CBC · California Building Code

Incidental uses and accessory areas (Table 509.1)

Incidental uses are specific higher‑risk rooms (furnaces, certain labs, large laundries, paint shops, etc.) listed in CBC Table 509.1 that must be separated from the rest of the building by a specified fire‑resistance rating or protected by an automatic sprinkler system; incidental spaces inside dwelling units are excepted (see § 509.1 and Table 509.1).

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Last reviewed: July 5, 2026

What the code requires — 2-4 sentences

Incidental uses are specific ancillary rooms or areas in a building that pose a higher risk than the surrounding occupancy and therefore require fire-resistive separation or other special protection. The California Building Code (CBC) directs that incidental uses located within single- or mixed‑occupancy buildings comply with Section 509 and the list and protections shown in Table 509.1; incidental uses serving a dwelling unit are excepted from § 509.1. See § 509.1 and Table 509.1 for the controlling requirements.

Requirements in detail

How to read Table 509.1

  • Table 509.1 lists specific room/area types (e.g., furnace rooms, refrigerant machinery rooms, paint shops, laboratories, large laundries, etc.) that are treated as incidental uses. For each listed room/area the table prescribes the required separation and/or protection (fire‑resistance rating and/or sprinkler protection). See § 509.1 and Table 509.1.

Decision‑relevant dimensions and values

The table below compiles the decision‑relevant items visible in the provided code text. Each row shows the room/area description, the protection required by the CBC, and the primary code reference where that requirement is stated.

Room or area (decision trigger) Required separation and/or protection Code reference
Furnace room where any piece of equipment is over 400,000 Btu/hr input 1‑hour fire separation, or provide automatic sprinkler system Table 509.1; § 509.1
Rooms with boilers where the largest piece of equipment is over 15 psi and 10 horsepower 1‑hour fire separation, or provide automatic sprinkler system Table 509.1; § 509.1
Refrigerant machinery room 1‑hour fire separation, or provide automatic sprinkler system Table 509.1; § 509.1
Hydrogen fuel gas rooms (not Group H) 1‑hour separation in Groups B, F, M, S, U; 2‑hour in Groups A, E, I, R Table 509.1; § 509.1
Incinerator rooms 2‑hour separation and automatic sprinkler system Table 509.1; § 509.1
Paint shops (not Group H) located outside Group F 2‑hour separation; or 1‑hour plus automatic sprinkler system Table 509.1; § 509.1
Laboratories and vocational shops in Group E (not Group H) 1‑hour separation, or provide automatic sprinkler system Table 509.1; § 509.1
Rooms/areas with special hazards in Group E (SFM note) 1‑hour separation (SFM notation in table) Table 509.1; § 509.1
Laboratories in Group I‑2 (not Group H) 1‑hour separation (with note “a” in table) Table 509.1; § 509.1
Laboratories in ambulatory care facilities (not Group H) 1‑hour separation or provide automatic sprinkler system Table 509.1; § 509.1
Laundry rooms over 100 sq ft 1‑hour separation or provide automatic sprinkler system Table 509.1; § 509.1
Group I‑2 laundry rooms over 100 sq ft 1‑hour separation and provide automatic sprinkler system (note “a”) Table 509.1; § 509.1
Group I‑3 cells and Group I‑2 patient rooms with padded surfaces 1‑hour separation and provide automatic sprinkler system (note “a”) Table 509.1; § 509.1

Note: the copy of Table 509.1 available in the provided files shows multiple entries but the preview is partial. The table in the official CBC includes additional entries and notes; consult the full Table 509.1 in the CBC for the complete list and all table footnotes.

Interface with other code requirements

  • Where an incidental use is separated from the remainder of the building by a horizontal assembly, the required fire‑resistance rating for that horizontal assembly is "not less than that required by Section 509" — i.e., horizontal assemblies separating incidental uses must meet the rating in § 509 (see § 711.2.4.5).
  • Many incidental use entries offer an "or" choice: either provide the specified rated separation or provide automatic sprinkler protection (see Table 509.1). That choice interacts with Chapter 9 sprinkler requirements (e.g., automatic sprinkler systems per § 903.3.x where applicable). See § 509.1 and Table 509.1.

Exceptions & special cases

  • Incidental uses located within and serving a dwelling unit are not required to comply with Section 509 (the dwelling‑unit exception in § 509.1).
  • Type IIB, IIIB, and VB construction: the CBC explicitly permits the supporting construction of horizontal assemblies at incidental‑use separations to be non‑fire‑resistance‑rated where the required rating does not exceed 1 hour (see § 711.2.3). That is a construction‑type exception that can affect how incidental separations are detailed.
  • Some entries in Table 509.1 include footnote markers (for example, note “a” in the table). Those footnotes can change the required protection for specific occupancies (e.g., additional mandatory sprinklering in certain Group I‑2 situations). Review the full table footnotes in the CBC to apply those special requirements.

Common mistakes

  • Treating all accessory rooms the same: owners/designers sometimes assume any mechanical, paint, laundry, or lab space is handled as a generic accessory area. Only the specific rooms listed in Table 509.1 are "incidental uses" that trigger § 509 protections; other accessory spaces are addressed elsewhere (e.g., accessory occupancy rules in Chapter 5/§ 508). See § 509.1 and § 508.2.
  • Forgetting the dwelling‑unit exception: incidental‑use rules in § 509.1 do not apply when the incidental area is inside and serving a dwelling unit. Applying § 509 requirements to such a case can lead to unnecessary work.
  • Missing the "or sprinkler" option: many Table 509.1 entries allow either a rated separation or sprinkler protection. Designers sometimes specify both rated walls and sprinklers unnecessarily; conversely, some omit sprinklers when the chosen alternative (rated construction) is not actually provided. Confirm which option the design uses and document it.
  • Overlooking construction‑type exceptions: in Types IIB/IIIB/VB the code has limited exceptions for supporting construction when the separation rating is 1 hour or less. Not applying that correctly can cause conflicts between architectural and structural detailing. See § 711.2.3.
  • Not checking table footnotes: several rows include footnote markers that impose additional constraints for specific occupancies (for example Group I‑2). Always review the full table and the footnotes in the CBC.

