Skip to content

Chapter 6 — DUCT SYSTEMS

California Mechanical Code (Title 24, Part 4) · 2019 edition · updated 2026-09-10 · California

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

(Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

Adopting Agency BSC BSC-
CG		 SFM HCD DSA OSHPD BSCC DPH AGR DWR CEC CA SL SLC
Adopting Agency
 **BSC **
 BSC-
CG		 SFM 1 2 1-AC **AC ** SS SS/CC 1 1R 2 3 4 5 5 5 5 5 5 5 5 5
Adopt Entire Chapter

 X

Adopt Entire Chapter as
amended (amended sections
listed below)
 X **X ** X X X **X ** **X ** **X ** **X ** **X ** X

Adopt only those sections
that are listed below

Chapter/Section
601.2,~~~~Exception
 **X ** X

602.1

**X ** **X ** **X ** **X ** **X ** X
602.2.1
 **X ** X





602.1,~~~~Exception
 **X **
 **X **
 **X **
 **X **
 **X **
 X

602.6.1
**X **
**X **
**X **
**X **
**X **
X
603.3.3
 **X ** X





603.4.1

**X ** **X ** **X ** **X ** **X ** X
603.10.1
 **† **
 †
603.10.1.1
**X **
X
604.1
 **X **
 **X **
 **X **
 **X **
 **X **
 X
604.2
**X **
**X **
**X **
**X **
**X **
X
604.3
**X **
**X **
X
**X **
X
605.1
 **X ** X
605.8
 X

X X
606.1
 **X ** X
606.1.1
 **X ** **X ** **X ** **X ** **X ** X


608.1
X
X
X

The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.

2019 CALIFORNIA MECHANICAL CODE 119

120 2019 CALIFORNIA MECHANICAL CODE

CHAPTER 6

DUCT SYSTEMS

601.0 General.601.1 Applicability. Ducts and plenums that are portions of

a heating, cooling, ventilation, or exhaust system shall comply with the requirements of this chapter.

605.0 Smoke Dampers, Fire Dampers, and Ceiling

607.0 Use of Under-Floor Space as Supply Plenum

Get a plain-English answer with a citation back to this text.

Ask AI about this code
Export this section
▸Contents — California Mechanical Code (Title 24, Part 4)
California Mechanical Code (Title 24, Part 4)
  1. Chapter 1 — GENERAL CODE PROVISIONS
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GENERAL REGULATIONS
  4. Chapter 4 — VENTILATION AIR
  5. Chapter 5 — EXHAUST SYSTEMS
  6. ▸Chapter 6 — DUCT SYSTEMS
    Overview
    1. 601.2 Sizing Requirements. Duct systems shall be sized in
    2. 602.1 General. 602.0 Material. Materials used for duct systems…
    3. 602.2 Combustibles Within Ducts or Plenums. Materials exposed …
    4. 602.3 Metal. Ducts, plenums, or fittings of metal shall comply…
    5. 602.4 Phenolic. Ducts, plenums, or fittings of phenolic shall
    6. 602.5 Gypsum. Where gypsum products are exposed in ducts
    7. 602.6 Factory-Made Air Ducts. Factory-made air ducts
    8. 602.7 Vibration Isolators. Vibration isolation connectors
    9. 602.8 Corridors. Corridors shall not be used to convey air to
    10. 603.4 Factory-Made Air Ducts. Factory-made air ducts shall
    11. 603.1 General.603.0 Installation of Ducts. The pressure classi…
    12. 603.2 Under Floor or Crawl Space. Air ducts installed
    13. 603.3 Metal Ducts. Ducts shall be supported at each change
    14. 603.5 Flexible Air Ducts. Flexible air ducts shall comply
    15. 603.6 Plastic Ducts. Plastic air ducts and fittings shall be
    16. 603.7 Protection of Ducts. Ducts installed in locations
    17. 603.8 Support of Ducts. Installers shall provide the manufactu…
    18. 603.9 Protection Against Flood Damage. In flood hazard areas, …
    19. 603.10 Joints and Seams of Ducts. Joints and seams for
    20. 603.11 Cross Contamination. Exhaust ducts and venting
    21. 603.12 Underground Installation. Ducts installed underground s…
    22. 603.13 Air Dispersion Systems. Where installed, air dispersion…
    23. 604.0 Insulation of Ducts.604.1 General. Air ducts conveying a…
    24. 604.2 [OSHPD 1, 1R, 2, 3 (surgical clinics), 4 & 5] Ther-
    25. 604.3 [OSHPD 1, 1R, 2, 4 & 5] Thermal or acoustical lining
    26. 605.1 Smoke Dampers.Dampers. Smoke dampers shall comply with
    27. 605.2 Fire Dampers. Fire dampers shall comply with UL
    28. 605.3 Ceiling Radiation Dampers. Ceiling radiation
    29. 605.4 Multiple Arrangements. Where size requires the
    30. 605.5 Access and Identification. Fire and smoke dampers
    31. 605.6 Freedom from Interference. Dampers shall be
    32. 605.8 When the automatic activation of a smoke damper or a
    33. 606.1 General. 606.0 Ventilating Ceilings. Perforated ceilings…
    34. 606.2 Requirements. Ventilating ceilings shall comply
    35. 607.1 General.for Dwelling Units. An under-floor space shall b…
    36. 607.2 Dwelling Units. The use of under-floor space shall
    37. 607.3 Enclosed. Such spaces shall be cleaned of all loose
    38. 607.4 Flammable Materials. The enclosing material of the
    39. 607.5 Access. Access shall be through an opening in the
    40. 607.6 Automatic Control. A furnace supplying warm air
    41. 607.7 Temperature Limit. A furnace supplying warm air to
    42. 607.8 Noncombustible Receptacle. A noncombustible
    43. 607.9 Floor Registers. Floor registers shall be designed for
    44. 607.10 Exterior Wall and Interior Stud Partitions. Exterior wa…
    45. 607.11 Wall Register. Each wall register shall be connected
    46. 607.12 Distance from Combustible. A duct complying
    47. 607.13 Vapor Barrier. The entire ground surface of the
    48. 607.14 Prohibited. Fuel gas lines and plumbing waste
    49. 608.1 Air-Moving Systems and Smoke Detectors. 608.0 Automatic …
  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 — REFERENCED STANDARDS
  18. Appendix A — RESIDENTIAL PLAN EXAMINER REVIEW FORM FOR HVAC SY…
  19. Appendix B — PROCEDURES TO BE FOLLOWED TO PLACE GAS EQUIPMENT …
  20. Appendix C — INSTALLATION AND TESTING OF OIL (LIQUID) FUEL-FIR…
  21. Appendix D — FUEL SUPPLY: MANUFACTURED/MOBILE HOME PARKS AND R…
  22. Appendix E — SUSTAINABLE PRACTICES
  23. Appendix F — SIZING OF VENTING SYSTEMS AND OUTDOOR COMBUSTION …
  24. Appendix G — EXAMPLE CALCULATION OF OUTDOOR AIR RATE

GoCodebook provides public access, search, citation, multilingual explanation, and practical interpretation of legally adopted building regulations. It is not a substitute for the official ICC or California code publications.