# Use and Occupancy Classification (IBC 2015 Chapter 3) > Classifies every building and space by occupancy group based on the way it is used and the relative hazard to occupants — the foundation for nearly every other code requirement. - Canonical: https://harth.build/resources/building-codes/us-states/alabama/ibc-2015/use-and-occupancy-classification/ ## Direct answer and reference scope Use and Occupancy Classification (IBC 2015 Chapter 3) is presented here as a reference within the IBC 2015 collection for Alabama. Classifies every building and space by occupancy group based on the way it is used and the relative hazard to occupants — the foundation for nearly every other code requirement. Use the [Alabama Division of Construction Management](https://dcm.alabama.gov/bldg_code.aspx) to confirm the code edition currently adopted for the project, and compare the model text with state amendments, local amendments, effective dates and the permit authority's interpretation. The [ICC code library](https://codes.iccsafe.org/codes) is the model-code publication path. This Harth page is a searchable reference transcription, not an official code publication, legal opinion or confirmation that this edition controls a particular address. Record the project jurisdiction, application date, occupancy, construction type and amendment set before relying on a section. Where this page conflicts with an official publication or the authority having jurisdiction, the official source controls. _Authored and prepared by Harth. Review scope: official verification path added; code text and current local applicability have not been independently reviewed._ _Classifies every building and space by occupancy group based on the way it is used and the relative hazard to occupants — the foundation for nearly every other code requirement._ ## 301 — General The provisions of this chapter shall control the classification of all buildings and structures as to use and occupancy. Each building or portion thereof is classified into one or more of the occupancy groups defined in this chapter according to its nature and the hazards to occupants. See Section 302 for the full list of occupancy groups. The classification assigned here drives requirements throughout the code, including the height and area limits in Chapter 5 and the egress provisions in Chapter 10. ![Diagram illustrating IBC 2015 Section 301: General.](https://firebasestorage.googleapis.com/v0/b/strut-2026.firebasestorage.app/o/codes%2Falabama%2Fibc-2015%2Fuse-and-occupancy-classification%2F301.png?alt=media&token=0a4570a2-1ca1-4852-a9c4-1a9abdaae443) ![Labeled code-chapter diagram: Use and Occupancy Classification (IBC 2015 Chapter 3)](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/building-codes/us-states/alabama/ibc-2015/use-and-occupancy-classification/diagram-1344.webp) *Classifies every building and space by occupancy group based on the way it is used and the relative hazard to occupants — the foundation for nearly every oth…* ## 302 — Occupancy Classification and Use Designation Structures or portions of structures are classified with respect to occupancy into one or more of the groups listed below. A space, room, or area is to be classified by the use that most nearly resembles its actual occupancy. Where a structure is proposed for a use not specifically listed, its classification is determined by the building official based on the most similar listed occupancy. - Assembly (Groups A-1, A-2, A-3, A-4 and A-5) — see Section 303 - Business (Group B) — see Section 304 - Educational (Group E) — see Section 305 - Factory and Industrial (Groups F-1 and F-2) - High Hazard (Groups H-1, H-2, H-3, H-4 and H-5) - Institutional (Groups I-1, I-2, I-3 and I-4) - Mercantile (Group M) - Residential (Groups R-1, R-2, R-3 and R-4) - Storage (Groups S-1 and S-2) - Utility and Miscellaneous (Group U) ![Diagram of the ten IBC occupancy groups: Assembly, Business, Educational, Factory, High Hazard, Institutional, Mercantile, Residential, Storage, and Utility.](https://harth.build/codes/alabama/ibc-2015/use-and-occupancy-classification/302.svg) *The ten occupancy groups defined in Section 302.* ### Worked example **Scenario:** A developer is fitting out a 3,500 sq ft ground-floor space as a sit-down restaurant with seating for 120 guests. **Explanation:** Because more than 50 occupants gather to consume food and drink, the space is classified Assembly Group A-2 (see Section 303), not Business Group B. That single decision raises the bar on egress, occupancy load, and fire-resistance requirements for the rest of the project — which is why occupancy is the first thing to lock down. ## 303 — Assembly Group A Assembly Group A occupancy includes, among others, the use of a building or structure, or a portion thereof, for the gathering of persons for purposes such as civic, social or religious functions; recreation, food or drink consumption; or awaiting transportation. > Small assembly spaces and certain accessory religious or community uses may be classified as Group B under Section 304 where the occupant load and area fall below the stated thresholds. ![Diagram illustrating IBC 2015 Section 303: Assembly Group A.](https://firebasestorage.googleapis.com/v0/b/strut-2026.firebasestorage.app/o/codes%2Falabama%2Fibc-2015%2Fuse-and-occupancy-classification%2F303.png?alt=media&token=1f443f82-ea53-4b76-8901-402cc2961bd1) ## 304 — Business Group B Business Group B occupancy includes the use of a building or structure, or a portion thereof, for office, professional or service-type transactions, including the storage of records and accounts. Examples include banks, professional services, outpatient clinics, and educational occupancies for students above the 12th grade. ![Diagram illustrating IBC 2015 Section 304: Business Group B.](https://firebasestorage.googleapis.com/v0/b/strut-2026.firebasestorage.app/o/codes%2Falabama%2Fibc-2015%2Fuse-and-occupancy-classification%2F304.png?alt=media&token=7b86e1e5-19c1-4446-bbe6-8d430bc5285d) ## 305 — Educational Group E Educational Group E occupancy includes the use of a building or structure, or a portion thereof, by six or more persons at any one time for educational purposes through the 12th grade. Religious educational rooms and auditoriums with an occupant load of less than 100 per room or space and accessory to a place of worship are classified as Group A-3. ![Diagram illustrating IBC 2015 Section 305: Educational Group E.](https://firebasestorage.googleapis.com/v0/b/strut-2026.firebasestorage.app/o/codes%2Falabama%2Fibc-2015%2Fuse-and-occupancy-classification%2F305.png?alt=media&token=efd83111-5dcf-41b9-94a9-71c8543279f0) ## Templates - **[Occupancy Classification Worksheet](https://harth.build/projects)** (2d) — A fillable 2D worksheet that walks each space in your project through the Section 302 decision tree to the correct occupancy group. - **[Mixed-Occupancy Model Template](https://harth.build/projects)** (3d) — A starter 3D Frame model with occupancy groups pre-tagged per zone — drop in your geometry and Frame checks separation and area limits as you build. ## Frequently asked questions ### What occupancy group is a restaurant under IBC 2015? A typical sit-down restaurant with an occupant load of 50 or more is classified as Assembly Group A-2 under Section 303. Smaller spaces below the threshold may fall under Business Group B (Section 304). ### Can one building have more than one occupancy classification? Yes. Section 302 allows a building to contain multiple occupancy groups. Mixed occupancies are then handled as separated or non-separated occupancies under the provisions referenced in Chapter 5. ### Who decides the occupancy group for an unusual use? Where a proposed use is not specifically listed, Section 302 directs the building official to assign the classification that most nearly resembles the actual use based on the relative hazard to occupants. --- - Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fbuilding-codes%2Fus-states%2Falabama%2Fibc-2015%2Fuse-and-occupancy-classification%2F - View this page in a browser: https://harth.build/resources/building-codes/us-states/alabama/ibc-2015/use-and-occupancy-classification/ - All resources for agents: https://harth.build/llms.txt