# Change OF Occupancy: Building Code Definition > How the IFC 2009 define change of occupancy, where the wording differs, and which chapters depend on the term. - Canonical: https://harth.build/resources/glossary/change-of-occupancy/ - Last updated: 2026-09-07 - Data source: Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The [ICC code library](https://codes.iccsafe.org/codes) publishes the current model text and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) show which edition a jurisdiction has adopted; those sources control. ## Key facts | Fact | Value | | --- | --- | | Defined in | IFC 2009 (2009 editions transcribed in this corpus) | | Primary source | IFC 2009 Definitions (model text, not a jurisdiction's adopted text) | | Chapters using the term | 9 (counted across the codes hosted here) | | Wording identical across codes | Single code (compare before citing one code's wording under another) | ## Direct answer Change OF occupancy is a defined term in the International Fire Code (IFC) 2009, in Definitions. The code's own words are: “A change in the purpose or level of activity within a building that involves a change in application of the requirements of this code.” No other I-Code in this corpus defines it, so the IFC 2009 definition is the one to work from. The term is used in 9 chapters of this corpus, most often in Existing Structures (IBC 2009), Scope and Administration (IBC 2009), General Requirements (IFC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted. Record the jurisdiction, the adopted edition, the application date and any local amendment that rewrites the definition before you use it on a live project, because a term redefined by amendment changes every requirement that depends on it. *Content and cited inputs reviewed by [Scott Barrington](https://nz.linkedin.com/in/barrington), Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.* ## What does this term mean? **Change OF Occupancy** — IFC 2009, Definitions: > A change in the purpose or level of activity within a building that involves a change in application of the requirements of this code. ![Labeled code-term definition diagram: Change OF Occupancy: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/change-of-occupancy/diagram-1344.webp) *How the IFC 2009 define change of occupancy, where the wording differs, and which chapters depend on the term.* ## What must be verified before using this guidance? **Change OF Occupancy** is defined once in this corpus, in the [Definitions](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/definitions.md) chapter of the International Fire Code (IFC) 2009: > A change in the purpose or level of activity within a building that involves a change in application of the requirements of this code. ## Where change of occupancy is used in the code The term appears in 9 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next. | Chapter | Code | Mentions | | --- | --- | --- | | [Existing Structures](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/existing-structures.md) | IBC 2009 | 26 | | [Scope and Administration](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/scope-and-administration.md) | IBC 2009 | 3 | | [General Requirements](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/general-requirements.md) | IFC 2009 | 2 | | [Structural Design](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/structural-design.md) | IBC 2009 | 1 | | [Definitions](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/definitions.md) | IFC 2009 | 1 | | [Fire-resistance-rated Construction](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-resistance-rated-construction.md) | IFC 2009 | 1 | | [High-piled Combustible Storage](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/high-piled-combustible-storage.md) | IFC 2009 | 1 | | [Scope and Administration](https://harth.build/resources/building-codes/us-states/new-hampshire/imc-2009/scope-and-administration.md) | IMC 2009 | 1 | | [Scope and Administration](https://harth.build/resources/building-codes/us-states/new-hampshire/ipc-2009/scope-and-administration.md) | IPC 2009 | 1 | ### The term in use How the code actually writes about change of occupancy, quoted from the 2009 text hosted here: > The provisions of this chapter shall control the alteration, repair, addition and change of occupancy of existing structures. — [IBC 2009 §3401.1](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/existing-structures.md) > To the extent that repairs, alterations or additions are made or a change of occupancy occurs during the restoration of the structure, such repairs, alterations, additions or change of occupancy shall comply with the requirements of Section 105.2.2 and Chapter 34. — [IBC 2009 §116.5](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/scope-and-administration.md) > Additions, alterations, repairs or change of occupancy of existing buildings shall be in accordance with Chapter 34. — [IBC 2009 §1613.3](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/structural-design.md) ## The terms change OF occupancy is built out of The definition above leans on 1 other defined term. Each carries its own code definition, and a local amendment to any of them changes what change OF occupancy covers: - **[Building](https://harth.build/resources/glossary/building.md)** — IBC 2009: Any structure used or intended for supporting or sheltering any use or occupancy. ## Change OF Occupancy: what to open, and in what order Every row is a document this term depends on. The [ICC code library](https://codes.iccsafe.org/codes) and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) cover the middle rows. | Check | Where | Confirmed | | --- | --- | --- | | Read the definition in the adopted IFC | Definitions | | | Re-check the requirement that uses it | Existing Structures (IBC 2009) | | | Re-check the requirement that uses it | Scope and Administration (IBC 2009) | | | Re-check the requirement that uses it | General Requirements (IFC 2009) | | | Re-check the requirement that uses it | Structural Design (IBC 2009) | | | Confirm the dependent definition | Building | | | Local amendment to any of the above | Jurisdiction's amendment list | | **A research aid, not a code determination.** The authority having jurisdiction decides which edition and which amendments apply. ## Where can you explore related guidance? - [Explore all glossary guidance](https://harth.build/resources/glossary.md) - [Building: Building Code Definition](https://harth.build/resources/glossary/building.md) - [Construction Documents: Building Code Definition](https://harth.build/resources/glossary/construction-documents.md) - [Registered Design Professional: Building Code Definition](https://harth.build/resources/glossary/registered-design-professional.md) - [Dwelling Unit: Building Code Definition](https://harth.build/resources/glossary/dwelling-unit.md) ## Sources and method Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The [ICC code library](https://codes.iccsafe.org/codes) publishes the current model text and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) show which edition a jurisdiction has adopted; those sources control. ### Source links - [codes.iccsafe.org](https://codes.iccsafe.org/codes) - [iccsafe.org](https://www.iccsafe.org/advocacy/code-adoption-maps/) ## Frequently asked questions ### What is the code definition of change of occupancy? The International Fire Code (IFC) 2009 defines it in Definitions as: “A change in the purpose or level of activity within a building that involves a change in application of the requirements of this code.” The 2009 model text is reproduced here; the definition that binds your project is the one in the edition your jurisdiction has adopted, as amended locally. ### Which parts of the code depend on change of occupancy? In this corpus the term is used across 9 chapters, led by Existing Structures in the IBC 2009. Those are the sections whose scope moves if the definition is amended locally, so read them together with Chapter 2 rather than on their own. ### What is a 3 occupancy classification? Occupancy Classification is a separate defined term. The IFC 2009 defines it as: “For the purposes of this code, certain occupancies are defined as follows:” That is not the same as change OF occupancy, which the IFC 2009 defines as “A change in the purpose or level of activity within a building that involves a change in application of the requirements of this code.” — read both before applying either, and confirm the wording in the edition your jurisdiction has adopted. --- - Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Fchange-of-occupancy%2F - View this page in a browser: https://harth.build/resources/glossary/change-of-occupancy/ - All resources for agents: https://harth.build/llms.txt