Worked example — concrete scenario

Scenario: An owner proposes a mixed‑use building (Group B offices with a small tenant laundry and a mechanical/furnace room). The furnace room contains a unit rated at 450,000 Btu/hr input. The tenant laundry room is 120 sq ft.

Step 1 — Identify triggers in Table 509.1:

  • Furnace room > 400,000 Btu/hr → Table 509.1 requires 1‑hour separation or an automatic sprinkler system.
  • Laundry room > 100 sq ft → Table 509.1 requires 1‑hour separation or an automatic sprinkler system.

Step 2 — Choose compliance approach:

  • Option A (no building sprinkler system): Provide 1‑hour fire‑resistive separations around both the furnace room and the laundry (walls/ceilings/penetration firestopping and doors with appropriate rating), and ensure any horizontal assemblies used to separate the incidental areas meet the rating required by § 509 (see § 711.2.4.5).
  • Option B (building is or will be sprinklered): If the building has an automatic sprinkler system that meets applicable CBC sprinkler requirements, the table permits providing the sprinkler alternative in many entries. Confirm that the sprinkler design meets the Chapter 9 requirements (e.g., system type/occupancy thresholds per § 903.3.1.x) before relying on this option.

Step 3 — Additional checks:

  • If the building is Type VB and you choose the 1‑hour separation option, confirm whether the Type VB supporting construction exception affects required detailing (see § 711.2.3).
  • For any door openings in the separation, select fire doors with the correct hourly rating and proper latching/closing hardware per the door and fire‑protection provisions elsewhere in the CBC.

Related provisions

  • § 509.1 — Section title and general requirement (Incidental uses).
  • Table 509.1 — The specific list of incidental uses and their required separations/protections.
  • § 711.2.4.5 — Horizontal assemblies separating incidental uses must comply with the rating required by Section 509.
  • § 711.2.3 — Exception for supporting construction in Types IIB, IIIB, VB when incidental separations are ≤ 1 hour.
  • Chapter 9 (automatic sprinklers) — Automatic sprinkler options in Table 509.1 interact with Chapter 9 sprinkler provisions (see § 903.3.1.1 / § 903.3.1.2 for system types and thresholds).
  • § 508 — Mixed occupancies and accessory area rules (Table 509.1 applies within single or mixed occupancies as noted in § 509.1).
  • CBC Existing Building provisions (e.g., § 1002.2) — change‑of‑use rules referencing Table 509.1 when an existing area becomes an incidental use.

Code references

Grounded in the retrieved California Building Code — click a citation to read the verbatim passage:

  • CBC § 704.7 High relevance — show source text

    Ducts 704.7, 705.11, 706.11, 707.10, 708.9, 709.8, 710.8, 712.1.10.3, 712.1.6, 713.10, 714.1.1, 717 Encroachment, public right-of-way 3202.3.2 Equipment on roof 1511 Equipment platforms 505.3 Fireplaces 2111 Incidental use room Table 509.1

    Motion picture projection room 409.3 Permit required 105.1, 105.2 Roof access 1011.12 Seismic inspection and testing 1704.3.2, 1705.13.7 Smoke control system 909 Systems Chapter 28 Mechanically Laminated Decking 2304.9.3 Medical Care (see Institutional I-2) 407.1 Medical Gas Systems 427 Membrane Roof Coverings 1507.11, 1507.12, 1507.13 Membrane Structures 2702.2, 3102 Mercantile Occupancy (Group M) 309 Accessible Chapter 11B Alarm and detection 907.2.6.3.4

    Area 503, 505, 506, 507, 508 Covered and open mall buildings 402 Hazardous material display and storage 414.2.5 Height 503, 504, 505, 508 Incidental uses 509

    Interior finishes Table 803.13, 804 Live load Table 1607.1 Means of egress Aisles 1018.3, 1018.4 Stairway, exit access 1019 Travel distance 402.8, 1006.3, 1017.2, 1006.2.1 Mixed occupancies 508.3, 508.4 Accessory 508.2 Live/work units 508.5 Mall buildings 402 Parking below/above 510.2, 510.7, 510.8, 510.9 Special mixed 510.2 Occupancy exceptions 307.1.1 Plumbing fixtures Chapter 29 Sprinkler protection 903.2.7 Standpipes 905.3.3 Unlimited area 507.4, 507.5, 507.13 Merchandise Pad 1018.4

    Metal

    Aluminum Chapter 20 Roof coverings 1504.4.2, 1507.4, 1507.5

    Steel Chapter 22

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    Pedestrian

    Protection at construction site

    3303.2, 3306 Walkways and tunnels 3104, 3202.3.4 Penalties 114.4 Penetration-Firestop System Fire-rated horizontal assemblies

    714.5.2

    Fire-rated walls 714.4.2 Penetrations 714, 717 Fire-resistant assemblies

    Exterior wall 705.11

    Fire barrier 707.7, 707.10 Fire partition 708.7, 708.9 Fire wall 706.9, 706.11 Horizontal assemblies 714.5

    Installation 714.2

  • CBC § 105.6 High relevance — show source text

    INDEX

    Unlimited Area Buildings 507 Unsafe Structures and Equipment (see Structures, Unsafe) 116 Appeals 113, Appendix B Revocation of permit 105.6 Stop work orders 115 Utilities disconnection 112.3

    Unstable Materials 307.3, Table 414.2.5.1, Table 414.5.1, Table 415.6.5, 415.7.1, 415.9 Unusable Space 711.2.6 Use and Occupancy Chapter 3 Accessory 508.2 Classification 302.1

    Detailed requirements based on occupancy and use Chapter 4 Incidental uses 509, Table 509.1 Mixed 508.3, 508.4 Use designation 302.2 Utilities 112

    Service connection 112.1

    Service disconnection 112.3

    Temporary connection 112.2 Utility and Miscellaneous Occupancy (Group U) 312 Accessibility Chapters 11A and 11B Agricultural buildings Appendix C Area 503, 505, 506, 507, 508 Flood provisions Appendix G Height 503, 504, 508 Incidental uses 509

