Fast‐food restaurants Fellowship halls (serving

food and drink) Nightclubs Restaurants (including kitchen; may also be classified

as Business) Taverns and bars (may also be classified as Business) Commercial

kitchens (associated with a dining area) A‐3 This type is for the gathering of

people for worship, recreation, or amusement. Types of activities that are not

classified by other types of Assembly are typically included in this

subclassification. The common characteristics of this subclassification are clear or

defined egress patterns and moderate to low fuel loads. For example, in a church or

an auditorium, aisles used for egress are defined by the placement of pews or

chairs. Occupants in an A‐3 subclassification are also usually alert and are often

more familiar with the space than in other assembly uses. Sample Building Types

Amusement arcades Armories Art galleries Assembly halls Auditoriums Bowling

lanes Churches and religious structures Community halls Courtrooms Dance halls

(not including food or drink consumption) Exhibition halls Fellowship halls

Funeral homes Galleries Gymnasiums (without spectator seating) Lecture halls

(may also be Business) Libraries Mortuary chapels Museums Passenger stations,

terminals, or depots (waiting areas) Pool and billiard rooms Public assembly halls

Recreation halls and piers Tents for assembly A‐4 This type is for the viewing of

indoor sporting events and other activities with spectator seating. The spectator

seating can consist of a defined area for seating or fixed seats such as bleachers.

Although A‐3 and A‐4 can have similar activities, if a defined area for viewing the

activities is provided, then it is an A‐4. For example, an indoor pool can be

classified as an A‐3 Assembly, but if the pool area also includes seating for

viewing swim competitions, it is considered an A‐4. (Similar activities can also

occur in A‐4 and A‐5 Assemblies.) Sample Building Types Arenas Gymnasiums

Indoor skating rinks Indoor swimming pools Indoor tennis courts A‐5 This type is

for the participation in or viewing of outdoor activities. This subclassification is

similar to A‐4, except that it is outdoors or in a structure with no roof. Sample

Building Types Amusement park structures Bleachers Grandstands Stadiums Note

A good rule of thumb is that when the occupant load is 50 or more, the

requirements for an Assembly occupancy should be researched. Typically in

Assembly occupancies, there are a large number of occupants. Examples include a

theater or large restaurant. However, when a space is used for a small group of

people to gather—such as a college classroom, an office conference room, or a

small restaurant—the codes often allow these uses to be classified under another

occupancy type. The IBC and the NFPA codes use an occupancy of 50 people or

more as the cutoff point. (Some jurisdictions may use a different limit.) For

example, if the IBC is used, a small restaurant can be classified as a Business

occupancy if its occupant load is less than 50. The NFPA codes would reclassify

this as a Mercantile occupancy. In many cases, the codes also allow an assembly‐

type use that is part of another occupancy classification to be considered the same

occupancy that it serves. It may depend on the size or the occupant load. For

example, the IBC allows rooms used for assembly purposes that are less than 750

square feet (70 square meters [sm]) or have an occupancy less than 50 to be

classified either as a Business occupancy or as part of the main occupancy

classification. Assembly occupancies that are related to Educational or are

accessory to a religious educational facility can also be classified with the

occupancy that they serve, according to the IBC. These clarifications can have

critical impact on the various code requirements that will apply. Business (B)

Occupancy Note A wide variety of building types can fall under the Business

occupancy classification. For example, a small Assembly, such as a restaurant that

has an occupant load fewer than 50 people, as well as college classrooms and

outpatient clinics, can be classified as a Business occupancy. A building or part of

a building is classified as a Business occupancy if it is used for the transaction of

business such as office, professional, or service‐type trades and other similar

functions. Limited areas that are a natural part of a business setting, such as small

storage, recordkeeping, supply areas, and break rooms, are included as well. The

risk factors in a Business occupancy are considered to be relatively low. This is

because there is typically a low concentration of occupants, and they are usually

alert and generally familiar with their environment. It is considered one of the

lowest‐risk occupancies. This classification can become very broad. For example, a

smaller Assembly‐like occupancy that has fewer occupants can sometimes be

classified as a Business occupancy, such as a small restaurant. Conversely, when

the function or size of any of the Business building types expands beyond a typical

business, the occupancy must be reexamined. Examples might include city halls

that include assembly areas or college facilities that include an auditorium

classroom. These areas may be classified separately as an Assembly occupancy or

a mixed occupancy. (See the section “Mixed Occupancies” later in this chapter.) In

addition, for an occupancy that offers health care services similar to a doctor's

office, but where procedures are performed that cause four or more patients to be

under sedation or conditions that would prevent them from being able to exit the

facility without assistance, the facility may have to be classified as an ambulatory

care facility. Under the IBC, this type of use is still considered a Business

occupancy, but will have specific code requirements that differ from those for a

typical Business occupancy. The NFPA codes have a separate occupancy

classification of Ambulatory Health Care. However, in both cases additional

requirements will apply. Educational‐type occupancies can also be confusing.

Colleges and universities (educational facilities after the twelfth grade) are

considered Business occupancies. Yet, business and vocational schools are often

considered as the same occupancy as the trade or vocation that is being taught. For

instance, general classrooms for a college would be classified as Business, but the

areas for instruction in automotive repair may be considered Factory/Industrial. In

addition, places that offer various types of training or skill‐development classes

can be classified as Business instead of Educational, regardless of the age of the

participants. Examples include places that offer music, dance, or tutoring. Sample

Building Types Airport traffic control towers Ambulatory care facilities Animal

hospitals, kennels, and pounds (part of the building could be considered Storage)

Automobile and other motor vehicle showrooms Automobile service stations (can

also be classified as Hazardous) Banks Barber shops Beauty shops Car washes

City halls Civic administration buildings Clinics (outpatient) College and

university classrooms Dentist's offices Doctor's offices Dry‐cleaning facilities (can

also be classified as Hazardous) Educational facilities (above twelfth grade)

Electronic data processing facilities Fire stations Florists and nurseries

Government offices Greenhouses Laboratories (nonhazardous) Laboratories

(testing and research) Laundromats Libraries (can also be classified as Assembly

or Business) Medical offices (separate from Institutional occupancies) Motor

vehicle showrooms Office buildings Outpatient clinics, ambulatory Police stations

Post offices Print shops Professional offices (architect, attorney, dentist, physician,

etc.) Radio and television stations (without audiences) Repair garages (small,

nonhazardous) Telecommunication equipment buildings Telephone exchanges

Travel agencies Educational (E) Occupancy A building or part of a building is

classified as an Educational occupancy if it is used for educational purposes by a

specified number of persons at any one time through the twelfth grade. Depending

on the code publication, the specified number of persons range from six to the

minimum number of people required for an Assembly occupancy. (For colleges

and universities, see Assembly and Business occupancies.) The NFPA codes also

specify a minimum amount of time that a space is used for educational purposes.

For example, if there are fewer than 12 hours of instruction per week, the building

type could be governed by a different occupancy classification, according to the

LSC. Note Although it may seem normal for college and university classrooms to

fall under the Educational occupancy, these building types are typically classified

as Business. However, they may also have spaces that are considered Assembly. It

is common for a typical school to have spaces that might be considered a different

occupancy, such as auditoriums, cafeterias, and gymnasiums. As of the 2012 IBC,

in most cases, these additional uses are not required to be classified separately

under an Assembly occupancy, but are allowed to be considered Educational as

well. Vocational shops, laboratories, and similar areas within a school will usually

be considered Educational, even though they may require additional fire

protection. As mentioned in a previous section, if the entire school is considered

vocational, some codes may require that it fall into the same classification as the

trade or vocation being taught. If an Educational occupancy also provides care and

sleeping accommodations, it could be classified as an Institutional occupancy or a

mixed occupancy. For example, the sleeping area of a boarding school or an

extended‐stay rehabilitation program may be classified as Residential. Day care

centers can also be classified as Institutional, depending on the number of children

and their age. Verify the proper designation with the local code official when

necessary. Sample Building Types Academies Day care centers (can also be

considered Institutional) Elementary schools High schools Junior high schools

Kindergartens Nursery schools Preschools Secondary schools Note Areas

providing day care during religious functions are allowed to be considered part of

the primary occupancy; this will affect many code requirements. Factory (F)

Occupancy A building or part of a building is designated as a Factory or Industrial

occupancy if it is used for assembling, disassembling, fabricating, finishing,

manufacturing, packaging, processing, or repairing. This designation generally

refers to a building in which a certain type of product is made. The product that is

made or the materials used to make the product must typically be considered a low

or moderate hazard. If it is a more hazardous material or product, the building or

space where it is made may be considered a Hazardous occupancy. The sample

product types listed here are typically considered low to moderate types of hazards

by the building codes. However, each code groups them a little differently under

the Factory/Industrial occupancy, and there may be different code requirements,

depending on which hazardous group the product is in. For example, the IBC

divides its Factory occupancy into F‐1 and F‐2. The NFPA uses the term Industrial

occupancy and has three subclassifications of that category. (See Figure 3.2. Also

see the section “Hazardous Occupancy” later in this chapter.) These

subclassifications are made for the different levels of hazardous materials or

activities that are part of the manufacturing process. Refer to the specific code to

determine if a manufactured product is considered moderate or low hazard; if more

hazardous materials are used or created in the space or building, it may have to be

classified as a Hazardous occupancy. Sample Building Types Assembly plants

Factories Manufacturing plants Mills Processing plants Low and Moderate

Hazardous Products Aircrafts Appliances Athletic equipment Automobiles and

other motor vehicles Bakeries Beverages (alcoholic) Beverages (nonalcoholic)

Bicycles Boats (building) Boiler works Brick and masonry Brooms or brushes

Business machines Cameras and photo equipment Canneries Canvas or similar

fabrics Carpets and rugs (includes cleaning) Ceramic products Clothing Condensed

powdered milk manufacturing Construction and agricultural machinery Creameries

Disinfectants Dry cleaning and dyeing Electric light plants and power houses

Electrolytic reducing works Electronics Engines (includes rebuilding) Film

(photographic) Food processing and commercial kitchens (not associated with a

restaurant, cafeteria, or similar dining facility) Foundries Furniture Glass products

Gypsum products Hemp products Ice Jute products Laboratories (can also be

classified as Business) Laundries Leather products Machinery Metal products

(fabrication and assembly) Millwork (sash and door) Motion pictures and

television filming Musical instruments Optical goods Paper mills or products

Plastic products Printing or publishing Recreational vehicles Refineries Refuse

incineration Sawmills Shoes Smokehouses Soaps and detergents Sugar refineries

Textiles Tobacco Trailers Upholstering Water pumping plants Wood (distillation

of) Woodworking (cabinetry) Hazardous (H) Occupancy A building or part of a

building that involves the generation, manufacturing, processing, storage, or other

use of hazardous materials is typically classified as a Hazardous occupancy. These

materials can include flammable dust, fibers or liquids, combustible liquids,

poisonous gases, explosive agents, corrosive liquids, oxidizing materials,

radioactive materials, and carcinogens, among others. In general, this classification

is categorized by an unusually high degree of explosive, fire, physical, and/or

health hazards. Note The NFPA codes do not have a separate Hazardous

occupancy. Instead, it is a subclassification under the Industrial occupancy and

addresses hazardous uses in each occupancy type. Hazardous building types

require additional precautions. Each code sets different standards and has special

sections dedicated to hazardous uses, which list very specific materials. In most

cases, a Hazardous occupancy can be subclassified as a low, medium, or high

hazard. Each building code categorizes the hazards a little differently. Often the

lower hazards are made part of the Factory/Industrial or Storage occupancy

classification. Each code also has a different number of subclassifications. The IBC

has five Hazardous classifications (H‐1 through H‐5). The NFPA codes, however,

include high hazard building types as a subclassification under Industrial. (See

Figure 3.2.) They do not have a separate Hazardous occupancy. When using the

NFPA codes, be careful to identify how that specific code or standard defines the

term hazardous, as they may vary slightly per code publication and the purpose of

the regulation. For example, in the LSC, the term hazardous is used to describe the

level of hazardous content of the space, whereas in the NFPA 13, Installation of

Sprinkler Systems, the term is used to define the ability of the sprinkler system to

control the fire. Note Sometimes two different buildings with the same building

type may have different occupancy classifications if hazardous materials are

present in one but not the other. For example, some auto repair shops are

considered a Hazardous occupancy. Others are considered a Business occupancy.

