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Chapter 4 — SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY AND USE

Section 421

California Building Code (Title 24, Part 2) · 2022 edition · updated 2026-09-12 · California

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

HYDROGEN FUEL GAS ROOMS

[F] 421.1 General. Where required by the California Fire Code, hydrogen fuel gas rooms shall be designed and constructed in accordance with Sections 421.1 through 421.7.

[F] 421.2 Location. Hydrogen fuel gas rooms shall not be located below grade.

[F] 421.3 Design and construction. Hydrogen fuel gas rooms not classified as Group H shall be separated from other areas of the building in accordance with Section 509.1.

[F] 421.3.1 Pressure control. Hydrogen fuel gas rooms shall be provided with a ventilation system designed to maintain the room at a negative pressure in relation to surrounding rooms and spaces.

[F] 421.3.2 Windows. Operable windows in interior walls shall not be permitted. Fixed windows shall be permitted where in accordance with Section 716.

[F] 421.4 Exhaust ventilation. Hydrogen fuel gas rooms shall be provided with mechanical exhaust ventilation in accordance with the applicable provisions of Section 502.16.1 of the California Mechanical Code .

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. 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.

SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY AND USE

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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. Appendix N — REPLICABLE
  6. Appendix O — PERFORMANCE-BASED
  7. Chapter 1 — SCOPE AND ADMINISTRATION
  8. Chapter 3 — OCCUPANCY CLASSIFICATION AND USE
  9. ▸Chapter 4 — SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY A…
    Overview
    1. Section 401
    2. Section 402
    3. Section 403
    4. Section 404
    5. Section 405
    6. Section 406
    7. Section 407
    8. Section 408
    9. Section 409
    10. Section 410
    11. Section 412
    12. Section 411
    13. Section 413
    14. Section 414
    15. Section 415
    16. Section 416
    17. Section 417
    18. Section 418
    19. Section 419
    20. Section 420
    21. Section 422
    22. Section 421
    23. Section 423
    24. Section 424
    25. Section 425
    26. Section 427
    27. Section 435
    28. Section 436
    29. Section 437
    30. Section 438
    31. Section 440
    32. Section 441
    33. Section 442
    34. Section 443
    35. Section 444
    36. Section 445
    37. Section 446
    38. Section 447
    39. Section 448
    40. Section 449
    41. Section 450
    42. Section 451
    43. Section 452
    44. Section 453
    45. Section 454
    46. Section 455
  10. Chapter 5 — GENERAL BUILDING HEIGHTS AND AREAS
  11. Chapter 6 — TYPES OF CONSTRUCTION
  12. Chapter 7 — FIRE AND SMOKE PROTECTION FEATURES
  13. Chapter 7A — MATERIALS AND CONSTRUCTION
  14. Chapter 8 — INTERIOR FINISHES
  15. Chapter 9 — FIRE PROTECTION AND LIFE SAFETY SYSTEMS
  16. Chapter 10 — MEANS OF EGRESS
  17. Chapter 11A — HOUSING ACCESSIBILITY
  18. Chapter 11B — ACCESSIBILITY TO PUBLIC BUILDINGS, PUBLIC ACCOMM…
  19. Chapter 12 — INTERIOR ENVIRONMENT
  20. Chapter 14 — EXTERIOR WALLS
  21. Chapter 15 — ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
  22. Chapter 16 — STRUCTURAL DESIGN
  23. Chapter 16A — STRUCTURAL DESIGN
  24. Chapter 17 — SPECIAL INSPECTIONS AND TESTS
  25. Chapter 18 — SOILS AND FOUNDATIONS
  26. Chapter 19 — CONCRETE
  27. Chapter 20 — ALUMINUM
  28. Chapter 21 — MASONRY
  29. Chapter 22 — STEEL
  30. Chapter 23 — WOOD
  31. Chapter 24 — GLASS AND GLAZING
  32. Chapter 25 — GYPSUM BOARD, GYPSUM PANEL PRODUCTS AND PLASTER
  33. Chapter 26 — PLASTIC
  34. Chapter 27 — ELECTRICAL
  35. Chapter 28 — MECHANICAL SYSTEMS
  36. Chapter 30 — ELEVATORS AND CONVEYING SYSTEMS
  37. Chapter 31 — SPECIAL CONSTRUCTION
  38. Chapter 31B — PUBLIC POOLS
  39. Chapter 31C — RADIATION
  40. Chapter 31D — FOOD ESTABLISHMENTS
  41. Chapter 31F — MARINE OIL TERMINALS
  42. Chapter 32 — ENCROACHMENTS INTO THE PUBLIC RIGHT-OF-WAY
  43. Chapter 33 — SAFEGUARDS DURING CONSTRUCTION
  44. Chapter 35 — REFERENCED STANDARDS
  45. Appendix A — EMPLOYEE QUALIFICATIONS
  46. Appendix B — BOARD OF APPEALS
  47. Appendix C — GROUP U – AGRICULTURAL BUILDINGS
  48. Appendix D — FIRE DISTRICTS
  49. Appendix F — RODENTPROOFING
  50. Appendix H — SIGNS
  51. Appendix I — PATIO COVERS
  52. Appendix J — GRADING
  53. Appendix K — GROUP R-3 AND GROUP R-3.1 OCCUPANCIES
  54. Appendix P — EMERGENCY HOUSING

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