    Live loads Table 1607.1 Means of egress Exit signs 1013.1 Stairway, exit access 1019 Mixed occupancies 508.3, 508.4 Special provisions Private garages and carports 406.3 Residential aircraft hangars 412.4 Sprinkler protection 903.2.11 Travel distance 1006.2.1, 1006.3,

    1017.1 UV Germicidal Irradiation Systems

    1211

    Valuation or Value (see Fees, Permit) 109.3 Vapor Diffusion Port 202 Vapor Retarders 1202.3, 1404.3, 1404.3.2 Vegetative Artificial decorative 419, 419.1 Vegetative roofs 1505.10, 1507.15 Vehicle Barrier 1607.11 Vehicle Barrier Systems 406.4.2, 1607.11 Vehicle Show Rooms 304 Vehicular Fueling 406.7 Vehicular Gates 3110 Vehicular Repair 406.8

    Veneer Cement plaster 1404.16, 1411 Fastening 1404.5 Fiber-cement siding 1404.17, 1411 Glazing 1404.13, 1411 Masonry, adhered 1404.11, 2101.2.1, 2103.2.4 Masonry, anchored 1404.7, 1411, 2101.2.1

    Metal 1404.12

    Plastic 1411, 2605 Slab-type 1404.9, 1411

    Testing Automatic fire-extinguishing systems 904.4

    Automatic water mist systems 904.11.3 Building official required 104.2.3.6 Carbon dioxide systems 904.8 Clean agent system 904.10 Dry chemical systems 904.6 Emergency and standby power 2702.4 Fire alarm systems 907.7, 907.8 Fire pumps 913.5 Fire-resistant materials 703.2

  • CBC § 508.5.4 High relevance — show source text

    [BE] 508.5.4 Egress capacity. The egress capacity for each element of the live/work unit shall be based on the occupant load for the function served in accordance with Table 1004.5.

    [BE] 508.5.5 Spiral stairways. Spiral stairways that conform to the requirements of Section 1011.10 shall be permitted.

    [BE] 508.5.6 Vertical openings. Floor openings between floor levels of a live/work unit are permitted without enclosure.

    [F] 508.5.7 Fire protection. Live/work units in buildings constructed in accordance with this code shall be provided with all of the following:

    1. An automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2.

    2. Smoke alarms in accordance with Section 907.2.11.

    3. Where required by Section 907.2.9.2, a manual fire alarm system.

    Live/work units in buildings constructed in accordance with the California Residential Code shall be provided with an automatic sprinkler system and smoke alarms. The automatic sprinkler system shall comply with California Residential Code Section R309, and smoke alarms shall comply with California Residential Code Section 310.

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    GENERAL BUILDING HEIGHTS AND AREAS

    508.5.8 Structural. Floors within a live/work unit shall be designed for the live loads in Table 1607.1, based on the function within the space.

    Exception: Residential areas of live/work units constructed in accordance with the California Residential Code shall not be required to comply with Table 1607.1.

    [BE] 508.5.9 Accessibility. Accessibility shall be designed in accordance with Chapter 11A and/or 11B, when applicable, for the function served.

    508.5.10 Ventilation. The applicable ventilation requirements of the California Mechanical Code shall apply to each area within the live/work unit for the function within that space.

    508.5.11 Plumbing facilities. The nonresidential area of the live/work unit shall be provided with minimum plumbing facilities as specified by the California Plumbing Code, based on the function of the nonresidential area. Where the nonresidential area of the live/work unit is required to be accessible, the plumbing fixtures specified by the California Plumbing Code shall be accessible.

    SECTION 509—INCIDENTAL USES

    509.1 General Incidental uses located within single occupancy or mixed occupancy buildings shall comply with the provisions of this section. Incidental uses are ancillary functions associated with a given occupancy that generally pose a greater level of risk to that occupancy and are limited to those uses specified in Table 509.1.

    Exception: Incidental uses within and serving a dwelling unit are not required to comply with this section.

    �

    [F] TABLE 509.1—INCIDENTAL USES Col2
    ROOM OR AREA SEPARATION AND/OR PROTECTION
    Furnace room where any piece of equipment is over 400,
  • CBC § 407.2 High relevance — show source text

    407.2 Corridors continuity and separation. Corridors in occupancies in Group I-2 shall be continuous to the exits and shall be separated from other areas in accordance with Section 407.3 except spaces conforming to Sections 407.2.1 through 407.2.6.

    407.2.1 Waiting and similar areas. Waiting areas and similar public-use areas or group meeting spaces constructed as required for corridors shall be permitted to be open to a corridor, only where all of the following criteria are met:

    1. The spaces are not occupied as care recipient’s sleeping rooms, treatment rooms, incidental uses listed in Table 509, in accordance with Section 509, or hazardous uses.

    2. The open space is protected by an automatic fire detection system installed in accordance with Section 907.

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    SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY AND USE

    1. The corridors onto which the spaces open, in the same smoke compartment, are protected by an automatic smoke detection system installed in accordance with Section 907, and the smoke compartment in which the spaces are located is equipped throughout with quick-response sprinklers in accordance with Section 903.3.2.
    2. The space is arranged so as not to obstruct access to the required exits. 5. Each space is located to permit direct visual supervision by the facility staff.

    407.2.2 Nurse stations. Spaces for care providers’, supervisory staff, doctors’ and nurses’ charting, communications and related clerical areas shall be permitted to be open to, or located within the corridor, provided the required construction along the perimeter of the corridor is maintained. Construction of nurse stations or portions of nurse stations, within the envelope of the corridor is not required to be fire-resistive rated. Nurse stations in new and existing facilities see the California Code of Regulations, Title 19, Division 1, Chapter 1, Subchapter 1, Article 3, Section 3.11(d) for storage and equipment requirements.

    In detention or secure mental health facilities, the provisions above applies to enclosed nurse stations within the corridor.

