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Lecture 3 | Codes | Gary Parker. IBC 2003 Chapter 3 Use and Occupancy .
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Lecture 3 | Codes | Gary Parker IBC 2003 Chapter 3 Use and Occupancy Occupancy group classifications trigger specific requirements for the allowable area and height of a building, for means of egress, as well as for the type of construction used. The IBC requirements are fundamentally occupancy based. Most of broad sets of code criteria are derived from the basic classification by occupancy. The building official is directed by the code to classify all building or portions of the building into occupancy groups. The classification uses the language “classified in the group which the occupancy most nearly resembles, according to the fire safety and relative hazard involved.” Code provisions have been developed based on fire-safety and relative hazard performance data according to different occupancies.
Occupancy Classifications Occupancy type results from the programmatic requirements given to the designer. Code requirements, as a result, follow from the number of occupants and the hazards to their safety from external and internal factors, since the code looks into the property protection alongside life safety concerns. Hazards are assessed relative to their impact on adjacent properties and by adjacent buildings as well as impact on occupants. Nevertheless, the responsibility for the protection of adjacent properties falls upon the building in consideration. Considerations for occupancy classification include: How many people Are there assembly areas Are people awake or asleep Are people using alcohol Are people undergoing medical treatment Are people free to move or are they restrained. Hazardous occupancies are addresses separately
Incidental Use Areas Uses or occupancies that are incidental to the main occupancy are not considered to have enough impact to warrant their classification as a mixed occupancy. The structure or portion that regards the classification into one of the occupancy groups is dealt with in §302.1 When the occupancy of a building does contain one or more incidental use areas as defined in Table 302.1.1, the areas are considered part of the main occupancy but require fire-resistance-rated separations from the rest of the occupancy according to the requirements of the table. Incidental areas are not applicable to dwelling units.
Accessory Use Areas In cases when the occupancy contains a distinctly different accessory use that takes <10%of the area of any floor of the building or less than the height or area allowed by Table 503, the accessory use need not be separated from the primary occupancy. Exceptions exist for hazardous uses or when required by §302.1.1 as an incidental use area.
Mixed Occupancies In cases when a building has a mix of occupancies that are distinct or extensive enough as separate occupancies, each use is considered a separate and distinct occupancy. The mix of occupancies is addressed in one of the two ways: 1 | Separate Uses An occupancy separation with a fire-resistance rating as defined by Table 302.3.2 need to be provided between separates uses. 2 | Nonseparated Uses The entire building is regulated according to the most restrictive of the height, area and fire protection requirements for each of the multiple occupancies.
Assembly Group (A) These uses bring large number of people together in relatively small spaces. Also, what matters for this classification regards: 1) how spaces are used in relationship to physical features. 2) how spaces are used in relationship to human behavior. The final assessment is done by the building official. Categories constitute examples rather than an exhaustive and definite list of possible assignments. Group A occupancies are defined as having > 50 occupants.
Business Group (B) Office buildings Storage areas, filing do not constitute a separate occupancy and are categorized as B Outpatient clinics and physician offices, even when patients may be rendered incapable of self-preservation by anesthesia. Testing and research labs that do not exceed amounts for hazardous materials are classified as B Educational facilities for junior colleges, universities and continuing education
Educational Group (E) These occupancies are used by >6 people for classes up to the 12th grade. Uses for daycare of >5 children over 2.5 years of age. Those uses with <5 children are classified as occupancy R-3
Factory and Industrial Group (F) Defined by what they are not and a process of elimination. F-1 Moderate-Hazard occupancy and F-2 Low-Hazard occupancy are based on the analysis of the relative hazards of the operations in these occupancies and by determining that they do not fall under the criteria set for group H F-2 includes non-combustible materials. Presumes that There are no public areas The users are familiar with their surroundings and not the occasional visitors.
High Hazard Group (H) There are two sets of criteria for hazardous occupancies. The first is related to the hazard of the materials in use and the quantities of the materials in use. Groups H1 to H4 fall in this category. The second relates to the nature of the use as well as the quantity and nature of materials. Provided that there are area limitations, hazardous materials are allowed in other occupancies.