An important factor to consider is the amount of hazardous materials. If the

amount is small enough, the space or building may not be considered Hazardous

by the codes. A common example is a chemistry lab in a high school. As more

performance‐type requirements are introduced into code publications, more

emphasis will be placed on the types of products or materials used in a space rather

than on the type of building. If a space or building may contain hazardous

materials or conditions, consult the specific codes and work closely with the local

code officials. Some buildings may require only part of the building to be

classified as Hazardous. (Hazardous buildings and materials are beyond the scope

of this book.) Sample Building Types Airport hangars or airport repair hangars

Dry‐cleaning plants Explosives manufacturers Film storage, combustible

Firearm/ammunition warehouses Gas plants Laboratories with hazardous

chemicals Paint and solvent manufacturers Paint shops and spray painting rooms

Pesticide warehouses Power plants Pumping/service stations Tank farms

Warehouses with hazardous materials Institutional (I) Occupancy A building or

part of a building is classified as an Institutional occupancy if it includes care or

supervision of the occupants, including medical care. The primary distinction of

this classification is that the occupants are either limited in their mobility,

immobile, or incapable of mobility due to physical or security restraints. In most

cases, the occupants must depend on others to help them evacuate the building in

case of an emergency. The IBC has four Institutional subclassifications (I‐I

through I‐4). The NFPA, on the other hand, separates these uses into different

occupancy classifications. The NFPA codes refer to them as

Detentional/Correctional, Health Care, and Day Care occupancies. (See Figure

3.2.) Using the IBC designations, each subclassification is described in the

following subsections; the similar NFPA classification is given as well. Note,

however, that the specific definition for each NFPA occupancy may vary from

those in the IBC. The minimum and maximum number of occupants can vary as

well. For example, the minimum number for an I‐4 classification in the IBC is 6

and the minimum number for a Day Care occupancy in the LSC is 4. Refer to the

applicable code to determine the correct occupancy classification. (Also see the

inset titled “Rooms and Spaces” later in this chapter.) Note The IBC has four

Institutional subclassifications. The NFPA codes divide these into separate Health

Care, Detentional/Correctional, and Day Care occupancies. Because some uses can

be determined by subtle differences, a discussion with a code official may be

required to confirm whether the jurisdiction will consider the facility Institutional,

Residential, or one of the other specific NFPA classifications. The applicable code

requirements can vary significantly between these occupancies. Note Custodial

care describes when assistance with day‐to‐day living tasks is given but the

occupant can evacuate independently at a slow rate. Depending on additional

factors, these occupancies can be Institutional or Residential. I‐1 This type is for

the housing and custodial care of a certain number of occupants on a 24‐hour basis.

The codes often use 16 occupants as the limit. (This number does not include

staff.) These occupants, because of age or mental disability, require supervision.

However, they can typically respond to an emergency without physical assistance

from staff. If fewer than 16 people with the same characteristics were being cared

for, the occupancy would be reclassified as Residential. The NFPA considers this

building type a Residential occupancy (Board and Care), which includes a section

for larger and smaller types of facilities. Sample Building Types Alcohol and drug

centers Assisted living facilities (can also be classified as Residential) Congregate

care facilities (16 or fewer occupants) Convalescent facilities Group homes

Halfway houses Residential board and custodial care facilities Social rehabilitation

facilities I‐2 This type is for medical, surgical, psychiatric, nursing, or other type of

care on a 24‐hour basis for more than five persons. These occupants are not

capable of self‐preservation. If fewer than five people are being cared for, the

occupancy would typically be reclassified as Residential. The similar NFPA

category is under a separate occupancy classification called Health Care. Sample

Building Types Day care centers (24‐hour) Detoxification facilities Foster care

Hospitals Infirmaries Limited care facilities Mental hospitals Nursing homes

(intermediate care and skilled nursing) Psychiatric hospitals Treatment or

rehabilitation centers I‐3 This type is for the detention of more than five persons.

These occupants are incapable of self‐preservation due to security measures.

Additional “conditions” based on the level of security provided and the amount of

free movement allowed within the building must be considered to accurately

determine the specific code requirements for this use. (This topic is beyond the

scope of this book.) The similar NFPA category is the Detention/Correction

occupancy classification, which is divided into five separate subclassifications (see

Figure 3.2), depending on the level of security. The LSC has special conditions for

lock‐up areas in facilities other than Detentional/Correctional. These areas are

similar to those in typical I‐3 facilities, as the occupants are incapable of self‐

preservation due to security measures. However, only one person has to be held in

this condition for these requirements to apply. A lock‐up area is most typically

located in facilities such as immigration centers at border crossings; customs

facilities in international airports; prisoner holding at police departments; or

security areas at parks, sports stadia, and similar uses. Sample Building Types

Correctional institutions Detention centers Jails Prerelease centers Prisons

Reformatories Work camps I‐4 This type is for the care of more than five persons

for less than 24 hours a day. This includes adults and children under 2 years of age.

One typical exception is that if adults in this type of facility are capable of self‐

preservation without help from staff, it would be reclassified as an R‐3. (See

Residential occupancy R‐3.) Another is when the area where children are cared for

opens directly to the exterior; it can then be reclassified as Educational. This is

considered a Day Care occupancy in the NFPA codes. Sample Building Types

Adult day cares Day care centers—caring for infants (can also be classified as

Educational) Mercantile (M) Occupancy Note According to the NFPA codes, a

small use that would normally be classified as a type of Assembly occupancy, such

as a small diner, can sometimes be classified as Mercantile. (In the IBC, this may

be reclassified as Business.) A building or part of a building is classified as a

Mercantile occupancy if it is open to the public and used for the display, sale, or

rental of merchandise. This classification includes most stores and showrooms, and

in some codes includes large malls. The IBC groups these into one main

occupancy. Mercantile in the NFPA codes has three subclassifications based on the

type and size of the building. (See Figure 3.2.) A group of retail stores may have

additional code requirements. Each store would be considered a separate

Mercantile occupancy. However, as a group, the stores may also be considered a

covered mall. The codes have special requirements for malls because, in addition

to the large anchor retail stores and the multiple smaller retail tenants, there can be

other uses within the same building. Most typically, these include restaurants and

entertainment areas. In some cases, the general Mercantile requirements apply; in

other cases, the requirements for a covered mall may apply to the project. (Usually

one or the other will be used.) These mall requirements can be found in the

“special occupancy” chapter of the IBC. In the NFPA codes, special requirements

for malls are called out within the Mercantile chapter. When necessary, review

these requirements with the local code official. Sample Building Types Auction

rooms Automotive service stations Bakeries Department stores Drug stores

Grocery stores Markets Paint stores (without bulk handling) Rental stores Retail

stores Salesrooms Shopping centers Showrooms Specialty stores Supermarkets

Wholesale stores (other than warehouses) Residential (R) Occupancy A building or

part of a building that acts as a dwelling and provides sleeping accommodations for

normal residential purposes is designated a Residential occupancy. Most of the

codes further categorize this classification based on the probable number of

occupants and how familiar they are with their surroundings. For example, a

person in a hotel would probably not be familiar with the escape routes, making it

more hazardous. Such an occupancy will be subject to stricter codes than an

apartment complex, where tenants should be more familiar with their surroundings.

In some cases, the number of units in the building may also make a difference. (For

other occupancies that provide sleeping accommodations but with additional care,

see Institutional occupancy.) Note Certain Residential building types may have to

be reclassified as Institutional, depending on the number of occupants and their

length of stay. Examples include day care centers and nursing homes. The IBC has

four Residential subclassifications: R‐1 through R‐4. The NFPA codes separate

these into five separate classifications: Apartment Buildings, Hotels and

Dormitories, Lodging or Rooming Houses, One‐ and Two‐Family Dwellings, and

Board and Care. (See Figure 3.2.) Although these categories are similar to those in

the IBC, there are differences. Refer to the applicable code to determine the correct

occupancy or subclassification. (Also see the inset titled “Rooms and Spaces” later

in this chapter.) Note The term dwelling unit is often associated with Residential

and Institutional occupancies. (See the inset titled “Rooms and Spaces” in this

chapter for more information.) R‐1 This type is for occupants who are transient—

in other words, those who do not stay for an extended period of time. If occupants

typically stay more than 30 days, a building type may be required to be reclassified

as R‐2 or another use. In the NFPA codes, transient residential building types are

addressed separately as hotels in the Hotels and Dormitories subclassification or

the Lodging or Rooming Houses subclassification. Sample Building Types

Boarding houses (transient with more than 10 occupants) Congregate living

facilities (transient with more than 10 occupants) Hotels Inns Lodging and rooming

houses Motels Rooming houses Note Congregate living facilities are most often

classified as an R‐2. This building type contains sleeping units but shared

bathroom and/or kitchen facilities (e.g., a small boarding house). If it is a large

facility, it may be classified as R‐1 or I‐2. R‐2 This type is for buildings that

contain more than two dwelling units with occupants who are somewhat permanent

(less transient). The similar NFPA categories include Apartment Buildings,

Lodging or Rooming Houses, and Hotels and Dormitories. CUSTODIAL CARE

VERSUS MEDICAL CARE Determining the correct occupancy classification

when care is being provided for occupants often is determined by the number of

persons receiving care. However, in some cases the type or level of care should be

considered. The codes specify two basic types of care: custodial and medical.

