ASCE 7-05 Reference Info

Understanding Component Importance Factors & Occupancy Categories

The Component Importance Factor (Ip) of any project will either be assigned as either a 1.0 or a 1.5. If the component of the project is required to function for life-safety purposes after an earthquake (including fire protection sprinklers), if the component contains hazardous materials, or if the component is in or attached to an Occupancy Category IV Structure and it is needed for continued operation of the facility or its failure could impair the continued operation of the facility you will apply an Importance Factor of 1.5 to your project. All other Components Importance Factor (Ip) will be equal to 1.0.

Occupancy Category however is a category used to determine structural requirements based on occupancy which can range from I to IV. The categories are used to classify buildings and other structures based on occupancy level and nature of use. Occupancy Category I buildings represent a low hazard to life in the event of failure, while Occupancy Category IV buildings are considered essential facilities. Occupancy categories differ between building codes, so it is important to make sure and specify which building code is assigned to your project.

Read the reference tables below to determine which occupancy category or importance factor your project may fall under. If you are still confused Contact ISAT to have someone walk you through your project requirements, we are here to help.

Reference Tables and Information From ASCE 7-05

13.1.3 Component Importance Factor

All components shall be assigned a component importance factor as indicated in this section. The component importance factor, Ip, shall be taken as 1.5 if any of the following conditions apply:

The component is required to function for life-safety purposes after an earthquake, including fire protection sprinkler systems.
The component contains hazardous materials.
The component is in or attached to an Occupancy Category IV structure and it is needed for continued operation of the facility or its failure could impair the continued operation of the facility. All other components shall be assigned a component importance factor, Ip, equal to 1.0.

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TABLE 1-1 OCCUPANCY CATEGORY OF BUILDINGS AND OTHER STRUCTURES

Occupancy Category	Nature of Occupancy
I	Building and other structures that represent a low hazard to human life in the event of failure, including agricultural, temporary, and minor storage facilities.
II	All other structures that aren't in categories I, III, or IV.
III	Building and other structures that represent a substantial hazard to human life in the event of failure including: Covered structures the primary occupancy of which is public assembly with an occupant load of 300. Buildings and other structures with elementary-school, secondary-school, or day-care facilities with an occupant load greater than 250. Buildings and other structures with elementary-school, secondary-school, or day-care facilities with an occupant load greater than 500 for colleges or adult-education facilities. Health-Care facilities with an occupant load of 50 or more resident patients without surgery or emergency-treatment facilities. Jails and detention facilities. Any structure with an occupant load greater than 5,000. Power-generating stations, water-treatment facilities for portable water, waste-water-treatment facilities, and other public-utility facilities not included in Occupancy Category IV. Buildings and other structures not included in Occupancy Category IV containing sufficient quantities of toxic or explosive substances that would be dangerous to the public if released.
IV	Buildings and other structures designated as essential facilities, including: Hospitals and other health-care facilities with surgery or emergency-treatment facilities. Fire, rescue, and police stations and emergency-vehicle garages. Designated earthquake, hurricane, or other emergency shelters. Designated emergency-preparedness, communication, and operation centers and other facilities required for emergency response Power-generating stations and other public-utility facilities required as emergency-backup facilities for Occupancy Category IV structures. Structures containing highly toxic materials as defined in Section 307 of the 2006 International Building Code. Aviation control towers, air-traffic control centers, and emergency-aircraft hangers. Buildings and other structures with critical national-defense functions. Water-treatment facilities required to maintain water pressure for fire suppression.