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Chapter 5 — GENERAL BUILDING HEIGHTS AND AREAS

Section 509

California Building Code (Title 24, Part 2) · 2019 edition · updated 2026-09-12 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

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 func

tions associated with a given occupancy that generally pose a greater level of risk to that occupancy and are limited to those uses listed in Table 509.

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

509.2 Occupancy classification.

Incidental uses shall not be individually classified in accordance with Section 302.1. Incidental uses shall be included in the building occupancies within which they are located.

509.3 Area limitations.

The aggregate floor area of incidental uses shall not occupy more than 10 percent of the building area of the story in which they are located.

509.4 Separation and protection.

The incidental uses listed in Table 509 shall be separated from the remainder of the building or equipped with an automatic sprinkler system, or both, in accordance with the provisions of that table.

509.4.1 Separation. Where Table 509 specifies a fireresistance-rated separation, the incidental uses shall be separated from the remainder of the building by a fire barrier constructed in accordance with Section 707 or a horizontal assembly constructed in accordance with Section 711, or both. Construction supporting 1-hour fire barriers or horizontal assemblies used for incidental use separa

Copyright © 2019 ICC. ALL RIGHTS RESERVED. Accessed by Kevin Day (kevin.day@dgs.ca.gov), (California Building Standards Commission) Order Number #100735044 on Jul 24, 2019 03:54 PM (PDT) pursuant to License Agreement with ICC. No further reproduction or distribution authorized. Single user only, copying and networking prohibited. ANY UNAUTHORIZED REPRODUCTION OR DISTRIBUTION IS A VIOLATION OF THE FEDERAL COPYRIGHT ACT AND THE LICENSE AGREEMENT, AND SUBJECT TO CIVIL AND CRIMINAL PENALTIES THEREUNDER.

100735044

GENERAL BUILDING HEIGHTS AND AREAS

[F] TABLE 509 INCIDENTAL USES

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 classified as Group H 1 hour or provide automatic sprinkler system
[SFM]Rooms or areas with special hazards such as laboratories, vocational 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_and I-2.1_occupancies, laboratories not classified as Group H 1 hour and provide automatic sprinkler system_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_a_
In Group I-2, laundry rooms over 100 square feet 1 hour
Group I-3 cells and Group I-2_and I-2.1_patient rooms equipped with padded surfaces 1 hour
In Group I-2, physical plant maintenance shops 1 hour
In ambulatory care facilities or Group I-2_and I-2.1_occupancies, waste and linen collection
rooms with containers that have an aggregate volume of 10 cubic feet or greater		 1 hour_a_
In other than ambulatory care facilities and Group I-2_and I-2.1_occupancies, waste and
linen collection rooms over 100 square feet		 1 hour or provide automatic sprinkler system
In ambulatory care facilities or Group I-2_and I-2.1_occupancies, storage rooms greater than
100 square feet		 1 hour
Stationary storage battery systems having an energy capacity greater than the threshold
quantity specified in Table 1206.2 of the_California Fire Code_		 1 hour in Group B, F, M, S and U occupancies;
2 hours in Group A, E, I and R occupancies.a
Electrical installations and transformers See Sections 110.26 through 110.34 and
Sections 450.8 through 450.48 of the_California_
_Electrical Cod_e for protection and separation
requirements.

For SI: 1 square foot = 0.0929 m 2, 1 pound per square inch (psi) = 6.9 kPa, 1 British thermal unit (Btu) per hour = 0.293 watts,

1 horsepower = 746 watts, 1 gallon = 3.785 L, 1 cubic foot = 0.0283 m 3 . a. [SFM] Fire barrier protection and automatic sprinkler protection required throughout the fire area in I-2 and I-2.1 occupancies as indicated.

tions in buildings of Type IIB, IIIB and VB construction is not required to be fire-resistance rated unless required by other sections of this code.

509.4.2 Protection. Where Table 509 permits an automatic sprinkler system without a fire barrier, the incidental uses shall be separated from the remainder of the building by construction capable of resisting the passage of smoke. The walls shall extend from the top of the foundation or floor assembly below to the underside of the ceiling that is a component of a fire-resistance-rated floor assembly or roof assembly above or to the underside of the floor or roof sheathing, deck or slab above. Doors shall be self- or automatic-closing upon detection of smoke in accordance with Section 716.2.6.6. Doors shall not have air transfer openings and shall not be undercut in excess of the clearance permitted in accordance with NFPA 80. Walls surrounding the incidental use shall not have air transfer

openings unless provided with smoke dampers in accordance with Section 710.8.