Custodial care includes assistance with typical daily tasks such as cooking, taking

medications, bathing, and other personal care. This level of care assumes that the

person receiving care is capable of responding to an emergency situation but

potentially at a slower rate. Their conditions may include physical or mental

impairments. Medical care includes care or treatment involving medical or surgical

procedures, nursing care, or psychiatric care. These occupants are often considered

not to be able to respond in the event of an emergency because of their current

physical or mental condition. Residential occupancies often assume that only

custodial care is being provided. Institutional occupancies and ambulatory care

facilities assume that some level of medical care is being provided. Sample

Building Types Apartments Boarding houses (nontransient with more than 16

occupants) Congregate care facilities (nontransient with more than 16 occupants)

Convents Dormitories Fraternities/sororities Hotels (nontransient) Live/work units

Monasteries Motels (nontransient) Multiple single‐family dwellings Vacation

timeshare properties R‐3 This type is for more permanent residences but, unlike R‐

2, is most often used for single or duplex units. The typical single‐family home

falls into this category. Some residential care facilities (see R‐4) may also be

allowed under this classification if the number of occupants is limited to less than

10 or the length of stay is less than 24 hours. Congregate living facilities for 16

persons or fewer are typically included in this subclassification as well. If the I‐

Codes are used, a jurisdiction will typically require the use of the International

Residential Code (IRC) for the specific code requirements for single and duplex

residences. Each NFPA code references its chapter on one‐ and two‐family

dwellings as well. (See Appendix C for more information on family residences.)

Verify with the local code official which code is applicable to residential projects.

Note The accessibility chapter of the IBC requires that the work area and the

residential area of a live/work unit be evaluated separately. Sample Building Types

Facilities that do not contain more than two dwelling usages Boarding houses

(nontransient with 16 or fewer occupants) Boarding houses (transient) with 10 or

fewer occupants Care facilities (5 or fewer persons receiving care) Congregate

living facilities (nontransient with 16 or fewer occupants) Congregate living

facilities (transient with 10 or fewer occupants) Note Single‐family homes and

duplex units are classified as an R‐3 occupancy by the IBC and typically require

use of the International Residential Code (IRC). The NFPA designation is One‐

and Two‐Family Dwellings. (Refer to Appendix C.) R‐4 This type is for small to

medium‐sized residential care facilities. This occupancy is based on the number of

persons receiving custodial care on a 24‐hour basis and does not include staff. The

typical number of residents is between 6 and 16. If fewer people are receiving care,

it may be considered an R‐3. If a larger number of people are receiving care or if

medical care is also being provided, then it may be considered Institutional. These

occupants are capable of self‐preservation. (See I‐1.) The similar NFPA category

would be Residential Board and Care. It could also be considered a Health Care

occupancy by the NFPA, depending on the number of occupants. If these types of

facilities are protected by an automatic sprinkler system, they may be able to

follow the requirements of the IRC instead of the IBC. Sample Building Types

Alcohol and drug abuse centers Assisted living facilities (can also be classified as

Institutional) Convalescent facilities (can also be classified as Institutional) Group

homes Halfway houses Retirement homes Residential board and care facilities

Social rehabilitation facilities Storage (S) Occupancy A building or a predominant

part of a building is classified as a Storage occupancy if it is used for storing or

sheltering products, merchandise, vehicles, or animals. Minor storage uses, such as

smaller storage rooms and supply closets, are typically treated as part of the

predominant occupancy. As with Factory/Industrial occupancies, low‐ or

moderate‐hazard contents are typically allowed in the Storage occupancy, although

the storage of high‐hazard contents may cause the building or space to be classified

as Hazardous. The classification depends on the type of hazard and the quantity of

material being stored. It can also be affected by how the products are stored, i.e.,

on pallets or in containers. It is important to check the code to determine the level

of hazard of the material being stored. A list of low‐ and moderate‐hazard items

follows, but remember that each code groups them differently and each level will

have slightly different requirements. The IBC has two storage subclassifications,

one for moderate hazards (S‐1) and another for low hazards (S‐2). The NFPA has

only one main storage classification. If unsure about the types of hazardous

materials being stored, check with the local code official. In addition, within

Storage building types, it is generally understood that relatively few people will

occupy the space. If the number of occupants is large or increases substantially in

the future, the building occupancy may have to be reclassified. Sample Building

Types Aircraft hangars (nonhazardous) Cold storage facilities Creameries Freight

terminals and depots Grain elevators Repair garages (nonhazardous) Truck and

marine terminals Warehouses (nonhazardous) Asbestos Beer or wine up to 12

percent alcohol in metal, glass, or ceramic containers Cement in bags Chalk and

crayons Cold storage Dairy products in non‐wax‐coated paper containers Dry cell

batteries Dry insecticides Electrical coils Electrical insulation Electrical motors

Empty cans Food products Foods in noncombustible containers Fresh fruits and

vegetables in nonplastic trays or containers Frozen foods Glass Glass bottles,

empty or filled with noncombustible liquids Gypsum board Inert pigments Ivory

Meats Metal cabinets Metal desks with plastic tops and trim Metal parts Metals

Mirrors New empty cans Oil‐filled and other types of distribution transformers

Open parking structures Porcelain and pottery Stoves Talc and soapstone Sample

low‐ and moderate‐hazard storage contents Washers and dryers Utility (U)

Occupancy A building or part of a building that is not typical and/or cannot be

properly classified as any of the other occupancy groups is often classified as a

Utility, Special, or Miscellaneous occupancy. The building codes and LSC list

different items in this category, and they are usually covered as a group in a

separate chapter or in multiple chapters within each of the codes. If unsure whether

a building would be considered a Utility or Miscellaneous occupancy, check with

the local code official in the early stages of a project. (Unusual structures are

beyond the scope of this book.) Note The IBC also includes requirements for

children's playground structures. This applies to play areas inside any occupancy if

it is a certain size. The requirements address size, materials, fire protection, and

separation from other elements. Sample Building Types Agricultural buildings

(including barns, stables, livestock shelters) Carports Grain silos Greenhouses

Livestock shelters including stables Open structures Parking garages (can also be

classified as Storage) Private garages Retaining walls Sheds Tall fences (over 6

feet, or 1829 mm) Tanks Temporary structures Towers If one of the typical

occupancies is being housed in an unusual structure, additional codes are usually

required. Examples include high‐rise, underground, and windowless buildings.

And, if special conditions are required in particular space or are a specific use,

such as Ambulatory Care facility, hyperbaric facilities, or storm shelters, additional

codes may be required. These will generally be assigned to one of the occupancies

discussed above, but they need special attention and further research because of the

additional code requirements they must meet. NEW VERSUS EXISTING

OCCUPANCIES Because a majority of code requirements are based on the

occupancy classification of the space or building, it is important to understand their

differences. For many projects, additional occupancy‐related issues must be

considered. In some cases, for example, different code requirements may apply

depending on whether the project is considered a renovation or a new construction.

Whether an occupancy is considered new or existing becomes especially important

when using the Life Safety Code because the LSC separates its regulations into

these two different categories for each occupancy classification. The new or

existing designation for these occupancies will affect how the codes must be

applied. An occupancy is considered new if it falls into one of the following

categories: The occupancy is in a building or space constructed for that occupancy

under the currently enforced code edition. The occupancy is relocated to an

existing building previously not used for that occupancy. The occupancy is in a

new addition to an existing building previously not used for that occupancy. The

occupancy is remaining in the same building but changing its size or use that

affects its subclassification. This last category is important to remember because it

is the least obvious. In some cases a change in size or use will cause the occupancy

classification to be considered new. However, in other cases, if the change does not

result in an increase in hazards or risk factors, the code official may allow it to

change subclassification but still be considered existing. A change in occupancy

classification can affect a number of other code regulations, including those found

in the building codes, the International Existing Building Code (IEBC), and the

LSC. (See Appendix B for more information on changes in occupancies in existing

buildings.) If the occupancy is considered new, then many changes may be

required to the entire space. If the occupancy is considered existing, then many of

the existing conditions may be allowed to remain the same. ROOMS AND

SPACES Each building or space must be assigned an occupancy classification so

that it can be determined which codes apply. In addition, certain rooms within an

occupancy can have specific requirements. This is especially true in Residential

and Institutional occupancies. The codes have very distinct definitions for various

types of spaces, depending on how those spaces are utilized. The following are

commonly referenced in the codes: Occupiable space. A room or enclosed space

designed for human occupancy that is equipped with means of egress, light, and

ventilation, as required by the codes. This can include the spaces and rooms in

most occupancies. It excludes such areas as mechanical and electrical rooms, crawl

spaces, and attics. If a space is not considered occupiable, it usually does not have

to meet typical accessibility requirements as specified in the building codes, the

ICC standard, or the ADA. Dwelling unit. A single unit providing complete

independent living facilities for one or more persons, including permanent

provisions for living, sleeping, eating, cooking, and sanitation. Building types that

fall into this category include single‐family homes, apartment units, townhouses,

and certain assisted living units. However, a hotel guest room or dorm room can

also be considered a dwelling unit if it has a kitchenette, eating area (i.e., table or

bar top), and living area (i.e., upholstered seating area) in addition to the typical

sleeping area and bathroom. (The ICC standard and the IBC divide dwelling units

into Type A and Type B types for accessibility reasons. Type B dwellings have

requirements similar to those of the FHA Accessibility Guidelines (FHAG). Type

A dwellings have additional requirements for accessibility.) Live/Work unit. A

dwelling unit or sleeping unit where a significant portion (greater than 10 percent,

but less than 50 percent) is used for nonresidential use by the tenant. It has a

maximum area of 3000 square feet (279 sm) and must be located on the main floor

of the unit. (A typical home office would not be considered a live/work unit.)

Sleeping unit. A sleeping unit or room is used primarily for sleeping and does not

fit the definition of a dwelling unit. The space often includes a bathroom, but it

would not include a cooking area (or it could include a kitchen area but no

bathroom). Examples include typical guest rooms in hotels and boarding houses,

jail cells, dorm rooms, and patient rooms in nursing homes or hospitals. Guest

room or suite. A guest room (or suite) is for living or sleeping in and may include

sanitation and storage facilities within a compartment or a contiguous group of

rooms. Examples include rooms and/or suites in hotels, motels, and dormitories.

Care suite. A special grouping of treatment rooms or sleeping rooms and their

support rooms and the circulation space to the rooms. The arrangement usually

occurs in Institutional or Health Care occupancies and typically must be under

direct supervision by staff. Examples include an emergency suite or a critical care

suite in a hospital. Living area or room. This is considered any occupiable space in

a Residential occupancy, other than sleeping rooms or rooms that are intended for

a combination of sleeping and living. It includes spaces such as bathrooms (or

toilet compartments), kitchens, closets, halls, and storage/utility spaces, but can

also include other rooms such as living rooms, dining rooms, family rooms, and

dens. Habitable room. A room in a Residential occupancy that is used for living,

sleeping, cooking, and eating, but excludes such things as bathrooms,

storage/utility spaces, and hallways. The designation of new and existing

occupancies in the LSC and other NFPA documents allows the code official to

require existing facilities, not just new occupancies, to maintain safe environments

for their occupants even if the use does not change. Under the typical building

code, including the IBC, new code requirements do not become retroactively

applicable to an existing occupancy. Only when the space is renovated or a major

addition is made can existing space be required to meet the newer codes. Note

When using the LSC, it makes a difference if the project is considered new or

existing. The IEBC may be required instead of the IBC in some jurisdictions.