    407.2.3 Psychiatric treatment areas. Areas wherein psychiatric care recipients who are incapable of self-preservation are housed, or group meeting or multipurpose therapeutic spaces other than incidental uses in accordance with Section 509, under continuous supervision by facility staff, shall be permitted to be open to the corridor, where the following criteria are met:

    1. Each area does not exceed 1,500 square feet (140 m [2] ).
    2. The area is located to permit supervision by the facility staff.
    3. The area is arranged so as not to obstruct any access to the required exits.
    4. The area is equipped with an automatic fire detection system installed in accordance with Section 907.2.
    5. Not more than one such space is permitted in any one smoke compartment.
    6. The walls and ceilings of the space are constructed as required for corridors. 407.2.4 Gift shops. Gift shops and associated storage that are less than 500 square feet (455 m [2] ) in area shall be permitted to be open to the corridor where such spaces are constructed as required for corridors.
  • CBC § 1010.2.3 High relevance — show source text

    Hardware 1010.2.3 Toilet facilities for public pools Chapter 29

    Technical Production Areas 410.2.2, 410.5.3 Telephone Exchanges 304 Telescopic Seating (see Bleachers) Temporary Structures 3103 Certificate of occupancy 108.3, 111.3 Conformance 108.2, 3103.1.2 Construction documents 3103.2 Encroachment, public rights-ofway 3202.3 Flood provisions G113 Means of egress 3103.4 Permit 108.1, 3103.1.3 Power, temporary 108.3, 112.2 Structural 3103.6 Termination of approval 108.4 Tenant Separation Covered and open mall building 402.4.2.1, 708.1 Tents (see Temporary Structures) Termites, Protection From 2304.12 Terra Cotta 1404.10, 1411

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    Unlimited Area Buildings 507 Unsafe Structures and Equipment (see Structures, Unsafe) 116 Appeals 113, Appendix B Revocation of permit 105.6 Stop work orders 115 Utilities disconnection 112.3

    Unstable Materials 307.3, Table 414.2.5.1, Table 414.5.1, Table 415.6.5, 415.7.1, 415.9 Unusable Space 711.2.6 Use and Occupancy Chapter 3 Accessory 508.2 Classification 302.1

    Detailed requirements based on occupancy and use Chapter 4 Incidental uses 509, Table 509.1 Mixed 508.3, 508.4 Use designation 302.2 Utilities 112

    Service connection 112.1

    Service disconnection 112.3

    Temporary connection 112.2 Utility and Miscellaneous Occupancy (Group U) 312 Accessibility Chapters 11A and 11B Agricultural buildings Appendix C Area 503, 505, 506, 507, 508 Flood provisions Appendix G Height 503, 504, 508 Incidental uses 509

    Live loads Table 1607.1 Means of egress Exit signs 1013.1 Stairway, exit access 1019 Mixed occupancies 508.3, 508.4 Special provisions Private garages and carports 406.3 Residential aircraft hangars 412.4 Sprinkler protection 903.2.11 Travel distance 1006.2.1, 1006.3,

    1017.1 UV Germicidal Irradiation Systems

    1211

  • CBC § 2202.2 High relevance — show source text

    Seismic provisions 2202.2, 2204.2, 2206.1.1, 2207.1.1, 2209.2, 2210.2 Special inspections 1705.3 Stainless Steel 1705.2.2, 2203, 2205 Stairs, ladders and guarding for steel storage racks and industrial steel work platforms 2213 Storage racks 2209, 2213 Structural steel 2202

    Stone Masonry 2103.1, 2113.11.2.1 Stone Veneer 1404.8 Slab-type 1404.9 Stop Work Orders 115 Storage Occupancy (Group S) 311 Accessibility Chapter 11B Accessory 311.1.1 Area 406.5.4, 406.5.5, 406.6.1, 503, 505, 506, 507, 508 Equipment platforms 505.2 Group provisions Hazard storage, low, Group S-2 311.3 Hazard storage, moderate, Group S-1 311.2 Hazardous material display and storage 414.2.5 Height 406.5.4, 406.6.1, 503, 504, 505, 508, 510 Incidental uses 509

    Interior finishes Table 803.13, 804 Live loads Table 1607.1 Means of egress Aisles 1018.5

    Stairway, exit access 1019 Travel distance 1006.3, 1017.2, 1017.2.2, 1006.2.1 Mixed occupancies 508.3, 508.4 Accessory 311.1.1, 508.2 Parking above/below 510.3, 510.4, 510.7, 510.8, 510.9 Special mixed 510.2

    Occupancy exception 311.1.1 Plumbing fixtures Chapter 29 Self-service storage 311.2 Special provisions Aircraft related occupancies 412 High-piled combustible 413 Parking garages 406, 510 Sprinkler protection 903.2.10 Unlimited area 507.3, 507.4, 507.5 Storage Racks, Steel 2209 Storm Shelter 423

    Education 423.5 Emergency operation facilities 423.4 Refuge area (see Refuge Area) Risk category 1604.5.1 Strength Design requirements 1604.2 Strength Design 1604.1 Factored load 202

    Limit state 202

    Load combinations 1605

    Load factor 202

    Masonry 2108 Structural Composite Lumber 2303.1.10, Table 2304.11 Structural Design Chapter 16, 107.2.7, Chapter 16A Aluminum Chapter 20 Concrete Chapters 19 and 19A Foundations Chapters 18 and 18A Masonry Chapters 21 and 21A Steel Chapters 22 and 22A Wood Chapter 23 Structural Glued-Laminated

    Timber 2303.1, Table 2306.1 Structural Observation 1704.6

    Stucco 2512

  • CBC § 603.1 Medium relevance — show source text

    Design Professional in Responsible Charge) Architectural Trim 603.1, 1408.3 Area, Building Chapter 5, 506, Table 506.2 Accessory uses 508.2.3 Aircraft hangars, residential 412.4.5 Allowable area determination 506.2,

    506.3

    Basements 506.1.3 Buildings on same lot 503.1.2 Covered and open mall building 402.4.1, 402.4.1.1 Enclosed parking garage 406.6.1, 510.3 Equipment platforms 505.3.1 Frontage bonus 506.3 Incidental uses 509.3

    Limitations 503, 506 Membrane structures 3102.4

    Mezzanines 505.2.1 Mixed construction types 3102.6 Mixed occupancy 508.2.3, 508.3.2, 508.4.2