509.4.2.1 Protection limitation. Where an automatic sprinkler system is provided in accordance with Table 509, only the space occupied by the incidental use need be equipped with such a system.

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▸Contents — California Building Code (Title 24, Part 2)
California Building Code (Title 24, Part 2)
  1. Chapter 2 — DEFINITIONS AND ABBREVIATIONS
  2. Appendix G — FLOOD-RESISTANT
  3. Appendix L — EARTHQUAKE RECORDING
  4. Appendix M — TSUNAMI-GENERATED
  5. Chapter 1 — SCOPE AND ADMINISTRATION
  6. Chapter 3 — OCCUPANCY CLASSIFICATION AND USE
  7. Chapter 4 — SPECIAL DETAILED REQUIREMENTS BASED
  8. ▸Chapter 5 — GENERAL BUILDING HEIGHTS AND AREAS
    Overview
    1. Section 501
    2. Section 502
    3. Section 503
    4. Section 504
    5. Section 505
    6. Section 506
    7. Section 507
    8. Section 508
    9. Section 509
    10. Section 510
  9. Chapter 6 — TYPES OF CONSTRUCTION
  10. Chapter 7 — FIRE AND SMOKE PROTECTION FEATURES
  11. Chapter 7A — MATERIALS AND CONSTRUCTION
  12. Chapter 8 — INTERIOR FINISHES
  13. Chapter 9 — FIRE PROTECTION AND LIFE SAFETY SYSTEMS
  14. Chapter 10 — MEANS OF EGRESS
  15. Chapter 11A — HOUSING ACCESSIBILITY
  16. Chapter 11B — ACCESSIBILITY TO PUBLIC BUILDINGS, PUBLIC ACCOMM…
  17. Chapter 12 — INTERIOR ENVIRONMENT
  18. Chapter 14 — EXTERIOR WALLS
  19. Chapter 15 — ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
  20. Chapter 16 — STRUCTURAL DESIGN
  21. Chapter 16A — STRUCTURAL DESIGN
  22. Chapter 17 — SPECIAL INSPECTIONS AND TESTS
  23. Chapter 18 — SOILS AND FOUNDATIONS
  24. Chapter 19 — CONCRETE
  25. Chapter 20 — ALUMINUM
  26. Chapter 21 — MASONRY
  27. Chapter 22 — STEEL
  28. Chapter 23 — WOOD
  29. Chapter 24 — GLASS AND GLAZING
  30. Chapter 25 — GYPSUM BOARD, GYPSUM PANEL PRODUCTS AND PLASTER
  31. Chapter 26 — PLASTIC
  32. Chapter 27 — ELECTRICAL
  33. Chapter 28 — MECHANICAL SYSTEMS
  34. Chapter 30 — ELEVATORS AND CONVEYING SYSTEMS
  35. Chapter 31 — SPECIAL CONSTRUCTION
  36. Chapter 31B — PUBLIC POOLS
  37. Chapter 31C — RADIATION
  38. Chapter 31D — FOOD ESTABLISHMENTS
  39. Chapter 31F — MARINE OIL TERMINALS
  40. Chapter 32 — ENCROACHMENTS INTO THE PUBLIC RIGHT-OF-WAY
  41. Chapter 33 — SAFEGUARDS DURING CONSTRUCTION
  42. Chapter 35 — REFERENCED STANDARDS
  43. Appendix A — EMPLOYEE QUALIFICATIONS
  44. Appendix B — BOARD OF APPEALS
  45. Appendix C — GROUP U – AGRICULTURAL BUILDINGS
  46. Appendix D — FIRE DISTRICTS
  47. Appendix F — RODENTPROOFING
  48. Appendix H — SIGNS
  49. Appendix I — PATIO COVERS
  50. Appendix J — GRADING
  51. Appendix K — GROUP R-3 AND GROUP R-3.1 OCCUPANCIES
  52. Appendix N — REPLICABLE BUILDINGS
  53. Appendix O — EMERGENCY HOUSING

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