Remember, a change in occupancy classification or subclassification can be subtle,

yet it can change the requirements for the space. For example, if a restaurant

changes to a nightclub or a restaurant changes the seating arrangements so that

more people can occupy the space, both can result in a change of occupancy

classification. Even these slight modifications can change the sprinklering,

occupant load, exit requirements, and so forth. MORE THAN ONE

OCCUPANCY TYPE Two or more occupancies can occur in the same building. In

fact, it is actually more common to see several different occupancies in the same

building than to see a single‐occupancy building. A common example is a large

hotel. Many large hotels have restaurants, indoor pools, conference areas, and spas.

The hotel itself would be classified as Residential, but the restaurants, pools, and

conference areas would be considered Assembly occupancies, and the spa would

be classified as a Business occupancy. Note When more than one occupancy

exists in the same building or space, it will be considered an accessory, mixed, or

multiple occupancy. A variety of examples are listed here so that different building

types can be analyzed and differences between various uses can be distinguished.

(There are many other possibilities.) Notice how often the Assembly and Business

occupancies occur together. These are common occupancies in mixed building

types. Hotels (Residential) with restaurants, ballrooms, or workout rooms

(Assembly or Business) Elementary, middle, and high schools (Educational) with

gymnasiums, auditoriums, and cafeterias (Assembly) Office buildings (Business)

with day care centers (Educational or Institutional) Hospitals (Institutional) with

cafeterias (Assembly) Reformatories (Institutional) with recreational rooms

(Assembly) and offices (Business) Factories (Industrial) combined with the office

headquarters (Business) Malls (Mercantile) with small restaurants (Business) or

large food courts (Assembly) It is important to determine if more than one

occupancy is occurring in the same building. If so, it can affect a number of other

codes, such as those listed in Figure 3.1. These different occupancies can be

adjacent horizontally, as in the Plan in Figure 3.3, or vertically in the case of a

multi‐story building, as shown in the Section in Figure 3.3. Because each

occupancy type has different safety risks, special measures are necessary to make

the building safe. In general, the codes require that either the occupancies be

separated or all of them be treated as one, using the most stringent requirements.

The codes describe the relationship of more than one occupancy differently. The

International Building Code refers to the relationship as accessory, separated

mixed, or nonseparated mixed. In a similar way, the NFPA codes, including the

Life Safety Code, define different occupancies as either accessory, mixed multiple,

or separated multiple occupancies. The requirements for each type of “mixed”

occupancy are described in the next sections. For all of these, the ultimate goal is

to provide the safest building possible. Figure 3.3 Mixed occupancies: Horizontally

and vertically (1 square foot = 0.0929 square meter). Incidental Use Certain uses

within a building are determined to be more hazardous when they occur in any

occupancy type. Previously referred to as incidental use areas and incidental

accessory occupancies in the IBC, they are now referred to as incidental uses. They

are referred to simply as hazardous areas in the NFPA codes. However, in both sets

of codes, if their size is limited, they are not considered a separate occupancy. For

example, the laundry room within the preschool facility (Educational) shown in

Plan A of Figure 3.4 would be considered an incidental use within the other

primary‐use areas such as classrooms and office areas. Figure 3.4 Incidental use

versus accessory occupancy (1 square foot = 0.0929 square meter). The types of

spaces and rooms that are considered incidental use are indicated within the codes

either in a table (IBC) or in the text (NFPA). These spaces include boiler rooms,

furnace rooms, large laundry rooms, and other spaces containing hazardous items

or machinery. The size of the use is limited by the codes. In the IBC, the use

cannot exceed 10 percent of the building area of the floor on which it is located. In

addition, both the IBC and the NFPA codes provide minimum areas for when the

use will be considered an incidental use. For example, the IBC lists specific

incidental uses in a table, as shown in Chapter 6 in Figure 6.8 . As indicated in this

table, additional fire and smoke protection is required for these areas. (This is

discussed further in Chapter 6.) When this additional protection is provided, all

other code requirements for the incidental accessory occupancies follow the codes

required for the main occupancy. If this protection is not provided, the building

must be classified as a mixed occupancy. (See the section “Mixed Occupancies”

later in this chapter.) The NFPA codes list these areas within the occupancy

chapter in which they are most likely to occur. For example, the requirement for

separation of soiled linen rooms can be found in the Health Care occupancy

chapter. Accessory Occupancies Sometimes two or more occupancies exist in a

building, but one or more of them is much smaller than the main occupancy type.

In this case, the smaller occupancy(ies) may be considered an accessory occupancy

by the codes. In the IBC, for instance, an area can be considered an accessory use

if the smaller occupancy classification(s) is less than 10 percent of the total area of

the floor on which it is located. (The NFPA codes may allow the accessory use to

be a larger percentage of the overall area.) So, using the IBC, an example would be

a furniture store that offers design services, as shown in Plan B of Figure 3.4. The

furniture store is Mercantile (M), but the design center area would be Business (B).

However, since the area of the design center is less than 10 percent of the overall

area, it can be considered an accessory to the main Mercantile occupancy. And,

because it can be considered an accessory use, the two areas will not have to be

designed under separate occupancy requirements. Sometimes there are several

smaller uses occurring within a larger occupancy classification, and all are located

in the same building. An example would be a large discount store, like the one

shown in Plan A of Figure 3.5. This particular store has a bakery, photo shop, hair

salon, and snack bar as part of its space. In this case, all the accessory spaces

combined cannot be more than the allowable percentage of the total area. Figure

3.5 Accessory versus occupancy examples (1 square foot = 0.0929 square meter).

Note The NFPA codes allow an accessory occupancy to be a larger percentage of

the overall space or building than does the IBC. In addition to the proportionality

requirement, an accessory occupancy cannot exceed the allowable area for that

occupancy classification in relation to the construction type of the building. For

example, Plan B in Figure 3.5 is an electronics store (Mercantile, or M) with its

warehouse located in the same building. The warehouse is considered a Storage (S‐

1) occupancy. It could be considered an accessory occupancy by the IBC because

it does not exceed 10 percent of the total area of the building. However, because

the area of the S‐1 occupancy exceeds the allowable area for this particular

construction type, the S‐1 occupancy cannot be considered an accessory to the

Mercantile. In this case, the storage area would be considered a separate storage

occupancy and would have to meet the code requirements for an S‐1 occupancy

classification instead of the requirements for a Mercantile occupancy. In some

cases, certain areas are allowed to be accessory regardless of the percentage of

area. For example, Assembly areas with an occupant load less than 50 and areas

with less than 750 square feet (69.7 sm) can be considered accessory to the main

occupancy—a small training room in an office space, for instance. However, in

both the IBC and the NFPA codes, some occupancies cannot be considered

incidental or accessory to any other classification. This includes Day Care

occupancies (except for religious uses) and certain types of Residential and

Educational building types. (Hazardous occupancies can never be considered as

accessory to another occupancy.) It is useful for design purposes to determine if an

area can be considered accessory to the main area, because it simplifies the code

requirements and allows areas to be more open. If the smaller occupancy(ies)

cannot be considered accessory, the space or building would have to be designed

as a separated or nonseparated mixed occupancy regardless of the size. (See the

next section.) When there are approved accessory occupancies within a space or

building, most of the code requirements (including the means of egress

requirements) are based on the main occupancies. The fire protection requirements,

however, are based on the most restrictive use (whether the accessory or main use)

and apply to the entire building or space. Mixed Occupancies When two or more

occupancies in a building or space are about the same size or do not meet the

requirements to be considered an accessory use, it is a mixed occupancy. To

address the specific situation, the IBC further divides mixed occupancies into

separated mixed occupancies and nonseparated mixed occupancies. (The NFPA

codes also use the term separated but only in relation to multiple occupancies. This

is explained later in this chapter.) When the different occupancies are divided by

the required rated assemblies (e.g., walls, floor, and/or ceiling assemblies), these

occupancies are considered by the IBC to be separated mixed occupancies. (The

requirements for rated assemblies are discussed further in Chapter 5.) Once

separated, each occupancy only needs to meet the requirements of its own

occupancy classification. For example, in Plan A in Figure 3.6, the Business (B)

occupancy and the Mercantile (M) occupancy are separated by a rated wall. Thus,

the code requirements for the Business occupancy would apply to the post office

and the Mercantile requirements would apply to the shoe store. Figure 3.6 Mixed

occupancies in the IBC: Separated and nonseparated (1 square foot = 0.0929

square meter). When there is no rated separation between the occupancies, it is

considered by the IBC as a nonseparated mixed occupancy. (This term is not used

by NFPA.) When the occupancies are considered nonseparated, both of the

occupancies must then meet the requirements of the most stringent occupancy

classification, including construction type, allowable area, finishes, fire protection,

and exiting requirements. For example, in Plan B of Figure 3.6, the Mercantile (M)

and Assembly (A‐2) occupancies are separated by a partition only for visual

reasons and so are considered nonseparated. In this case, the more stringent

Assembly requirements for the restaurant would be applied to the entire area of the

building, including the gift shop. In buildings where there are both separated and

nonseparated mixed occupancies,

Kennon, Katherine E.; Harmon, Sharon K.. The Codes Guidebook for Interiors

(pp. 136-184). Wiley. Kindle Edition.

not meet the requirements to be considered an accessory use, it is a mixed

occupancy. To address the specific situation, the IBC further divides mixed

occupancies into separated mixed occupancies and nonseparated mixed

occupancies. (The NFPA codes also use the term separated but only in relation to

multiple occupancies. This is explained later in this chapter.) When the different

occupancies are divided by the required rated assemblies (e.g., walls, floor, and/or

ceiling assemblies), these occupancies are considered by the IBC to be separated

mixed occupancies. (The requirements for rated assemblies are discussed further in

Chapter 5.) Once separated, each occupancy only needs to meet the requirements

of its own occupancy classification. For example, in Plan A in Figure 3.6, the

Business (B) occupancy and the Mercantile (M) occupancy are separated by a

rated wall. Thus, the code requirements for the Business occupancy would apply to

the post office and the Mercantile requirements would apply to the shoe store.

