Evolution of Change of Occupancy

Model building and fire codes are consistently being updated to increase the level of safety for occupants by adding and revising code requirements. One important term that has evolved over the years is “Change in Occupancy”. Due to various code changes for clarification and confusion between the terms occupancy and use, it may appear that this term has changed through the years, when in fact the intent has remained the same.

The following is the definition for change in occupancy from the 2003-2012 editions of the International Existing Building Code (IEBC)

2003-2012 IEBC: A change in the purpose or level of activity within a building that involve a change in application of the requirements of this code.

This definition was changed in the 2015 IEBC to clarify the intent of the code and remove the vagueness are the phrase “purpose or level of activity” as follows:

2015 IEBC: A change in the use of the building or a portion of a building. A change of occupancy shall include any change of occupancy classification, any change from one group within an occupancy classification or any change in use within a group for a specific occupancy classification.

This code change clarifies the original intent by changing the term purpose or level of activity to use. It also highlights that a change is occupancy can occur without actually changing the occupancy classification.

Another point of confusion centers around the terms use and occupancy. Use and occupancy are often used interchangeably, but do not mean the same thing in the eyes of the code. An occupancy is one of the classifications found in Chapter 3 (A, B, M, etc.) and these classifications can be broken further down into groups (A-1, A-2, A-3, etc.). The use is the actual function of the building or space and is what determines the occupancy group (office (B), night club (A-2), dormitory (R-2), etc.). For example, a gymnasium may have an occupancy classification of Group A-3, but the use of the space is a gymnasium. If the gymnasium is changed to a bowling alley, the occupancy would remain the same, but the use of the space would change, triggering a change in occupancy. Though the definition for change in occupancy has changed through the years, this concept remains the same.

In the 2018 IEBC, the definition was reorganized as a list to make it clear that any of the conditions could be classified as a change in occupancy. The third item in the list was expanded to include the phrase “change in application of the code”, which was the original code language/intent in the earlier versions.

2018 IEBC: A change in the use of a building or portion of a building that results in any of the following:

  1. A change of occupancy classification.
  2. A change from one group to another group within an occupancy classification
  3. Any change in use within a group for which there is a change in application of the requirement of this code.

Looking forward, the definition in the 2021 IEBC will be changed yet again. A new definition for change in use has been added, using the language in item 3 from the 2018 IEBC definition above, and item 3 is changed to simply state change in use (shown below). Even with this new change, the original intent from the 2003 IEBC to the 2021 IEBC remains the same.

2021 IEBC: Change of Occupancy: Any of the following shall be considered as a change of occupancy where the current IBC requires a greater degree of safety, accessibility, structural strength, fire protection, means of egress, ventilation or sanitation than is existing in the current building or structure:

  1. A change in the occupancy classification of a building or structure.
  2. Any change in the purpose of, or a change in the level of activity within, a building or structure.
  3. A change of use

Change of Use: A change in the use of a building or a portion of a building, within the same group classification, for which there is a change in application of code requirements.