Group (H) Control Areas The other basic concept in the code provisions for Group H is that of control areas. This applies both to subdivisions of buildings classified as H occupancies and to areas where hazardous materials occur within other occupancies. §307.2 The control area concept is based on that hazard levels are mitigated by passive and/or active fire protection measures. This regards two primary considerations: 1) the nature of the hazard of the material, 2) the level of hazard is primarily related to the quantity of materials with a given area. Control areas must be separated from one another by 1-hour fire-barrier walls and floors having a minimum fire-resistance rating of 2 hrs. For the 4th and succeeding floors above grade, fire-barrier walls must have a 2-hrs fire-resisting rating.
Group (H) Control Areas
Institutional Group (I) Institutional occupancies are those where people have special restrictions placed upon them. The group is subdivided with regard to the ability of occupants to take care of themselves. Hence, categories are defines based on: Number of occupants Age Health and personal liberty Whether they are in the facility during day or night
Group (I) I-1 has >16 people living under supervision in a residential environment on a 24 hrs basis. The occupants can respond to emergencies with little or no assistance from staff. Similar with <16 people is R-4, with <5 as R-3. I-2 has >5 people under supervision on 24 hrs basis. Occupants cannot respond to emergencies unassisted. Hospitals, nursing homes. I-3 has >5 people under restraint or security on a 24 hrs basis. Prisons, detention centers, mental hospitals I-4 has >5 people under supervision on <24 hrs basis. Similar with <5 people fall in R-3.
Mercantile Group (M) Most retail facilities no matter what they sell, fall in this occupancy. This occupancy group includes incidental storage of up to 10% of the total area. Storage larger than 10% classifies them as Group S. There are limits to the quantities of hazardous materials that may be stored in mercantile occupancies without being classified as Group H.
Residental Group (R) Include typical housing units, distinguished mainly by the total number of occupants and the number of days occupants sleep in the facility. R-1 Occupants sleep <30 days, hence they are not familiar with the surroundings. Hotels. R-2 Occupants are permanent, >30 days in >2 dwelling units. Dormitories, long-term boarding homes. R-3 Permanent, >30 days, defined as not meeting criteria for groups R-1, R-2, or Group I. Single family residences and duplexes. R-4 Occupancies used for residential care or assisted living >5 and <16 people. Is used instead of Group I.
Storage Group (S) Storage facilities for materials with quantities or characteristics not considered hazardous enough to be classified as Group H are classified as Group S. S-1 includes Moderate-Hazard Occupancies S-2 includes Low-Hazard Occupancies (non-combustible materials)
Utility and Miscellan. Group (U) This group includes incidental buildings of an accessory nature. These structures are typically unoccupied except for short times. They are typically separated from other uses and subservient to other uses. The group contains also items that are not buildings such as fences and retaining walls.
Cases Case 1 | Office building 17,000 sf, 2 stories, 8,500 sf per floor, reinforced concrete structure, brick walls, unprotected, no sprinklers. What is the occupancy classification ? What is the maximum allowable area per floor ? Case 2 | Office building 30,000 sf, single story, with a 3,000 sf seminar room, with a 2,250 sf storage, unprotected, no sprinklers. What is the occupancy classification ? What is the required separation of occupancies ? What modification would avoid the separation of occupancies ?
Cases Case 3 | Apparel retail boutique, one story, plan 100’x50’, storage 200 sf, steel construction protected, no automatic sprinklers. What is the occupancy classification ? What is the required separation between the store and the storage ? Case 4 | Sophomore textile art studio, 25 students, 8,000 sf, one story, linked to 3,000 sf storage room containing 220 pounds of combustible fiber, automatic sprinkler system. What is the occupancy classification ? What is the required separation of occupancies ? Record the steps for calculation and estimation
Cases Case 5 | Dancing school hall with 45 person maximum occupancy, next to 3 offices of the headmaster, secretary and ticketing. What is the occupancy classification ? What is the required separation of occupancies ? Case 6 | Fireworks fan using one large room of his 3 bedroom apartment for storing 3 cubic feet of class 4 oxidizer. What is the occupancy classification ? What is the required separation of occupancies ? Record the steps for calculation and estimation
