# What are the key Changes in Occupancy Classification & Use (Chapter 3, CBC 2025)? Author: Lovekush Gangwar Author URL: https://www.meltplan.com/blogs/author/lovekush-gangwar Published: 2026-08-25 Category: Code Updates Category URL: https://www.meltplan.com/blogs/category/code-updates Meta Title: What are the key Changes in Occupancy Classification & Use (Chapter 3, CBC 2025)? Meta Description: Lithium-ion hazards, new alcohol thresholds, bigger childcare limits, R-1/R-2 clarity, and MAQ rewrites—here’s everything changing in CBC 2025 Chapter 3. Tags: buildingcodes Tag URLs: buildingcodes (https://www.meltplan.com/blogs/tag/buildingcodes) URL: https://www.meltplan.com/blogs/key-changes-in-occupancy-classification-use-chapter-3-cbc-2025 Chapter 3 introduces major reclassifications in response to new risks associated with **lithium-ion batteries**, changes to **childcare occupancy limits**, **residential occupancy definitions**, and expansions to **storage and factory occupancies**. These updates affect how buildings are classified, which in turn triggers [fire protection](/blogs/key-changes-in-chapter-9-fire-protection-systems-california-building-code-2025) requirements, allowable areas, egress rules, and separation requirements. **Top high-impact changes:** - **Lithium-ion battery activities are now explicitly classified** under Groups B, F, and S. - **Beverage alcohol thresholds raised** from 16% to 20% for F, S, and storage groups. - **Group E childcare rules expanded** for infants/toddlers. - **New clarity for R-1 and R-2 occupancies** (transient dwellings and emergency service quarters). - **Group H rooftop storage** replaces the previous “outdoor storage” terminology. - **Big update to MAQs** for hazardous materials across Table 307.1(1) & (2). ‍ ### Full Detailed Table Of All Changes  -  Chapter 3 SectionTopicDescription of ChangeImpact304.1Group BGroup B Ambulatory care facilities are no longer limited to 4+ patients. Adds “lithium-ion or lithium metal battery testing, research, and development.”Expands when a facility falls under B instead of I-2; formalizes battery R&D as non-industrial occupancy.305.2 ExceptionGroup E ChildcareRemoves limit of max. 5 infants in Group E childcare; now must comply with Sections 305.2.1–305.2.3 or 308.5.1.Larger daycare centers with infants classified more consistently and safely.306.2Group FNow includes beverages >20% alcohol; also includes ESS, lithium-ion batteries, and vehicles powered by Li-ion.Expands F-1 industrial classification for battery-related manufacturing and testing.306.3Group F-2Beverages ≤20% alcohol now counted as low hazard.Useful for breweries/cideries; lowers required protection.307.1Group HHazardous materials on roofs now termed rooftop storage (formerly “outdoor storage”).Important for mixed-use roofs with battery equipment or fuel cells.Tables 307.1(1) & (2)MAQsLarge revisions to allowable quantities for hazardous materials.May trigger more Group H classifications or require more control areas.Table 307.1.1Hazardous Material ExemptionsEntirely new table.Gives clear exemptions for micro-quantities used in labs, campuses, etc.307.3.1ExplosivesAdds Division 1.4 explosives allowed in H-3 occupancies.Expands storage flexibility with safeguards.308.5.1Group E Child Day CareAdds model code section with CA amendments: daycare for >6 but ≤100 children under 36 months allowed at grade level with exterior exit doors.Enables larger infant/toddler care centers with enhanced egress.310.2Group R-1Now includes buildings with 2+ dwelling units whose occupants are transient.Many short-term rentals now fall under R-1.310.3Group R-2Adds emergency services living quarters to the category.Impacts fire stations & emergency response housing.311.2Group S-1Adds moderate-hazard items: aerosol PA3, beverages >20% alcohol, Li-ion batteries, Li-ion vehicle repair garages.Formalizes S-1 requirements for battery vehicles (EV repair shops).311.3Group S-2Low hazard list expanded to beverages ≤20% alcohol.Storage classification alignment with new alcohol thresholds. ‍ ‍ ### Expert Commentary  -  Why These Changes Matter (Architects + Engineers) #### 1\. Lithium-ion battery hazards now permeate OCC, F, and S groups This is a _big deal_. Battery R&D, manufacturing, storage, and even vehicles powered by lithium-ion batteries now trigger automatic Group B, F, or S occupancy classifications. This cascades into: - More sprinklers - More fire barriers - Larger fire area limitations - New egress constraints - New MAQs and control