    Modifications 506, 510 Occupied roof 503.1.4 Open mall building 402.4.1 Open parking garage 406.5.4, 406.5.4.1, 406.5.5, 510.2, 510.3, 510.4, 510.7, 510.8, 510.9 Private garages and carports 406.3.1 Special provisions 510 Unlimited area 503.1.1, 503.1.3, 506.1.1, 506.2, 507 Area for Assisted Rescue, Exterior (see Exterior Area for Assisted Rescue) Area of Refuge (see Also Accessible Means of Egress) 202

    Requirements 709.4.2, 1009.6 Signage 1009.10, 1009.11, 1009.9, 1013.4, 1143A, 11B-216, 11B-703 Two-way communication 1009.6.5, 1009.8, 1026.6 Where required 1009.2, 1009.3.3, 1009.4.2 Assembly Occupancy (Group A) 303, 1030 Accessibility Chapters 11A and 11B Alarms and detection 907.2.1

    Area 503, 506, 507, 508 Bleachers (see Bleachers) Folding and telescopic seating (see Bleachers) General 303.1 Grandstands (see Grandstands) Group-specific provisions A-1 303.2

    A-2 303.3

    A-3 303.4

    A-4 303.5

    Motion picture theater 409, 507.12 Special amusement areas 411 Stages and platforms 410 Height 503, 504, 505, 508, 510 Incidental uses 509 Interior finishes Table 803.13, 804 Live load Table 1607.1 Means of egress Aisles 1018.2, 1030.9, 1030.10,

    1030.11

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  • CBC § 803.13 Medium relevance — show source text

    Incidental uses 509 Interior finishes Table 803.13, 804 Live load Table 1607.1 Means of egress Aisles 1018.3

    Stairway, exit access 1019 Travel distance 1006.3, 1017.2,

    1006.2.1

    Mixed occupancies 508.2, 508.3, 508.4 Accessory 303.1.2, 508.2 Ambulatory care facilities 422 Assembly 303.1.2

    Assembly spaces 1030 Exit signs 1013.1 Guards 1015.2, 1030.17 Main exit 1030.3

    Open air 1005.3.1, 1005.3.2, 1006.3, 1009.6.4, 1019.3, 1027, 1030.6.2 Panic hardware 1010.2.8, 1010.4.1 Smoke-protected 1005.3.1, 1005.3.2, 1006.3, 1009.6.4, 1019.3, 1027, 1030.6.2 Travel distance 1006.2.1, 1006.3, 1017.2, 1030.7 Mixed occupancies 508.3, 508.4 Accessory 508.2 Education 303.1.3

    Live/work units 508.5 Mall buildings 402 Other occupancies 303.1.1, 303.1.2, 303.1.3 Parking below/above 510.7, 510.9 Religious facilities 303.1.4 Special mixed 510.2 Motion picture theaters 409, 507.12 Occupancy exceptions 303.1.1, 303.1.2, 303.1.3, 303.1.4, 305.1.1, 305.2.1 Plumbing fixtures Chapter 29 Risk category Table 1604.5 Seating, fixed (see Seating, Fixed) Seating, open-air assembly seating 1030.6.3 Seating, smoke-protected 1030.6.2 Sprinkler protection 410, 504.3, 506.2, 507.12, 507.4, 507.6, 507.7, 903.2.1 Stages and platforms 410 Standpipes 905.3.2, 905.5.1 Unlimited area 507.12, 507.4, 507.4.1, 507.6, 507.7 Assisted Living (see Group I-1 and Group R-4) 308.2, 310.5, 420 Atmospheric Ice Loads 1614 Atrium 404

    Alarms and detection 404.4, 907.2.15 Enclosure 404.6, 707.3.6 Interior finish 404.8 Means of egress 404.9, 404.10, 404.11, 1006.3.2, 1017.3, 1019.3, 1023.2,

    1028.2

    Smoke control 404.5, 909 Sprinkler protection 404.3 Standby power 404.7 Travel distance 404.9, 1006.2.1, 1006.3, 1017.2

    Use 404.2

    Attic 202

  • CBC § 1607.1 Medium relevance — show source text

    STRUCTURAL DESIGN

    SECTION 1607—LIVE LOADS

    1607.1 General. Buildings, structures, and parts thereof shall be designed to resist the effects of live loads.

    TABLE 1607.1—MINIMUM UNIFORMLY DISTRIBUTED LIVE LOADS, L, AND MINIMUM CONCENTRATED LIVE LOADS
    0    		 Col2 Col3 Col4 Col5 Col6
    OCCUPANCY OR USE OCCUPANCY OR USE OCCUPANCY OR USE UNIFORM
    (psf)    		 CONCENTRATE
    D (pounds)    		 ALSO SEE
    SECTION
    1. Apartments (see residential) Apartments (see residential) — — —
    2. Access floor systems Office use 50 2,000 —
    2. Access floor systems Computer use 100 2,000 —
    3. Armories and drill rooms Armories and drill rooms 150a — —
    4. Assembly areas Fixed seats (fastened to floor) 60a — —
    4. Assembly areas Lobbies 100a
    4. Assembly areas Movable seats 100a
    4. Assembly areas Stage floors 150a
    4. Assembly areas Platforms (assembly) 100a
    4. Assembly areas Bleachers, folding and telescopic seat-
    ing and grandstands    		 100a (See Section 1607.18)
    4. Assembly areas Stadiums and arenas with fixed seats
    (fastened to the floor)    		 60a (See Section 1607.18)
    4. Assembly areas Other assembly areas 100a
    5. Balconies and decks Balconies and decks 1.5 times the live load for the area
    served, not required to exceed 100    		 — —
    6. Catwalks for maintenance and service access Catwalks for maintenance and service access 40 300 —
    7. Cornices Cornices 60 — —
    8. Corridors First floor 100 — —
    8. Corridors Other floors Same as occupancy
    served except as indicated    		 Same as occupancy
    served except as indicated    		 Same as occupancy
    served except as indicated
    9. Dining rooms and restaurants Dining rooms and restaurants 100a — —
    10. Dwellings (see residential) Dwellings (see residential) — — —
    11. Elevator machine room and control room grating
    (on area of 2 inches by 2 inches)    		 Elevator machine room and control room grating
    (on area of 2 inches by 2 inches)    		 — 300 —
    12. Finish light floor plate construction (on area of 1 inch by 1 inch) Finish light floor plate construction (on area of 1 inch by 1 inch) — 200 —
    13. Fire escapes Fire escapes 100 — —
    13. On single-family dwellings only 40 40 40
    14. Fixed ladders Fixed ladders See Section 1607.10 See Section 1607.10 —
    15.
  • CBC § 903.2.5 Medium relevance — show source text

