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Differences Between Change of Use and Change of Occupancy Classification

When modifying the purpose of a commercial or residential building, it's crucial to differentiate between a Change of Use and a Change of Occupancy Classification, as defined in building codes. These terms, while related, dictate different requirements and compliance paths under the International Existing Building Code (IEBC).
Certificate of Occupancy
Certificate of Occupancy
Key Definitions

I. Change of Use

A Change of Use occurs when a building's purpose shifts within the same occupancy group but alters its specific use. For instance:
  • Example: Transforming a restaurant (A-2 occupancy) into a nightclub (also A-2).

II. Change of Occupancy Classification
A Change of Occupancy Classification refers to a transition from one occupancy group to another, which may also include a complete change in classification.

For example:
Example 1: Converting a billiard parlor (A-3) into a bar or tavern (A-2).
Example 2: Shifting from a barber shop (Group B) to a café (Group A-2).


Certificate of Occupancy
Certificate of Occupancy
Legal Framework and Compliance

Buildings with lawful uses before code updates can continue operating under their original design, provided they don't pose hazards to life, health, or property. However, any new changes must comply with the latest building codes.

Chapter 10 Compliance
When occupancy changes occur, Chapter 10 outlines mandatory provisions, including:

- Structural adaptations.
- Fire safety updates.
- Means of egress improvements.
- Practical Considerations / Section 101.2.8.1 of the IEBC.

Per Section 1001.1 of the 2015 IFC, “Section 1031 [2015 IFC] provides that:


  • “Every room or space that is an assembly occupancy shall have the occupant load of the room or space posted in a conspicuous place...”
  • the occupant load “shall be calculated as provided in Section 1004.1” of the 2015 IFC.
  • “The capacity of the means of egress shall be calculated as provided in Sections 1005 and 1006” of the 2015 IFC.
  • the occupant load “shall not exceed the capacity of the means of egress.”
  • ”it shall be prohibited for buildings, or portions thereof, to be overcrowded.”
  • means of egress “shall be continuously maintained free from obstructions or impediments.”
  • a posted occupant load for assembly rooms and spaces is applicable specifically to the room or space it was calculated for, not the entire building.
What Information is on a Certificate Of Occupancy?

  • General Building Information
  • Certificate Type
  • Applicable Building Code
  • Building Construction Classification
  • Building Occupancy Group
  • Multiple Dwelling Law Designation (if applicable)
  • Building Size
  • Description of Fire Protection Systems
  • Type and number of open spaces
  • Additional Limitations / Restrictions
List Of Floors with:
  • Maximum number of persons per space
  • Structural live load per floor
  • Building Code Occupancy Group
  • Number of Dwelling or Rooming Units
  • Zoning Use Group per space
  • Description of Each Use.
Mary Shafran | EXPERIENCE DESIGN

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