List each occupancy group the code analysis assigns, then check that the room names, uses, furniture and equipment plans, and life safety plans describe the same uses, and that every mixed-use and incidental-use condition is carried into the separations and systems that depend on it. AI can flag conflicts; the architect and the building official decide the classification.
What does IBC Chapter 3 cover?
Chapter 3 of the 2024 IBC, Occupancy Classification and Use, governs how every building and structure is classified by occupancy and use; the groups reflect different levels of hazard and risk to occupants and to neighboring property. Its sections cover occupancy classification and use designation (302) and the groups themselves: Assembly Group A (303, A-1 to A-5), Business Group B (304), Educational Group E (305), Factory Group F (306, F-1 and F-2), High-Hazard Group H (307, H-1 to H-5), Institutional Group I (308, I-1 to I-4), Mercantile Group M (309), Residential Group R (310, R-1 to R-4), Storage Group S (311, S-1 and S-2), and Utility and Miscellaneous Group U (312).
Chapter 3, Occupancy Classification and Use, on ICC Digital Codes is part of the 2024 IBC. ICC’s store still lists the 2027 IBC as a pre-order due in mid-October, and the 2027 edition was not on Digital Codes. Both checked October 7, 2026. Section numbers and titles below are from the 2024 edition; they can move between editions, and states and cities adopt a specific edition with amendments. Record the edition the jurisdiction enforces before citing a section.
This guide follows one chapter. The IBC guide covers the code analysis as a whole, and state codes built on the IBC, such as the California Building Code, may renumber or amend the chapter. What a classification triggers sits elsewhere: special uses in Chapter 4, mixed occupancies and allowable area in Chapter 5, and egress in the Chapter 10 guide.
Gather the code analysis and every sheet that names a use
Collect the code analysis with its occupancy groups, the life safety plans, the floor plans with room names, the furniture, fixture, and equipment plans, the tenant or owner program, the storage and hazardous materials inventory where one exists, the door schedule, and the mechanical and plumbing sheets that size systems by use.
Room names are edited more often than the code analysis. Upload the latest floor plans with the code sheet so a renamed room can be matched to the classification it should carry.
Match each room’s use to its group
| Review question | Sources to compare | Decision to record |
|---|---|---|
| Groups listed | Code analysis, cover sheet, life safety plans | Confirm one list of occupancy groups and where each applies. |
| Room uses | Floor plans, room names, furniture and equipment plans | Find rooms whose name, seating, or equipment suggests a use the code analysis does not list. |
| Assembly spaces | Furniture plans, life safety plan, occupant loads | Check training rooms, break rooms, and lobbies with fixed or loose seating against the groups listed. |
| Storage and hazards | Storage plans, inventory, specifications | Ask the designer to confirm the basis where stored materials could change the group. |
| Mixed and incidental uses | Code analysis, rated wall plans, area plans | Trace each mixed or incidental condition into the separations or other approach it relies on. |
| Systems sized by use | Plumbing fixture counts, ventilation schedules, sprinkler design notes | Identify systems sized for a different use than the floor plan now shows. |
Occupant loads that follow from the use can be checked with the occupant load calculator, and common comments are in occupant load and egress width corrections. The architectural drawing checklist is the working log. Hazardous materials storage follows the NFPA 400 guide where the project cites it.
Example: a storage room becomes a training room
Hypothetical example. A tenant improvement converts a stockroom into a training room with rows of tables and chairs. The floor plan and furniture plan show the new room, while the code analysis still lists the space as storage and the life safety plan carries the old occupant load.
The current floor and furniture plans show this room as a training room with seating, while the code analysis classifies it as storage and the life safety plan carries the earlier occupant load. Please confirm the occupancy classification and update the code analysis and egress information.
The architect confirms the classification and checks whether the change affects separations, egress, and plumbing fixture counts. The building official decides the classification.
Review occupancy classification with Groundbook
Upload the current drawings and specifications to Groundbook, and state the edition, amendments, and review scope in your instructions. Add the IBC Chapter 3 edition the project uses from a copy you are licensed to use, where the license permits uploading it, and the jurisdiction’s published amendments. See how Groundbook works with local and licensed codes.
Compare the code analysis and life safety plans with the floor plans, room names, furniture and equipment plans, storage plans, door schedule, plumbing fixture counts, and mechanical schedules. Flag rooms whose use differs from the listed occupancy group, mixed or incidental uses without a stated approach, and systems sized for a different use. Use the supplied IBC edition and local amendments and cite both sources.
Groundbook links each potential finding to the room, the sheet, and the code section you uploaded.
Document review does not classify occupancies, decide mixed-use approaches, or replace the architect or the building official.