    903.2.5

    Ventilation 414.3, 415.9.1.7, 415.11.1.6, 415.11.1.8.1, 415.11.3.2, 415.11.6.8, 415.11.7.4, 415.11.8, 415.11.11, 1202.6 Weather protection 414.6.1 Hazardous Occupancy (Group H), (see Hazardous Materials) 307, 414, 415 Alarms and detection 415.11.2, 415.11.4, 415.11.6.9, 415.11.8, 415.3, 415.5, 907.2.5, 908.1, 908.2 Area 503, 505, 506, 507, 508 Dispersing 414.5, 414.6, 415.6 Gas detection systems 415.11.7 Group provisions H-1 (detonation) 307.3, 415.6.2, 415.7, 415.6.4.1, 415.7.1 H-2 (deflagration) 307.4, 415.8, 415.9 H-3 (physical hazard) 415.10, 307.5, 415.8 H-4 (health hazard) 307.6, 415.10 H-5 (semiconductor) 307.7, 415.11 Height 415.7, 415.8.1, 415.9.1.1, 426.1.1, 503, 504, 505, 506 Incidental uses 509

    Interior finishes 416.2.1, 416.3.1, Table 803.13, 804 Live load Table 1607.1

    Location on property 414.6.1.2, 415.6 Low hazard 306.3, 311.3 Means of egress Corridors 415.11.2 One means of egress Table 1006.3.4(1), Table 1006.3.4(2) Panic hardware 1006.2.2.2, 1006.2.2.3, 1006.2.2.4, 1010.2.8 Stairway, exit access 1019 Travel distance 1006.3, 1006.2.1, Table 1017.2

    Mixed occupancies 508.3, 508.4 Accessory 508.2 Moderate hazard 306.2, 311.2 Multiple hazards 306.2, 311.2 Occupancy exceptions 307.1 Plumbing fixtures Chapter 29 Risk category Table 1604.5 Separation from other occupancies 415.6.1, 508.1, 508.2.4, 508.3.3, 508.4 Smoke and heat removal 910.2 Special provisions based on materials Combustible liquids Table 307.1(1), 307.4, 307.5, 414.2.5, 414.5.3,

    415.9.2

    Corrosives 307.6, Table 414.2.5.1, 414.3, 415.10.3, Table 415.11.1.1 Explosives 307.3, 307.3.1, Table 415.6.5

  • CBC § 101.4.7 Medium relevance — show source text

    Existing 101.4.7 Fire walls 706.1 Height (see Height, Building) 502.1, 503, 504, 505, 508, 510 Occupancy classification Chapter 3 Party walls 706.1.1 Relocatable 3113

    Replicable Appendix N Building, Existing 202 Building Department 103 Building Official Duties and powers 103, 104 Qualifications Appendix A Records 104.7

    Termination A101.4 Building-Integrated Photovoltaic (BIPV) (see Photovoltaic) Built-Up Roof 1507.10 Business Occupancy (Group B) 303.1.1, 303.1.2, 304 Alarms and detection 907.2.2 Ambulatory care facilities 304, 422 Area 503, 505, 506, 507, 508 Height 503, 504, 505, 508, 510 Higher education laboratories 428, 2702.2

    Incidental uses 509 Interior finishes Table 803.13, 804 Live load Table 1607.1 Means of egress Aisles 1018.3

    Stairway, exit access 1019 Travel distance 1006.3, 1017.2,

    1006.2.1

    Mixed occupancies 508.2, 508.3, 508.4 Accessory 303.1.2, 508.2 Ambulatory care facilities 422 Assembly 303.1.2

    Assembly spaces 1030 Exit signs 1013.1 Guards 1015.2, 1030.17 Main exit 1030.3

    Open air 1005.3.1, 1005.3.2, 1006.3, 1009.6.4, 1019.3, 1027, 1030.6.2 Panic hardware 1010.2.8, 1010.4.1 Smoke-protected 1005.3.1, 1005.3.2, 1006.3, 1009.6.4, 1019.3, 1027, 1030.6.2 Travel distance 1006.2.1, 1006.3, 1017.2, 1030.7 Mixed occupancies 508.3, 508.4 Accessory 508.2 Education 303.1.3

  • CBC § 202.3. Medium relevance — show source text
    1. Residential dwelling units not required to be accessible in compliance with this code shall not be required to comply with Section 11B- 202.3.

    11B- 202.3.1 Prohibited reduction in access. An alteration that decreases or has the effect of decreasing the accessibility of a building or facility below the requirements for new construction at the time of the alteration is prohibited.

    11B- 202.3.2 Extent of application. An alteration of an existing element, space or area of a building or facility shall not impose a requirement for accessibility greater than required for new construction.

    11B-202.3.3 Alteration of single elements. If alterations of single elements, when considered together, amount to an alteration of a room or space in a building or facility, the entire room or space shall be made accessible.