Figure 3.6 Mixed occupancies in the IBC: Separated and nonseparated (1 square

foot = 0.0929 square meter). When there is no rated separation between the

occupancies, it is considered by the IBC as a nonseparated mixed occupancy. (This

term is not used by NFPA.) When the occupancies are considered nonseparated,

both of the occupancies must then meet the requirements of the most stringent

occupancy classification, including construction type, allowable area, finishes, fire

protection, and exiting requirements. For example, in Plan B of Figure 3.6, the

Mercantile (M) and Assembly (A‐2) occupancies are separated by a partition only

for visual reasons and so are considered nonseparated. In this case, the more

stringent Assembly requirements for the restaurant would be applied to the entire

area of the building, including the gift shop. In buildings where there are both

separated and nonseparated mixed occupancies, additional requirements apply. For

instance, the most stringent fire protection requirements will apply to the entire

building. Note Both the IBC and the NFPA codes use the term separated for when

two or more occupancies are divided by rated assemblies—called separated mixed

by the ICC and separated multiple by NFPA. Many factors influence the decision

to treat a mixed occupancy as separated or nonseparated. Constructing rated

assemblies for separation can be expensive or undesirable for the design, but

having to meet the most stringent exiting requirements, construction type, or area

limitations for the whole building or space may limit the design unnecessarily. All

these factors must be considered to determine the better choice for a project.

Multiple Occupancies Multiple occupancies is a term used by the NFPA codes (not

the I‐Codes). It occurs when two or more occupancies exist in a building or space

either horizontally or vertically. Multiple occupancies are designated more

specifically as mixed or separated. The NFPA codes consider a building or space

to be a mixed multiple occupancy when two or more occupancies exist together

and are “intermingled.” This can occur if (1) there is no rated separation(s)

between the occupancies, (2) the different occupancies use the same exiting

components (aisle, corridors, stairs, etc.), or (3) both conditions exist. For example,

refer again to Plan B in Figure 3.6; because there is no rated separation between

the Assembly (A‐2) and Mercantile (M) occupancies, it is considered a mixed

multiple occupancy. In addition, if a portion of the occupants from the restaurant

must exit through the gift store as part of the required exiting, that would also

make it a mixed occupancy. Note The term mixed multiple occupancy is unique to

the NFPA. Although similar to nonseparated mixed occupancies in the IBC, a

mixed multiple occupancy includes a wider variety of building scenarios. A

different type of mixed multiple occupancy is shown in Plan A of Figure 3.7.

These occupancies are separated by rated walls and may seem to be separated

occupancies. However, because the tenants share the corridor when exiting from

each space, it would be considered a mixed multiple occupancy by the NFPA

codes. If a multiple occupancy is considered mixed, the construction type, fire

protection, and means of egress, as well as other requirements, must follow the

most restrictive occupancy requirements. (In this way, it is similar to nonseparated

mixed occupancies in the IBC.) Figure 3.7 Multiple occupancies in the NFPA

codes: Mixed and separated. On the other hand, if the occupancies are separated by

rated walls but do not share exiting, then the NFPA considers the area a separated

multiple occupancy. Like the separated mixed occupancy in the IBC, each space

must only meet the code requirements for its occupancy classification. An example

of a separated multiple occupancy can be seen in Plan B of Figure 3.7. Here the

multiple occupancy classifications are separated from each other by a rated wall. In

addition, each has its own separate means of egress, so they do not share a

common corridor. All of these factors make it a separated multiple occupancy.

Note If they meet all the code requirements, incidental accessory use and accessory

occupancies will not make a building a mixed‐use occupancy. The NFPA codes

designate how a mixed or separated multiple occupancy should be handled. More

specific information on multiple occupancies may also be found within each

occupancy chapter. These requirements supersede the general requirements for

mixed or separated occupancy classifications. These individual occupancy chapters

must be reviewed to know when they apply. In addition, a code official may need

to be consulted to determine which requirements will apply to the different areas

versus the whole building. This is especially important if working in a jurisdiction

that requires both the IBC and the LSC. ACCESSIBILITY REQUIREMENTS

Under certain conditions, almost all occupancy classifications can be considered

public accommodations and/or commercial facilities and can be regulated by the

ADA Standards under the ADA. In addition to the general accessibility

requirements described throughout this book, the ADA Standards include specific

requirements for certain building types within various occupancies. The building

codes and the ICC A117.1 accessibility standard also include some similar

requirements, although these are not as extensive as those of the ADA Standards.

Note Both the 1991 ADA Standards and the 2010 ADA Standards include

regulations specific to certain occupancies. Refer to these requirements for details.

The following is a list of building types found in the ADA Standards and the

special accessibility requirements required for each. (The type of occupancy

classification is indicated as well.) This list is based on the 2010 ADA Standards.

In addition, there are specific storage requirements for any occupancy that requires

accessible storage as well as additional requirements specifically for dwelling units

(Residential). When working within these occupancies, the code research should

include reviewing the current ADA Standards as well as comparing them to the

ICC A117.1 standard, the accessibility chapter of the IBC, and other codes

enforced by the local jurisdiction to see if there are contradictory or stricter

requirements. Other federal accessibility regulations may also apply (e.g., FHAG

and ABA Standards), as explained in Chapter 1, and additional regulations for

certain occupancies may be added in the future. When necessary, consult the local

code official or the ADA Access Board for clarification. Assembly Areas

Percentage of accessible wheelchair locations Location and dispersion of

wheelchair spaces and companion seats Access to performance areas Types of

floor surfaces Assistive listening systems requirements Types and placement of

listening systems Businesses and Mercantile Size of checkout counters and work

surfaces Clearance and height of self‐service shelves/display units Size of teller

windows and information counters Width and quantity of checkout aisles Note

Many requirements of the 2010 ADA Standards are similar to those in the ICC

A117.1 and the accessibility chapter of the IBC. Clearance at security elements

Number, size, and types of dressing/fitting rooms Type and clearance of automatic

teller machines Medical and Long‐Term Care Facilities (Institutional and Health

Care) Size of covered entrances for unloading patients Percentage of accessible

toilets Percentage and dispersion of accessible patient bedrooms Dispersion of

accessible patient bedrooms Size of maneuvering spaces in patient rooms

Clearance area at patient beds Width of accessible doors and aisles Restaurants and

Cafeterias (Business or Assembly) Percentage of accessible fixed tables Access to

sunken and raised platforms Width of food service lines Height of counters and

self‐service shelves Access to controls of vending machines Width of access aisles

Transient Lodgings (Residential) Percentage of accessible sleeping rooms

Dispersion of accessible elements in types of rooms Specific requirements within

accessible rooms Number and dispersion of rooms for hearing‐impaired Dispersion

of accessible rooms suitable for disabled with multiple disabilities (mobility,

hearing, visual, etc.) Access to rooms and public and common areas Width of door

openings Size of maneuvering spaces Percentage of accessible amenities (ice

machines, washers and dryers, etc.) Clearance, height, and hardware of storage

units Housing at Places of Education (similar to Transient Lodging and

Residential) Percentage of accessible units Dispersion of accessible elements

among accessible rooms Specific requirements within accessible rooms Access to

rooms and public and common areas Width of door openings Accessible

circulation within units Access to kitchen units Judicial, Legislative, and

Regulatory Facilities (Business and Assembly) Access to secured entrances

(including an accessible security system) Access to courtroom elements (judge's

bench, jury assembly, and deliberation areas, etc.) Access to holding cells (and

amenities) Dispersion of accessible cells Accessible security systems Percentage of

assistive listening systems Detention and Correctional Facilities (Institutional)

Percentage of holding and housing cells or rooms (and amenities) Dispersion of

accessible cells Access to cells and visiting areas Spaces for Children (Educational

and certain Institutional) Access to drinking fountains Access to toilet facilities

(including water closets, toilet stalls, lavatories) Access to dining and work

surfaces Adjusted reach ranges Height of handrails at ramps and stairs Height of

mirrors Height of controls Transportation Facilities (Assembly or Business)

Boarding areas Signs Accessible routes Communication elements Recreational

Facilities (Assembly) Percentage of accessible sauna and steam rooms Number of

accessible means of entry to pool Number of accessible shooting facilities

DESIGN LOADS Occupant loads as described in this chapter are not to be

confused with two other types of design loads required by the codes: dead loads

and live loads. Dead loads include all permanent components of a building's

structure, such as the walls, floors, and roof. Live loads, in contrast, include any

loads that are not the actual weight of the structure itself. They include interior

elements such as people, furniture, equipment, appliances, and books. Other loads

that are sometimes considered live loads but are separate exterior elements include

wind loads, rain and flood loads, snow loads, and earthquake loads. These types of

load factors affect the design of the building's structure. Dead load and live load

calculations are typically done by engineers during the initial design and

construction of a building. Most of the calculations take into consideration that

some of the loads will change during the normal use of a building. For example, in

an office building it is common for interior walls to change and be relocated as

tenants move. The number of people will vary as well. Some interior projects may

require certain live loads to be researched when significant changes are proposed

in a project. The most common situations include (1) adding a wall, such as brick

or concrete, that is substantially heavier than a standard wall; (2) creating a filing

area or library that concentrates the weight at one point; (3) adding a heavy piece

of equipment; and (4) adding an assembly seating area in an existing space. In

most cases, a structural engineer is needed to determine if the existing structure

will hold the added load/weight. If not, the structural engineer will determine how

to add additional support, if possible. Social Service Establishments (Residential)

Access to beds Access to accessible toilet and roll‐in showers DETERMINING

OCCUPANT LOADS In addition to determining the occupancy classification at

the beginning of a project, the occupant load (OL) must also be determined. The

occupant load is used to determine how many people can safely use the space. It

sets the number of occupants for which adequate exiting must be provided from a

space or building. Proper exiting allows people to evacuate safely and quickly.

Usually, the occupant load is determined for each space or building either by using

a load factor given by the code or by establishing a desired number of occupants. If

multiple spaces will be exiting into a common area or converging into a common

path of travel, the codes require that the occupant load for the shared area be

determined by adding the number of occupants who will share a common path to

an exit. These methods can be used to determine the number of people that is

assumed will be using the corridors, stairs, and exits in the event of a fire.

Occupant loads are often based on a relationship between the size and use of the

space or building. In most cases, this means that a larger space allows more

occupants, and the need for more occupants requires a larger space. In some cases,

the number of occupants can be increased without increasing the size of the space.

However, the building codes, such as the International Building Code and the Life

Safety Code, do set limits on the allowable concentration of occupants within a

building. In addition, the occupant load may be needed to determine the occupancy

classification. An example is a restaurant with an occupancy under 50 (Business)

and a restaurant with an occupant load over 50 (Assembly). It is important to

determine the occupant load early in the design process: Not only will it provide

guidance in the correct selection of a building's occupancy classification, but it

affects other codes as well. For example, the occupant load is needed to size the

means of egress components, such as number of exits and the width of corridors

and aisles. (See Chapter 5.) The number of required plumbing fixtures and certain

mechanical calculations also depend on the occupant load. (See Chapter 8.) The

remainder of this chapter explains occupant loads. Occupant Load by Load Factor

Because most means of egress requirements are based on the occupant load, the

code must establish a minimum level of safety. To do this, each code assigns a

predetermined amount of area or square feet (or square meters) required for each

occupant based on the occupancy classification and the specific use of the space.

