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Earlier editions: 20222019

Chapter 1 — GENERAL CODE PROVISIONS

102.1 Conflicts Between Codes. Where the requirements

California Mechanical Code (Title 24, Part 4) · 2025 edition · updated 2026-09-10 · California

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

within the jurisdiction of this mechanical code conflict with the requirements of the plumbing code, the plumbing code shall prevail. In instances where this code, applicable standards, or the manufacturer’s installation instructions conflict, the more stringent provisions shall prevail. Where there is a conflict between a general requirement and a specific requirement, the specific requirement shall prevail. [OSHPD 1, 1R, 2, 3, 4 & 5] See Chapter 1, Division I, Section 1.1.7

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▸Contents — California Mechanical Code (Title 24, Part 4)
California Mechanical Code (Title 24, Part 4)
  1. ▸Chapter 1 — GENERAL CODE PROVISIONS
    Overview
    1. 301.7 OSHPD 1R . . . . . . . . . . . . . . . . . . . 51
    2. 306.2 Building Automation Systems . . . . 56
    3. 311.5 California Energy Code
    4. 318.1 Applicability . . . . . . . . . . . . . . . . . . 60
    5. 318.2 Services/Systems and Utilities . . . . 60
    6. 319.1 Requirements for Hospitals and
    7. 319.2 Requirements for Skilled
    8. 320.1 Requirements for Hospitals and
    9. 320.2 Requirements for Skilled
    10. 320.3 Requirements for Outpatient
    11. 320.4 Telephone and Technology
    12. 320.5 Psychiatric Services. . . . . . . . . . . . 61
    13. 401.3 Filters . . . . . . . . . . . . . . . . . . . . . . . 69
    14. 407.1 General. . . . . . . . . . . . . . . . . . . . . . 78
    15. 407.2 Outdoor Air Intakes and
    16. 407.3 Air Balance. . . . . . . . . . . . . . . . . . . 78
    17. 407.4 Air Circulation . . . . . . . . . . . . . . . . . 78
    18. 407.5 Variable Air Volume . . . . . . . . . . . . 79
    19. 407.6 Economizers. . . . . . . . . . . . . . . . . . 79
    20. 407.7 Unoccupied Turndown. . . . . . . . . . 79
    21. 407.8 Building Pressurization . . . . . . . . . 80
    22. 408.1 General. . . . . . . . . . . . . . . . . . . . . . 80
    23. 408.2 Filters for Hospitals. . . . . . . . . . . . . 80
    24. 408.3 Filters for Skilled Nursing
    25. 408.4 Filters for Outpatient Facilities . . . . 80
    26. 408.5 Filters for Recirculating
    27. 410.1 Laboratory Ventilating Systems . . . 80
    28. 410.2 Exhaust Hoods and
    29. 410.3 Laboratory Fume Hoods . . . . . . . . 80
    30. 414.1 Exhaust Systems . . . . . . . . . . . . . . 81
    31. 414.2 Air Distribution . . . . . . . . . . . . . . . . 81
    32. 415.1 Air Distribution . . . . . . . . . . . . . . . . 82
    33. 418.1 Air Changes . . . . . . . . . . . . . . . . . . 82
    34. 418.2 Exhaust Requirements . . . . . . . . . . 82
    35. 418.3 Ventilation Requirements . . . . . . . . 82
    36. 418.4 Gas Valves . . . . . . . . . . . . . . . . . . . 82
    37. 418.5 Alarm Systems . . . . . . . . . . . . . . . . 83
    38. 419.1 Formula Preparation Area . . . . . . . 83
    39. 419.2 Treatment Area/Room . . . . . . . . . . 83
    40. 505.12 Pharmacies – Compounding
    41. 507.7 Pharmaceutical Compounding
    42. 609.2 Air-Moving Systems and
    43. 1602.2 Liquid-Fueled Engines and
    44. 104.2 Items (1) through (5) of this code.
    45. 101.1 Title. This document shall be known as the “Uniform