    11B- 202.4 Path of travel requirements in alterations, additions and structural repairs. When alterations or additions are made to existing buildings or facilities, an accessible path of travel to the specific area of alteration or addition shall be provided. The primary accessible path of travel shall include:

    1. A primary entrance to the building or facility, 2. Toilet and bathing facilities serving the area, 3. Drinking fountains serving the area,

    4. Public telephones serving the area, and

    5. Signs.

    Exceptions:

    1. Residential dwelling units shall comply with Section 11B-233.3.4.2. 2. If the following elements of a path of travel have been constructed or altered in compliance with the accessibility require- ments of the immediately preceding edition of the California Building Code, it shall not be required to retrofit such elements to reflect the incremental changes in this code solely because of an alteration to an area served by those elements of the path of travel:

    1. A primary entrance to the building or facility, 2. Toilet and bathing facilities serving the area, 3. Drinking fountains serving the area,

    4. Public telephones serving the area, and

    11B-8 2025 CALIFORNIA BUILDING CODE

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    ACCESSIBILITY TO PUBLIC BUILDINGS, PUBLIC ACCOMMODATIONS, COMMERCIAL BUILDINGS AND PUBLIC HOUSING

    5. Signs.

    Note: The language in this exception, which refers to the “immediately preceding edition of the California Building Code,” shall permit a reference back to one CBC edition only and is not accumulative to prior editions. 3. Additions or alterations to meet accessibility requirements consisting of one or more of the following items shall be limited to the actual scope of work of the project and shall not be required to comply with Section 11B-202.4: 1. Altering one building entrance. 2. Altering one existing toilet facility. 3. Altering existing elevators. 4. Altering existing steps. 5. Altering existing handrails. 4. Alterations solely for the purpose of barrier removal undertaken pursuant to the requirements of the Americans with Disabil- _ities Act (Public Law 101-336, 28 C.F.R. Section 36.

  • CBC § 508.5.8 High relevance — show source text

    508.5.8 Structural. Floors within a live/work unit shall be designed for the live loads in Table 1607.1, based on the function within the space.

    Exception: Residential areas of live/work units constructed in accordance with the California Residential Code shall not be required to comply with Table 1607.1.

    [BE] 508.5.9 Accessibility. Accessibility shall be designed in accordance with Chapter 11A and/or 11B, when applicable, for the function served.

    508.5.10 Ventilation. The applicable ventilation requirements of the California Mechanical Code shall apply to each area within the live/work unit for the function within that space.

    508.5.11 Plumbing facilities. The nonresidential area of the live/work unit shall be provided with minimum plumbing facilities as specified by the California Plumbing Code, based on the function of the nonresidential area. Where the nonresidential area of the live/work unit is required to be accessible, the plumbing fixtures specified by the California Plumbing Code shall be accessible.

    SECTION 509—INCIDENTAL USES

    509.1 General Incidental uses located within single occupancy or mixed occupancy buildings shall comply with the provisions of this section. Incidental uses are ancillary functions associated with a given occupancy that generally pose a greater level of risk to that occupancy and are limited to those uses specified in Table 509.1.

    Exception: Incidental uses within and serving a dwelling unit are not required to comply with this section.

    �

    [F] TABLE 509.1—INCIDENTAL USES Col2
    ROOM OR AREA SEPARATION AND/OR PROTECTION
    Furnace room where any piece of equipment is over 400,000 Btu per
    hour input    		 1 hour or provide automatic sprinkler system
    Rooms with boilers where the largest piece of equipment is over 15 psi
    and 10 horsepower    		 1 hour or provide automatic sprinkler system
    Refrigerant machinery room 1 hour or provide automatic sprinkler system
    Hydrogen fuel gas rooms, not classified as Group H 1 hour in Group B, F, M, S and U occupancies; 2 hours in Group A, E, I
    and R occupancies.
    Incinerator rooms 2 hours and provide automatic sprinkler system
    Paint shops, not classified as Group H, located in occupancies other
    than Group F    		 2 hours; or 1 hour and provide automatic sprinkler system
    In Group E occupancies, laboratories and vocational shops not classi-
    fied as Group H    		 1 hour or provide automatic sprinkler system
    [SFM]Rooms or areas with special hazards such as laboratories, voca-
    tional shops and other such areas not classified as Group H, located in
    Group E occupancies where hazardous materials in quantities not
    exceeding the maximum allowable quantity are used or stored.    		 1 hour
    In Group I-2 occupancies, laboratories not classified as Group H 1 hour_a_
    In ambulatory care facilities, laboratories not classified as Group H 1 hour or provide automatic sprinkler system
    Laundry rooms over 100 square feet 1 hour or provide automatic sprinkler system
    In Group I-2, laundry rooms over 100 square feet 1 hour and provide automatic sprinkler system_a_
    Group I-3 cells and Group I-2 patient rooms equipped with padded
    surfaces    		 1 hour and provide automatic sprinkler system_a_
    In Group I-2,
  • CBC § 1006.2.2.1 High relevance — show source text

    Exits 1006.2.2.1

    Bolts

    Anchor rods 1901.3 Bonding, Masonry 1805.2.2, 2103.2.2, 2113.3.1, 2510.7 Bottle-Filling Stations 202 Braced Wall Line 202

    Bracing 2308.10 Seismic requirements 2308.10.10.2, 2308.10.6.2, 2308.10.8 Sill anchorage 2308.10.7.3 Spacing 2308.10.1 Support 2308.10.8 Temporary 3103.5 Braced Wall Panel 202 Alternative bracing 2308.10.5.1, 2308.10.5.2

    Connections 2308.10.7 Length 2308.10.4 Location 2308.10.2

    Method 2308.10.3 Brick (see Masonry) Building Area (see Area, Building) 502.1, 503, 505, 506, 507, 508, 510 Demolition 3303

    Existing 101.4.7 Fire walls 706.1 Height (see Height, Building) 502.1, 503, 504, 505, 508, 510 Occupancy classification Chapter 3 Party walls 706.1.1 Relocatable 3113

    Replicable Appendix N Building, Existing 202 Building Department 103 Building Official Duties and powers 103, 104 Qualifications Appendix A Records 104.7

    Termination A101.4 Building-Integrated Photovoltaic (BIPV) (see Photovoltaic) Built-Up Roof 1507.10 Business Occupancy (Group B) 303.1.1, 303.1.2, 304 Alarms and detection 907.2.2 Ambulatory care facilities 304, 422 Area 503, 505, 506, 507, 508 Height 503, 504, 505, 508, 510 Higher education laboratories 428, 2702.2

    Incidental uses 509 Interior finishes Table 803.13, 804 Live load Table 1607.1 Means of egress Aisles 1018.3

    Stairway, exit access 1019 Travel distance 1006.3, 1017.2,

    1006.2.1

    Mixed occupancies 508.2, 508.3, 508.4 Accessory 303.1.2, 508.2 Ambulatory care facilities 422 Assembly 303.1.2

    Assembly spaces 1030 Exit signs 1013.1 Guards 1015.2, 1030.17 Main exit 1030.3

  • CBC § 407.2.3 High relevance — show source text

    In detention or secure mental health facilities, the provisions above applies to enclosed nurse stations within the corridor.