This predetermined figure is called the load factor. Using the load factor to

determine the occupant load typically generates the lowest number or minimum

number of occupants for which the space must be designed. Note Occupant loads

are typically determined using the load factors given by the codes. Using the Table

Each code discusses occupant load requirements, including load factors and exiting

requirements, within the means of egress chapter. The NFPA codes, including the

LSC, have additional occupant load factors and requirements in each separate

occupancy chapter as well. Figure 3.8 is the load factor table from the IBC, titled

“Table 1004.1.2, Maximum Floor Area Allowances per Occupant.” The NFPA

codes have similar load factor tables. The load factors for a specific use may be

different between the codes. For example, the load factor for a commercial kitchen

in the IBC is 200 sf (18.58 sm); in the LSC, it is 100 sf (9.3 sm). A code may also

have specific load factors for unique uses that may not be included in the other

code. For example, the NFPA codes have a load factor for “concentrated Business

use” (for uses similar to call centers where small cubicles create a higher

occupancy rate than a typical Business use) and Ambulatory health care (which is a

health care use but different than a hospital and a typical doctor's office). The IBC

does not specify a load factor for these uses. Figure 3.8 International Building

Code Table 1004.1.2, Maximum Floor Area Allowances per Occupant (2015

International Building Code, copyright© 2012. Washington, DC: International

Code Council. Reproduced with permission. All rights reserved. www.iccsafe.org).

Note In some cases, it may be possible to design a space for an occupant load less

than that calculated by the load factor. However, it usually requires additional

design documentation and approval by a code official. To use Table 1004.1.2 in

Figure 3.8, you must first determine the specific function of the space. See the first

column titled “Function of Space.” This column lists the different uses for spaces

within a building. Although some uses are similar to occupancy types, you must

choose the specific use of the space. For example, although Assembly is noted as a

general use, there are three main types, including “Assembly with fixed seats” and

“Assembly without fixed seats.” In addition, under the latter, there is the option of

“Concentrated (chairs only—not fixed),” “Standing space,” or “Unconcentrated

(tables and chairs).” Again, the specific use of the space must be considered not the

occupancy type. For example, bowling alleys are considered an Assembly

occupancy. But in this chart, bowling centers is a separate category of use and has

a unique floor area factor. The occupant load factors are listed in the next column

in square feet per person. (A metric conversion is shown at the bottom of the

table.) These areas are given for each of the specific uses regardless of occupancy

classification. For example, if you were designing the classrooms for a college, you

would still use the “Educational, Classroom area” occupant load factor to

determine the occupant load of the space even though the space would be assigned

to a Business occupancy. The load factor indicates the amount of space or area it is

assumed each person present will require. Although the square foot figures may

seem high for one person, they allow for furniture and equipment and, in some

cases, corridors, closets, and other miscellaneous areas. The area for each load

factor refers to the floor area within the exterior walls of a building. The load

factors are designated as gross or net area. The gross area refers to the building as a

whole and includes all miscellaneous spaces within the exterior walls. The net area

refers to actual occupied spaces and does not include ancillary spaces such as

corridors, restrooms, utility closets, or other unoccupied areas. The area of fixed

items, such as interior walls, columns, and built‐in counters and shelving (areas

that are not habitable), are also deducted from the overall area. When net figures

are required, it is assumed that the occupants who are using an ancillary area would

have left the occupied space to do so and, therefore, would already be taken into

account. For example, a person in the corridor of a school would most likely be a

student or teacher already accounted for in a classroom. However, you must

consider the actual use of a space, even a corridor. The Formula The formula that

is used with the load factor tables is Note The load factor does not mean that each

person is required to receive a particular amount of square feet (square meters)

when space planning a project. The figure is used only to determine an occupant

load. The placement of furniture, equipment, and walls will affect the size of the

final space. To determine the occupant load for a building or space, take the area of

the interior space and divide it by the load factor for the appropriate building type

and/or use. If the space or building has more than one type of use, the same is done

for each area according to its use and added together. This provides the number of

occupants that is allowed in the space. If the total results in a fraction over a half of

an occupant, round up to the nearest whole number. Depending on the project,

calculations for separate areas and separate occupancies may also need to be made

and added together. The final occupant load indicates the number of occupants for

which the space must be designed. Note The NFPA codes give load factors in

square feet and in metric dimensions. The IBC provides a metric conversion at the

bottom of the load factor table. Example 1 To further understand the difference

between gross and net area and how to use the load factor table, refer to the floor

plan for a library in Figure 3.9. “Library” is listed separately in the IBC table in

Figure 3.8. This building type is further divided into two separate functions:

reading rooms and stack area. A study room, corridor, and utility closet are also

noted on the plan. These will have to be addressed as well. The occupant load for

each separate function must be determined separately. Figure 3.9 Occupancy load

example: Single occupancy (Library) (1 square foot = 0.0929 square meter). Note

Gross area includes all areas within the exterior walls. Net area consists of all areas

within the exterior walls minus ancillary spaces such as corridors, restrooms, utility

closets, and other unoccupied areas. The load factor for the stack area of the library

is indicated in the table in Figure 3.8 as 100 gross square feet (9.3 sm). So, the area

measurement should include the entire stack area with aisles, reference area,

checkout counter, and so forth. The occupant load factor for the reading rooms is

indicated to be 50 net square feet (4.6 sm), meaning that the area should not

include ancillary spaces. Although there is not a specific function listed in the table

in Figure 3.8, a study room use is similar to a small conference room. A small

conference room may be determined by using the Assembly‐Unconcentrated

(tables and chairs). The load factor for this use is 15 net square feet (1.39 sm). Both

the reading room and the study room areas call for net load factors. Therefore, the

corridor or the utility closet adjacent to the reading rooms on the floor plan should

not be included when determining the area of the reading room or study room.

These areas are essentially left out of the load factor calculation because they are

not considered to contribute additional occupants to the library. Using the

dimensions of the floor plan and the occupant load formula to determine the area

for each space, Figure 3.9 shows how to determine the occupant load for the entire

library. Rounding up, the total occupant load is 40 people. Example 2 Sometimes,

load factors can be used in a slightly different way. If the area required for a

particular occupancy or use needs to be determined, the load factors may help

establish the space requirements. This may be helpful in the programming stage of

a project. For example, if planning a new office space for a client with 125

employees, the table can be used to look up the occupant load factor under

Business areas (100 gross square feet, or 9.3 sm). Multiply this factor by the

number of people intended to occupy the space (125) to determine the minimum

size of the space needed. In this case, at least 12,500 square feet (1161.3 sm) will

be required, according to the codes. This can be done for a smaller use such as a

break room or conference room as well. Although this will provide a good estimate

and the minimum required by code, typically other program requirements must be

added to that area to determine the final size of a space or building. Modifying the

Occupant Load In some cases, it might be desirable to have more people occupy a

space than are determined by the load factor. However, if an increased occupant

load of a space is allowed, additional exiting for the increased number of occupants

must typically be provided. This may require providing additional diagrams

showing aisles, exit widths, seating configurations, and/or locations of fixed

equipment to the code official for approval. Note New occupant load factors

added in recent editions of the IBC include day care centers and exhibit gallery and

museums. For example, a client is developing a restaurant and he has a space that

is 5000 square feet (464.5 sm) for use as the dining area (Assembly). Referring to

the load factor table in Figure 3.8, the load factor is 15 gross square feet (1.4 sm)

for an “Assembly without fixed seats, Unconcentrated (tables and chairs).” By

dividing 5000 square feet (464.5 sm) by 15 gross square feet (1.4 sm), the result is

an occupant load of 333 occupants. However, if the client wanted to be able to seat

400, then 400 would be considered the desired occupant load—the modified

number. The means of egress (i.e., exits, aisles, corridors, and number of doors)

would then be designed for an occupant load of 400. That would also be the

maximum number allowed within the space at any one time. Making sure that the

space can be designed to handle the increased exiting requirements and other

accessible clearances is also necessary. When designing for an increased occupant

load, it is advisable or may be required to review it with the code official early in

the design process. There may be instances when a reduced number is desirable so

that a space is designed for a number of occupants less than the calculated load.

For example, a workshop may not typically be occupied by the number of

occupants determined by the load factor because of the size and amount of

equipment used in the room. Generally, designing for a lower number is not

allowed. Similar to designing for an increased occupant load, designing for a

reduced number would require approval by the code official. Justifying the use and

the reduced number would be required as well. In addition, to allow the lower

occupant load, the code official can require special conditions and limitations for

use of the space. Remember, designing the space for the lower occupant load can

affect the future use of the space because of the lower means of egress capacity.

Occupant Load for Primary and Secondary Spaces When one or more smaller

spaces exits into a larger or primary space before reaching the final exit, the codes

usually require that the occupant load of the primary space include the occupant

loads of the secondary spaces that exit through it. Two examples are shown in

Figure 3.10. The business offices are secondary spaces within the Business

occupancy. Occupants must walk through the open office area in order to exit the

space. However, the training room would also be considered a secondary space,

since it too must empty through the open office area. In this case, the occupant load

for the large training room in Figure 3.10 should be calculated separately using an

Assembly (A) factor, not the load factor of the main Business (B) occupancy.

When these separate calculations are added together, they provide an occupant

load that more accurately addresses the use of the space. Figure 3.10 Occupant

load example: Primary and secondary spaces. Note If the allowable occupant load

of a space needs to be increased, a maximum load factor of 7 square feet (0.65 sm)

could be used. This is the maximum density allowed by the code. An accessory

space can sometimes be considered a secondary space as well. For example, the

occupant load for the design center (B) in Figure 3.4B should be added to the

occupant load of the Mercantile (M) portion of the furniture store, since the

occupants of the design center must walk through the store to exit the building.