    46. 101.2 Scope. The provisions of this code shall apply to the
    47. 101.3 Purpose. This code is an ordinance providing minimum req…
    48. 101.4 Unconstitutional. Where a section, subsection, sentence,…
    49. 101.5 Validity. Where a provision of this code, or the applica…
    50. 102.1 Conflicts Between Codes. Where the requirements
    51. 102.2 Existing Installations. Mechanical systems lawfully
    52. 102.3 Maintenance. Mechanical systems, materials, and
    53. 102.4 Additions, Alterations, Renovations, or
    54. 102.5 Health and Safety. Where compliance with the provisions …
    55. 102.6 Changes in Building Occupancy. Mechanical
    56. 102.7 Moved Structures. Parts of the mechanical system of
    57. 102.8 Appendices. The provisions in the appendices are
    58. 103.1 General. The Authority Having Jurisdiction shall be
    59. 103.2 Liability. The Authority Having Jurisdiction charged
    60. 103.3 Applications and Permits. The Authority Having
    61. 103.4 Right of Entry. Where it is necessary to make an
    62. 104.1 Permits Required. It shall be unlawful for a person,
    63. 104.2 Exempt Work. A permit shall not be required for the
    64. 104.3 Application for Permit. To obtain a permit, the
    65. 104.4 Permit Issuance. The application, construction documents…
    66. 104.5 Fees. Fees shall be assessed in accordance with the
    67. 105.1 General. Mechanical systems for which a permit is
    68. 105.2 Required Inspections. New mechanical system
    69. 105.3 Testing of Systems. Mechanical systems shall be
    70. 105.4 Connection to Service Utilities. No person shall
    71. 106.1 General. It shall be unlawful for a person, firm, or
    72. 106.2 Notices of Correction or Violation. Notices of
    73. 106.3 Penalties. A person, firm, or corporation violating a
    74. 106.4 Stop Orders. Where work is being done contrary to
    75. 106.5 Authority to Disconnect Utilities in Emergen-
    76. 106.6 Authority to Condemn. Where the Authority Having Jurisdi…
    77. 107.1 General. In order to hear and decide appeals of orders,
    78. 107.2 Limitations of Authority. The Board of Appeals
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GENERAL REGULATIONS
  4. Chapter 4 — VENTILATION AIR
  5. Chapter 5 — EXHAUST SYSTEMS
  6. Chapter 6 — DUCT SYSTEMS
  7. Chapter 7 — COMBUSTION AIR
  8. Chapter 8 — CHIMNEYS AND VENTS
  9. Chapter 9 — INSTALLATION OF SPECIFIC APPLIANCES
  10. Chapter 10 — BOILERS AND PRESSURE VESSELS
  11. Chapter 11 — REFRIGERATION
  12. Chapter 12 — HYDRONICS
  13. Chapter 13 — FUEL GAS PIPING
  14. Chapter 14 — PROCESS PIPING
  15. Chapter 15 — SOLAR ENERGY SYSTEMS
  16. Chapter 16 — STATIONARY POWER PLANTS
  17. Chapter 17 — GEOTHERMAL ENERGY SYSTEMS AND AMBIENT TEMPERATURE…
  18. Chapter 18 — REFERENCED STANDARDS
  19. Appendix A — RESIDENTIAL PLAN EXAMINER REVIEW FORM FOR HVAC SY…
  20. Appendix B — PROCEDURES TO BE FOLLOWED TO PLACE GAS EQUIPMENT …
  21. Appendix C — INSTALLATION AND TESTING OF OIL (LIQUID) FUEL-FIR…
  22. Appendix D — FUEL SUPPLY: MANUFACTURED/MOBILE HOME PARKS AND R…
  23. Appendix E — SUSTAINABLE PRACTICES
  24. Appendix F — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION …
  25. Appendix G — EXAMPLE CALCULATION OF OUTDOOR AIR RATE
  26. Appendix H — PROFESSIONAL QUALIFICATIONS
  27. Appendix I — INDOOR HORTICULTURAL FACILITIES
  28. Appendix J — CLEAN AIR DELIVERY

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