area layouts #### 2\. Alcohol content bump (16% → 20%) Impacts: - Breweries - Distilleries - Retail storage - Warehouses This reduces regulatory burden for many beverage operations. #### 3\. R-1 and R-2 clarifications This directly affects: - Hotels - Short-term rentals - Emergency service housing - Student housing crossover conditions (handled later [in Chapter 11B](/blogs/key-changes-in-chapter-11b-accessibility-to-public-buildings-public-housing-of-cbc-2025#expert-commentary-why-these-accessibility-changes-matter)) ## FAQs ### 1\. What are the biggest occupancy classification changes in the 2025 CBC? The largest changes involve lithium-ion battery hazards, expanded childcare rules, redefined alcohol thresholds for S and F occupancies, new rooftop hazardous material rules, and redefinitions for R-1/R-2 residential occupancies. These changes affect fire protection systems, egress, separation, and allowable area calculations. ### 2\. How does the 2025 CBC classify lithium-ion battery activities? Battery testing, research, development, storage, and even vehicle servicing now appear explicitly in **Groups B, F, and S** depending on use: - **B** for battery R&D/testing - **F-1** for manufacturing or industrial processing - **S-1** for storage or EV repair garages ‍ This removes ambiguity and increases fire/life-safety consistency. ### 3\. Did the CBC change how alcohol content affects occupancy? Yes. The threshold for beverage alcohol increases from **16% to 20%** in F-1, F-2, S-1, and S-2 occupancies. - **≤20%** alcohol → low hazard (F-2 or S-2) - **>20%** alcohol → moderate hazard (F-1 or S-1) This shift reduces regulatory burden for breweries, cideries, small distilleries, and storage facilities. ### 4\. How did Group E childcare rules change? The 2025 CBC removes the old limit of “maximum 5 infants” in Group E daycares. Instead, infant/toddler care must comply with Sections **305.2.1–305.2.3** or **308.5.1**, allowing: - Larger daycare centers with infants - Group E childcare for infants/toddlers located at grade level - Direct exterior exits These changes support childcare expansion in California. ### 5\. What is the new definition of Group R-1 transient occupancy? Group R-1 now includes **buildings with two or more dwelling units where occupants are transient**, such as: - Short-term rentals (Airbnb, VRBO) - Boutique hotels - Student lodging used less than 30 days This may trigger sprinklers, alarms, corridor ratings, and egress upgrades. ### 6\. What changed for Group R-2 in 2025 CBC? Group R-2 now explicitly includes **emergency services living quarters** such as fire-station dormitories.This reduces ambiguity between institutional vs. residential classification and ensures consistent fire/life-safety protections. ### 7\. How does the 2025 CBC handle rooftop hazardous materials? The prior term **“outdoor storage”** is replaced by **“rooftop storage.”** Hazardous materials—including certain gases, flammable liquids, and battery systems—are now more accurately classified when placed on rooftops, affecting: - Fire barrier requirements - Fire department access - Spill control - Curbing & secondary containment ### 8\. What changed in the Maximum Allowable Quantities (MAQs)? Tables **307.1(1)** and **307.1(2)** were heavily revised. Key updates include: - New adjusted MAQs - Clearer hazardous-material categories - Revised sprinklers + control area triggers - New exemptions via Table **307.1.1** This can push some occupancies into Group H more quickly—or offer relief through new exemptions. ### 9\. Are EV repair garages specifically addressed in the 2025 CBC? Yes. EV/LI-ion vehicle repair facilities are now explicitly included in **Group S-1**, along with new guidance on battery risks. This affects ventilation, sprinklers, and separation requirements. ### 10\. How do these occupancy updates affect building design? The changes significantly influence: - Fire resistance ratings - Separation walls - Sprinkler thresholds - Egress sizing - Control area layouts - Smoke detection & alarm systems - Mechanical ventilation and hazardous exhaust Architects and engineers must reassess occupancy decisions early in schematic design. ### 11\. How do battery-related changes impact mixed-use buildings? Battery rooms, storage spaces, and R&D labs may now fall into: - **Group B** (testing, light R&D) - **Group F-1** (industrial processes) - **Group S-1** (storage or vehicle repair) This can trigger: - Fire barriers (1–3 hour) - Dedicated exhaust systems - Sprinklers - Increased structural fire performance ### 12\. What is the purpose of the new hazardous material exemptions table? Table **307.1.1** clarifies when micro-quantities of hazardous materials are exempt from Group H classification—helpful for: - University labs - Small makerspaces - Tech campuses - Biotech startups This creates a clearer pathway for low-hazard innovation spaces. ### 13\. Do the Chapter 3 changes affect ADUs or small residential projects? Indirectly, yes. Clarifications in R-1 and R-2 definitions impact: - ADU classification next to transient units - Mixed transient/permanent occupancy - Small multifamily with short-term rental components ### 14\. Are fire stations or emergency services buildings treated differently? Yes.Emergency services living quarters are now explicitly **Group R-2**, not institutional. This simplifies design and avoids unintended triggers from I-group requirements. ### 15\. Why is lithium-ion reclassification such a big deal? Because lithium-ion battery hazards are causing: - Thermal runaway events - Intense fire loads - Toxic gas emissions - Explosive cell failures The CBC now explicitly categorizes these activities into B, F-1, and S-1 to ensure appropriate safeguards (sprinklers, ventilation, fire-rated separation, etc.). ### 16\. Do these changes increase construction cost? In some cases, yes - especially for battery-related occupancies or changed MAQs. ‍ But many changes **reduce cost** for: - Breweries/cideries (≤20% alcohol) - Daycares (clearer egress pathways) - Micro labs (hazmat exemptions) - Emergency services facilities (R-2 vs I-classification) ### 17\. When should architects reevaluate occupancy classification under CBC 2025? At **concept design**, before planning submittal. Lithium-ion, daycare, short-term rental, and storage shifts can drastically alter: - Sprinkler requirements - Allowable areas - Fire ratings - Egress strategy - HVAC/exhaust provisions ### 18\. How do these changes affect mixed-use development? Lithium-ion activities, revised beverage thresholds, and rooftop hazmat rules may require: - Additional control areas - New fire separations - Rethinking tenant placements - Rerouting egress or mechanical systems ### 19\. Does CBC 2025 harmonize with NFPA or IFC? Yes. Many lithium-ion and hazardous material updates align with: - NFPA 855 (ESS) - IFC battery provisions - Updated MAQ logic Improving consistency across fire/life-safety codes. ### 20\. What should designers do first when applying CBC 2025 Chapter 3? 1. Re-evaluate occupancy classifications at a system level (B, F, S, H). 2. Recalculate MAQs. 3. Map control areas early. 4. Confirm separation & fire barrier requirements. 5. Coordinate with mechanical/fire consultants before schematic design ends. ‍ ## References Ask any code questions on California Building Code (CBC 2025) changes & get instant answers with cited sections [▶ Learn How it works (1 min)](/code) What can you ask? (Sample questions) - When does the 2025 CBC take effect and what editions does it adopt? - What are the key California amendments to the IBC in CBC 2025? - How do Title 24 energy requirements change in 2025? - What accessibility changes are in Chapter 11B of CBC 2025? [Explore Melt Code](/code) 1. ‍ [2022 California Building Code, Title 24, Part 2 (Volumes 1 & 2) with July 2024 Supplement updated](https://codes.iccsafe.org/content/CABC2022P4) 2. [2025 California Building Code Volumes 1 and 2, Title 24, Part 2](https://codes.iccsafe.org/content/CABC2025P1) ### Related Building Code Resources - [Building CodesWhat are the Key changes in Chapter 14 Exterior Walls of CBC 2025?](/blogs/key-changes-in-chapter-14-exterior-walls-of-cbc-2025) - [Building CodesWhat are the Key changes in Chapter 11B Accessibility to Public Buildings & Public Housing of CBC 2025?](/blogs/key-changes-in-chapter-11b-accessibility-to-public-buildings-public-housing-of-cbc-2025) - [Fire & Life SafetyWhat are the Key changes in Chapter 10 Means of Egress of CBC 2025?](/blogs/key-changes-in-chapter-10-means-of-egress-of-cbc-2025) - [Fire & Life SafetyWhat are the key Changes in Chapter 9 Fire Protection Systems California Building Code 2025?](/blogs/key-changes-in-chapter-9-fire-protection-systems-california-building-code-2025) - [Building CodesWhat are the key changes in Chapter 5 General Building Heights & Areas of CBC 2025?](/blogs/key-changes-in-chapter-5-general-building-heights-areas-of-cbc-2025) --- This blog is powered by Superblog. 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