Each would be calculated separately according to the load factor for its use. This

total would be used to determine the exiting from the primary space. Occupant

Load for a Building Floor Whenever there is more than one use or occupancy

classification on the same building floor, additional calculations are typically

required. If a building floor is occupied by a single tenant but has a variety of

functional spaces such as offices, cafeteria, and locker rooms, the occupant load of

each area must be calculated. These will be added together to determine the total

occupant load of the floor. Likewise, if the floor has multiple tenants that may be

different occupancies such as Business, Mercantile, and Assembly, the occupant

load must be calculated for the separate tenants using the load factors for the

different functions with the individual tenants. The exiting requirements for each

tenant space must be designed for their occupant load. Further, if these

occupancies or tenants share common spaces such as exiting corridors or

restrooms, the occupant load of each tenant is then added together to determine the

total occupant load for the floor. This will be used to establish the requirements for

the common areas (including public toilet facilities) and the exiting requirements

for the entire floor. (This is described more in Chapter 5.) This process is similar

whether calculating the occupant load under the IBC (mixed occupancies) or the

NFPA 101 (mixed‐multiple occupancies.) A simple example is shown in Figure

3.11. In this example, there is a mixture of Mercantile (M) and Business (B) spaces

on the first floor and multiple Business (B) spaces on the second floor. Figure 3.11

Occupant load example: Mixed/multiple occupancy building (1 square foot =

0.0929 square meter). One way to figure the occupant load for the first floor is to

calculate the occupant load separately for each tenant space and required common

areas and then add them together. Another way (as shown in Figure 3.11) is to

combine the areas for all the occupancy classifications and uses that are the same

(i.e., all the Business occupancies) and then use the load factor for that use. The

same would then be done for the Mercantile occupancies. In this case, because a

gross load factor is required, the public areas (i.e., lobby, restrooms, main corridor)

will also have to be included in the calculations. Typically, this would be

proportionally divided among the different occupancy types, as shown in Figure

3.11. (See the note at the bottom of the figure.) Once the occupant load for each

occupancy/use or each tenant is determined, add them together with the common

areas to get the total occupant load for the whole floor. The total occupant load on

the first floor is 205. The same process is used for the second floor, as shown in

Figure 3.11. However, in this case there is only one occupancy/use type. The total

occupant load for the second floor is 124. The occupant load for each floor

(including common areas) will be used for code requirements such as exiting,

which affect the entire floor and the stairs. (See Chapter 5.) It will also be used to

determine the number of plumbing fixtures in the common toilet facilities on each

floor. (See Chapter 8.) Areas with Multiple Uses Some buildings or building areas

are used for different purposes at different times. For example, a church fellowship

hall might be used for a large assembly one night and as a cafeteria the next. The

following weekend, it might be used as a gymnasium or exercise room. In other

words, any area of a building that has more than one function is considered to have

multiple uses. The occupant load is determined by the use that indicates the largest

concentration of people. Several calculations may be required to determine which

occupancy will provide the largest number. Occupant Load for Fixed Seats Fixed

seating arrangements are common in some building types, especially in Assembly

occupancies. The seats are considered fixed if they are not easily moved and/or if

they are used on a relatively permanent basis. Instead of using the standard formula

for calculating the occupant load when separate fixed seats are present, the actual

seats are counted. For example, the occupant load in a movie theater, as shown in

Plan A of Figure 3.12, would be determined by the number of seats used in the

space (including spaces specifically created for wheelchair users). Figure 3.12

Occupant load example: Occupancies with fixed seats. Note When reading code

tables, it is important to read all the footnotes at the bottom of the tables for

additional information and possible exceptions. Counting seats with arms is self‐

explanatory. However, fixed seating may also consist of continuous seating such as

benches, bleachers, and pews. Each of the codes provides a variable (either in the

occupant load table or the text) to be used for continuous seating. They typically

allow 18 linear inches (457 mm) of seating for each occupant. If, for example, a

church has 28 pews and each pew is 12 feet long, as shown in Plan B of Figure

3.12, the 18‐inch (457 mm) variable would be used. A 12‐foot pew equals 144

inches (3658 mm). Divide the 144 (3658 mm) by the 18‐inch (457 mm) variable to

get 8 people per pew. Because there is a total of 28 pews, this church has an

occupant load of 224 people (28 pews × 8 people/pew). Note The continuous

seating variable will not always evenly divide into the length of the seating.

Usually, if the remaining fraction is one‐half or greater, round

Kennon, Katherine E.; Harmon, Sharon K.. The Codes Guidebook for Interiors

(pp. 181-209). Wiley. Kindle Edition.

Booth seating is another type of continuous fixed seating. Booth seating usually

has a separate variable provided by the codes. The typical increment is 24 inches

(609.6 mm). For example, Plan C in Figure 3.12 shows several types of booth

seating. Each should be calculated separately. Measure the length of the bench

along the front edge (especially at corners) and divide by 24 inches (609.6 mm).

Add all the calculations together to determine the occupant load for the bench

areas. This would be added to the occupant loads of the other seating areas within

the space to determine the total occupant load of the restaurant. All areas of a

building or space have to be included in the occupant count. If the space has

different types of seating and different types of activities occurring, each area

would be assigned by its specific use. For example, a nightclub might have fixed

seating in one area, tables and chairs in another, and a dance floor in another. In

this case, calculate the occupant load for all the different areas separately and add

them together to get the final count. Occupant Load for Unusual Uses There may

also be occasions when the building type or the use of a space is not typical. The

occupant load factors given in the code table may not be appropriate for a unique

use, or a specific occupancy use may not be listed on the table. On other occasions,

a space may not clearly fit into one of the use categories. When this occurs, it is

important to meet with a code official for guidance. Typically, only the code

official can approve a different or unique load factor. This decision should be made

at the beginning of a project, because occupancy classifications and many of the

codes that will apply depend on the determined occupant load. Note Open areas

adjacent to spaces with fixed seats may require additional occupant load

calculations. The open area may be considered standing space and increase the

occupant load. USING THE OCCUPANT LOAD The occupant loads determined

at the beginning of a project will be used again later in the code research to

determine several aspects of the design. Occupant loads will be used to determine

the capacity of the means of egress, such as the number of exits and the width of

the exits. They will also be used to determine the number of plumbing fixtures and

to size a mechanical system. (This is discussed in Chapters 4 and 7.) The space

should be designed to be adequate for the occupant load and the occupant load

should be appropriate for the intended use. Also be aware that changes in the

occupant load may affect the occupancy classification and many of the applicable

code requirements. It should be clear that these have an interactive relationship that

can potentially affect several aspects of the design. Note Every assembly room or

Assembly occupancy usually requires the approved occupant load to be

permanently posted near the main exit from the space. A typical sign might read:

“Occupancy by more than 100 persons is dangerous and unlawful.” In all cases,

adequate means of egress must be provided for the number of people who will be

occupying a space or building. Once the occupant load is set and the means of

egress have been designed, the number of people allowed within a space cannot

exceed that number. For Assembly uses, the approved occupant load is required to

be posted for each space. In other spaces, a code official may require the approved

occupant load to be posted where a modified occupant load has been used to

design the space. Exceeding the posted allowable occupant load is unsafe and

unlawful. RESEARCH AND DOCUMENTATION It is important to accurately

determine and document both the occupancy classification(s) and the occupant

load(s) at the beginning of a project, since most code requirements will depend on

them. For some projects, the occupancy classification may be straightforward or

already determined. For some, you must consider the risk factors and unique

conditions that exist within the space or building. Compare them to the definitions

of each occupancy classification and/or subclassifications. From what you know

about the activities within the space and these risk factors, you should be able to

determine the correct occupancy classification. If hazards are present, consider

them as well. (Each of the code publications lists the types of hazards to look for

and whether they are explosive, fire, physical, or health hazards.) It may not

always be necessary to get approval from your code official at this point in a

project, but each situation is different. (See the section “Preliminary Review” in

Chapter 11.) You do not want proceed with research or design if it is not clear.

Note Not only can a building have more than one occupancy, but each occupancy

can have more than one use for the purpose of determining the occupant load.

Therefore, one building or a large tenant space could require a number of

calculations. Keep in mind that you may have more than one type of occupancy

within the space or building, incidental uses, accessory uses, mixed occupancies

(separated or nonseparated), or multiple uses (mixed or separated) as discussed in

this chapter. You need to document this as well as it may affect other aspects of the

project like location of rated walls (discussed in later chapters). It may be helpful

to create a diagram of the different uses and occupancies in the space or building.

Also, determine if the space will be considered new or existing according to the

codes. This will be important if you are using the LSC. (You may also be required

to use the International Existing Building Code.) In the construction documents,

the occupancy classification and occupant load should be stated. Usually this is

included on the coversheet as a diagram or list. You can use the Occupancy

Classification section of the digital Code Checklists provided with this book. This

will help you determine and document the occupancy classification(s) and

occupant load(s) aspects of your project.

Kennon, Katherine E.; Harmon, Sharon K.. The Codes Guidebook for Interiors

(pp. 209-212). Wiley. Kindle Edition.

CHAPTER 5

MEANS OF EGRESS A means of egress is most commonly described as a

continuous and unobstructed path of travel from any point in a building to a public

way. A means of egress comprises both vertical and horizontal elements, including

doorways, corridors, passageways, stairs, ramps, and intervening rooms. The

design of these components is crucial to the safety of the building occupants in

normal use of a building and especially during emergencies. There are two main

strategies for the means of egress: evacuation and “defend in place.” Evacuation

means that the occupants will be provided with a direct path out of the building. In

a defend in place strategy, occupants will go to a specific area, either on the same

floor or on another floor, to wait for assistance and/or be provided with an

alternative method to exit the building. Every means of egress has various

components. This chapter explains how these components work together. The first

half of the chapter concentrates on explaining the components of the means of

egress. The rest of the chapter discusses how to determine the required quantities,

sizes, and locations of the parts of the means of egress. Accessibility requirements

are also discussed throughout the chapter. Although the codes usually separate

means of egress codes and accessibility requirements, they should be considered

together. In most cases, the means of egress will be required to be accessible or

special conditions must be provided. This chapter has combined the discussion of

these topics wherever possible. (The figures typically show the strictest

requirements as well.) Remember that not every type of means of egress mentioned

in this chapter will be used in every interior project. In addition, many existing

buildings will already have the correct number of exits. If working with just one

occupant or tenant in the building, only the exiting within and from that tenant

space may need to be considered. It may generally be safe to assume that the

number and size of the exits and exit stairways have been correctly designed for

the building. However, some projects may require reevaluating the existing exit

requirements and making alterations, especially if the number of occupants has

been significantly increased. This may require more extensive calculations. Either

way, every interior project must meet specific means of egress requirements. Note

There are two basic strategies for means of egress: evacuation of occupants and

“defend in place.” This chapter discusses the wide variety of codes, standards, and

federal regulations that pertain to the means of egress. Some of the requirements

are based on occupant loads, as discussed in Chapter 2. Specific fire ratings are

also required for each means of egress. Chapter 5 explains the fire‐rating

requirements for building materials and assemblies. Chapter 9 explains the

different types of finishes allowed in each area of a means of egress.

COMPARING THE CODES Although the various codes define the parts of the

means of egress in similar ways, the specific requirements can vary. For instance,

all the codes agree that the means of egress include exit accesses, exits, and exit

discharges. However, the required width of exits, allowable length of corridors,

and hourly fire resistance rating of the components and similar requirements may

differ between codes. The building codes and the Life Safety Code (LSC) set most

of the requirements for the various parts of the means of egress. Each of these code

publications has a chapter dedicated to means of egress. In the NFPA codes,

specific requirements are also included in the individual occupancy chapters. In the

LSC, these requirements may also be different for new or existing buildings or

spaces. If a jurisdiction enforces a building code as well as the LSC, these

requirements will have to be compared so that the most restrictive ones are used.