    407.2.3 Psychiatric treatment areas. Areas wherein psychiatric care recipients who are incapable of self-preservation are housed, or group meeting or multipurpose therapeutic spaces other than incidental uses in accordance with Section 509, under continuous supervision by facility staff, shall be permitted to be open to the corridor, where the following criteria are met:

    1. Each area does not exceed 1,500 square feet (140 m [2] ).
    2. The area is located to permit supervision by the facility staff.
    3. The area is arranged so as not to obstruct any access to the required exits.
    4. The area is equipped with an automatic fire detection system installed in accordance with Section 907.2.
    5. Not more than one such space is permitted in any one smoke compartment.
    6. The walls and ceilings of the space are constructed as required for corridors. 407.2.4 Gift shops. Gift shops and associated storage that are less than 500 square feet (455 m [2] ) in area shall be permitted to be open to the corridor where such spaces are constructed as required for corridors.

    407.2.5 Nursing home housing units. In Group I-2, Condition 1 occupancies, in areas where nursing home residents are housed, shared living spaces, group meeting or multipurpose therapeutic spaces shall be permitted to be open to the corridor, where all of the following criteria are met:

    1. The walls and ceilings of the space are constructed as required for corridors.

    2. The spaces are not occupied as resident sleeping rooms, treatment rooms, incidental uses in accordance with Section 509, or hazardous uses.

    3. The open space is protected by an automatic smoke detection system installed in accordance with Section 907.

    4. The corridors onto which the spaces open, in the same smoke compartment, are protected by an automatic smoke detection system installed in accordance with Section 907, and the smoke compartment in which the spaces are located is equipped throughout with quick-response sprinklers in accordance with Section 903.3.2.

    5. The space is arranged so as not to obstruct access to the required exits. 6. Each space is located to permit direct visual supervision by the facility staff.

    407.2.6 Nursing home cooking facilities. In Group I-2, Condition 1 occupancies, rooms or spaces that contain a cooking facility with domestic cooking appliances shall be permitted in fully sprinklered buildings where all of the following criteria are met:

    1. The number of care recipients housed in the smoke compartment shall not be greater than 30.
    2. The number of care recipients served by the cooking facility shall not be greater than 30.
    3. Only one cooking facility area shall be permitted in a smoke compartment.
    4. The corridor shall be a clearly identified space delineated by construction or floor pattern, material or color.
    5. The space containing the domestic cooking facility shall be arranged so as not to obstruct access to the required exit.
    6. The cooking appliance shall comply with Section 407.2.7.
  • CBC § 1009.1 High relevance — show source text

    1009.1 Moving walk 1003.7 Number 1001.2, 1006 Occupant load 1004 Parking 406.5.7 Protruding objects 1003.3, 1005.7 Ramps 1012, 1019, 1027 Scoping 101.3, 108.2, 1001.1 Seating, fixed 1009.1, 1030 Special amusement areas 411.4 Stages 410.2.3, 410.5 Stairways 403.5, 404.6, 1005.3.1, 1011, 1019, 1023, 1027 Temporary structures 3103.4 Travel distance (see Travel Distance) 1006.2.1,

    1017

    Turnstile 1010.5

    Underground buildings 405.5.1, 405.7 Width 1005.1, 1005.2, 1005.4, 1011.2, 1012.5.1, 1020.3, 1030.6, 1030.8 Mechanical (see Air Conditioning, Heating, Refrigeration and Ventilation) 101.4.2 Access 1011.12, 1208.4 Air transfer openings 705.11, 706.11, 707.10, 708.9, 709.8, 712.1.6, 713.10, 714.1.1, 717 Chimneys (see Chimneys) Code Chapter 28 Disconnected 3303.6

    Ducts 704.7, 705.11, 706.11, 707.10, 708.9, 709.8, 710.8, 712.1.10.3, 712.1.6, 713.10, 714.1.1, 717 Encroachment, public right-of-way 3202.3.2 Equipment on roof 1511 Equipment platforms 505.3 Fireplaces 2111 Incidental use room Table 509.1

    Motion picture projection room 409.3 Permit required 105.1, 105.2 Roof access 1011.12 Seismic inspection and testing 1704.3.2, 1705.13.7 Smoke control system 909 Systems Chapter 28 Mechanically Laminated Decking 2304.9.3 Medical Care (see Institutional I-2) 407.1 Medical Gas Systems 427 Membrane Roof Coverings 1507.11, 1507.12, 1507.13 Membrane Structures 2702.2, 3102 Mercantile Occupancy (Group M) 309 Accessible Chapter 11B Alarm and detection 907.2.6.3.4

    Area 503, 505, 506, 507, 508 Covered and open mall buildings 402 Hazardous material display and storage 414.2.5 Height 503, 504, 505, 508 Incidental uses 509

Frequently asked questions

What exactly is an "incidental use"?

An incidental use is a specific ancillary room or area listed in Table 509.1 that presents higher risk than the surrounding occupancy and therefore requires rated separation or other protection per § 509.1 and Table 509.1.

Can I avoid rated walls by adding sprinklers?

For many Table 509.1 entries you may choose the sprinkler alternative instead of rated separations; confirm the sprinkler system meets Chapter 9 requirements before relying on that option. See Table 509.1 and Chapter 9.

Do these rules apply to incidental rooms inside an apartment?

No — incidental uses located within and serving a dwelling unit are exempt from Section 509 as stated in § 509.1.

If a room is borderline (e.g., laundry = 100 sq ft), how is it treated?

Table 509.1 uses the numeric thresholds shown in the table (e.g., laundries over 100 sq ft). If the area equals the threshold, follow the exact table wording and consult the full CBC table/footnotes for clarification.

Are there construction‑type exceptions for incidental separations?

Yes — in Types IIB, IIIB, and VB the supporting construction for horizontal assemblies at incidental separations is not required to be fire‑resistance rated when the required rating does not exceed 1 hour (see § 711.2.3).

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