Note The 9/11 Commission Act of 2007 is a federal legislation that calls for the

development of voluntary, private‐sector standards for emergency preparedness.

Some of these standards are included in the LSC appendixes to provide additional

emergency evacuation requirements. The fire codes include requirements that

affect the means of egress as well. In the International Fire Code (IFC), for

example, the chapter titled “Means of Egress” includes several sections that repeat

the information found in the means of egress chapter in the IBC. However, the IFC

also includes maintenance requirements so that the means of egress remain usable

after the building or space is occupied. These include limitations on the use of

decorations, mirrors, and other objects that may obstruct the egress path. In

addition, the IFC includes special requirements for existing buildings that may

allow exceptions to the requirements for new buildings. (See Appendix B.) In the

“Emergency Planning and Preparedness” chapter of the IFC, the code requires that

occupants be made aware of evacuation procedures. This typically includes

announcing the location of exits at assembly events and practicing fire drills in

schools. The fire code also often requires egress patterns to be posted in certain

locations. In addition, staff be instructed and review procedures for evacuation for

certain occupancies. Although these requirements may not directly affect the

design of a space, in some cases development of these diagrams is part of the

project. The ICC Performance Code (ICCPC) also has a chapter dedicated to

means of egress. Additional information is included in the chapter titled

“Pedestrian Circulation.” That chapter includes accessibility criteria as well. Each

NFPA code includes a performance chapter with specific criteria. Although the

ICCPC chapter does not set specific requirements for means of egress, it does

require that a building and its design allow occupants sufficient time to evacuate,

relocate, or have a “defend in place” location. Obviously, this could be achieved in

several ways. The chapter also sets several objectives for safety during an

emergency that affects the means of egress. Although all the same elements of a

means of egress discussed by the prescriptive codes—such as area of refuge, travel

distance, and unobstructed path—can be part of a performance design, those

specific terms are usually not used by performance codes. Instead, the phrases are

more generic, like “safe place,” “appropriate to the travel distance,” and “adequate

lighting.” Therefore, it may not matter if a particular area is a corridor or a

passageway according to the definition of the prescriptive code. Instead, what

matters is how it works within the path to safety. In addition, performance codes

require the designer to consider the characteristics of the occupants, the features of

the design, and the hazards that may exist to identify the specific challenges of

egressing a particular space or building. For example, consider if the occupants can

move to an exit independently, if they can exit at a normal rate or a slower rate, or

should not exit a building for safety or security reasons. Understanding the special

conditions that exist within a building and using performance criteria may allow a

unique and appropriate system of evacuation to be developed. Prescriptive codes

may then be used to define other specific elements of the means of egress, such as

the location of exit signs and emergency lighting. (Rarely are performance codes

used for design of the entire means of egress.) As always, when using performance

criteria, establish the appropriate criteria of the design and then provide supporting

evaluations and information to the code official for approval. Note Many

accessibility requirements are similar in the ICC A117.1 standard and the 2010

ADA Standards; however, both should be checked to make sure the most stringent

requirements are used. Because the means of egress in most cases is required to be

accessible, these requirements must also be reviewed in conjunction with the

appropriate federal or local accessibility regulations or standards. (See Chapter 2.)

In addition to the ADA standards, the ICC A117.1 accessibility standard may

apply because it is referenced by the IBC and/or it may be used as a stand‐alone

standard by a local jurisdiction. As discussed throughout this chapter, accessibility

requirements will affect the size of many of the means of egress components, as

well as the shapes and mounting heights of the various elements that occupants

must use as part of the means of egress. Some of these differences that occur

between documents are explained in this chapter. Others may be found as more

research is done for a specific project. Remember, if there is a conflict in the

requirements, the strictest requirements must be met—in other words, satisfy the

need for both accessibility and safety. In addition, review the means of egress

requirements for the specific occupancy classification(s) of a project. Although

most of the regulations are consistent, some occupancies allow exceptions or have

additional requirements. Some of the exceptions are given in the means of egress

chapters, and others are grouped by occupancy classification in different sections

of the codes. Assembly occupancies especially must be reviewed, as the use of

fixed seats can create unusual egress paths. (See the section “Aisles and Aisle

Accessways” later in this chapter.) Note The Access Board, ICC, and NFPA have

created comparison documents of the accessibility requirements found in each of

their respective publications. These documents can be found on their websites.

MEANS OF EGRESS COMPONENTS Means of egress is a broad term that

encompasses almost every part of a building interior as well as some exterior

elements. Each of the codes divides a means of egress into three main categories:

exit access, exit, and exit discharge. In all cases, a public way is the final

destination of a means of egress. In some cases, an area of refuge will also be a

part of the means of egress, as explained later. The means of egress components

are defined as follows: Note An exterior space can be either an exterior exit

discharge or a public way. To be a public way, the space must be at least 10 feet

(3048 mm) wide and 10 feet (3048 mm) high and be considered a public space.

Exit access: The portion of a means of egress that leads from any occupied area to

the entrance of an exit. It includes any room or space occupied by a person and any

doorway, aisle, corridor, stair, or ramp traveled on the way to the exit. Exit: The

portion of a means of egress between the exit access and the exit discharge or

public way. It is often required to be physically separated from other interior

spaces. It can be as basic as an exterior exit door or it can include enclosed

stairwells and ramps. In some special cases, it can include certain corridors or

passageways. The enclosure for exits are often distinguished from the exit accesses

because they are required to be fire‐resistant rated. (See Chapter 6.) Area of refuge:

A space or area where persons who are unable to use a stairway (or elevator) can

remain temporarily to await instructions or assistance during an emergency

evacuation. Exit discharge: The portion of a means of egress between the

termination of an exit and the public way. It can be inside a building, such as the

main lobby; or outside a building, such as an egress court, courtyard, patio, small

alley, or other pathway to the public way. Public way: The area outside a building

that is legally considered public. Examples include a street, an alley, or a sidewalk.

The area must have a minimum clear width and height of not less than 10 feet

(3048 mm) to be considered a public way. The intent is to be a destination where

occupants would be safe from exposure to a fire in the building. It is important to

understand the relationship of these components and when each exists. The

simplest relationship is when the exit access leads directly to an exit that takes

occupants out of the building. This is shown conceptually in Figures 5.1A and

5.1B. In the first diagram, the exit is simply an exterior door. Figure 5.1 Means of

egress components. In the second diagram, the exit is an exit stair that opens at the

bottom to the exterior of the building. In some cases, an exit does not end at the

exterior of the building or public way but leads into an exit discharge. As shown in

Figure 5.1C, the exit discharge connects the exit to the public way. The exit

discharge can be either inside or outside the building. In either case, the code will

have specific requirements for its use. The typical means of egress assumes that

occupants can exit the building without any special help, including using stairs.

However, at least one “accessible means of egress” must be provided and if more

than one means of egress is provided from a space, at least two accessible options

must also be available. This type of egress path is usable by a greater range of

occupants, including those with mobility limitations who, for example, cannot use

the exit stair to exit the building. In an accessible means of egress, the common

components of a means of egress (i.e., exit access, exit, etc.) meet the same

requirements. It is often the way the occupant reaches the public way that makes it

accessible. For example, an area of refuge may be used. An area of refuge is not

considered the end point for the accessible means of egress, but instead is a place

where people with disabilities can wait for additional help to reach the public way.

As indicated in Figure 5.1D, an area of refuge can occur adjacent to but before

entering an exit stairway or within the exit stairway. In one scenario, emergency

personnel will assist or carry the occupant down the stairway to the public way. In

special cases, an area of refuge can be included in the elevator lobby. In this case,

emergency personnel will assist the occupant to use the specially equipped elevator

to egress the building to the public way. (See Figure 5.13.) In some cases, as

shown in Figure 5.1E, the exit access leads through a horizontal exit to an area of

refuge on the same floor. If necessary, emergency personnel will take disabled

occupants down a stairway or elevator from the area of refuge side of the building.

(See the sections “Areas of Refuge” and “Horizontal Exits” later in this chapter.)

Note An area of refuge is a component of an “accessible means of egress.” In some

cases, it may be considered part of an exit or exit discharge. In order to know the

requirements that apply to a particular space, it is necessary to know whether that

space is part of the exit access, exit, or exit discharge. For example, the finish

classifications required for an area that is an exit access will differ from those for

an area that is part of an exit. (See Chapter 9.) Some means of egress

Kennon, Katherine E.; Harmon, Sharon K.. The Codes Guidebook for Interiors

(pp. 249-258). Wiley. Kindle Edition.

components within a space may be easy to identify. For example, exit stairs are

always considered exits. For others, the path of the occupants may have to be

considered to correctly identify the component and its role within the means of

egress. For example, a corridor may be part of the exit access, exit or exit

discharge. This is demonstrated on the floor plan in Figure 5.2. Figure 5.2 Means

of egress in a typical building.

Kennon, Katherine E.; Harmon, Sharon K.. The Codes Guidebook for Interiors

(pp. 258-260). Wiley. Kindle Edition.

Recognizing that a space could be considered to be more than one part of the

means of egress, the path of the occupant to the exit or public way can help

determine each component in the means of egress. In the floor plan in Figure 5.2,

different shading patterns indicate whether the space is considered an exit access,

an exit, an exit discharge, or a public way. For example, if a person were standing

in the lobby of this diagram, the distance from the person to the exterior door

would be the exit access and the exterior door would be the exit. Once through the

exterior door, the person would be in an exterior exit discharge (egress court),

because, in this case, the sidewalk is the public way. However, for a person coming

down the stairway at the left of the plan and emptying into the lobby, the stairway

is the initial exit component, the lobby is then part of the exit discharge, and the

exterior door is the end of the interior exit discharge because it leads to the exterior

of the building. From that point, the egress court continues as an exterior exit

discharge until it reaches the sidewalk, as previously discussed. When a space can

be considered more than one part of the means of egress, it must meet the

requirements of the most restrictive component. Note If a building or space is only

required to have one exit, it typically must be an accessible means of egress.

Although the parts of an exit can be defined somewhat differently by the various

codes, they all assume that a means of egress will be continuous. This path

provides protection to the occupant from the point and floor of origin to the ground

level and public way. The requirements for the means of egress components ensure

that the level of protection is maintained until the occupant is in the public way.

What follows is a description of the types of means of egress and the various

components of each. Exit accesses are described first. These components are

elaborated in more detail, since similar components in the other means of egress

categories have many of the same requirements. For example, exit access stairs and

exit stairs are used for different purposes and require different fire protection, but

they both use the same tread and riser dimensions, landing widths, handrail

requirements, and so on. EXIT ACCESSES An exit access is the portion of a

means of egress that leads to an exit. It leads an occupant from anywhere in a room

or space to an exit (including the room itself).

Kennon, Katherine E.; Harmon, Sharon K.. The Codes Guidebook for Interiors

(pp. 260-261). Wiley. Kindle Edition.