Ch. 4 Ventilation Air — 2025 California Mechanical Code
California Mechanical Code (Title 24, Part 4) · 2025 edition · updated 2026-10-19 · California
CBSC: official editions, supplements and errata
Italicized text is a California amendment to the model code, as printed in the official publication.
Cite as: 2025 California Mechanical Code (Title 24, Part 4) Chapter 4 · Effective January 1, 2026 · Official source: Building Standards Commission
(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.)
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| Adopting Agency | BSC | BSC-CG | SFM | HCD 1 | HCD 2 | HCD 1-AC | DSA AC | DSA SS | DSA SS/CC | OSHPD 1 | OSHPD 1R | OSHPD 2 | OSHPD 3 | OSHPD 4 | OSHPD 5 | OSHPD 6 | BSCC | DPH | AGR | DWR | CEC | CA | SL | SLC |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Adopt Entire Chapter | X | |||||||||||||||||||||||
| Adopt Entire Chapter as amended (amended sections listed below) | X | X | X | X | X | X | X | |||||||||||||||||
| Adopt only those sections that are listed below | X | X | X | X | X | X | X | |||||||||||||||||
| Chapter/ |
||||||||||||||||||||||||
| 401.1 | X | X | X | X | X | X | X | |||||||||||||||||
| 401.3 | X | X | ||||||||||||||||||||||
| 401.3.1 | X | X | ||||||||||||||||||||||
| 402.1 | X | X | X | X | X | X | X | |||||||||||||||||
| 402.1.2 | X | X | X | X | X | X | ||||||||||||||||||
| 402.2 | † | † | † | † | † | |||||||||||||||||||
| 402.3 | X | X | † | † | † | † | † | |||||||||||||||||
| 403.0 | † | † | † | † | † | |||||||||||||||||||
| 403.7.2.1 – 403.7.2.4 | X | X | X | |||||||||||||||||||||
| 405.3 | X | X | ||||||||||||||||||||||
| 406.0 | X | X | X | X | X | |||||||||||||||||||
| 407.0 | X | X | X | X | X | X | ||||||||||||||||||
| 408.0 | X | X | X | X | X | X | ||||||||||||||||||
| 409.0 | X | X | X | X | X | X | ||||||||||||||||||
| 410.0 | X | X | X | X | X | X | ||||||||||||||||||
| 411.0 | X | X | X | X | X | |||||||||||||||||||
| 412.0 | X | X | X | X | X | |||||||||||||||||||
| 413.0 | X | X | X | X | X | |||||||||||||||||||
| 414.0 | X | X | X | X | X | |||||||||||||||||||
| 415.0 | X | X | X | X | X | |||||||||||||||||||
| 416.0 – 416.2 | X | X | X | X | X | |||||||||||||||||||
| 416.3 | X | |||||||||||||||||||||||
| 416.4 | X | X | X | X | X | |||||||||||||||||||
| 417.0 | X | X | X | X | X | |||||||||||||||||||
| 418.0 | X | X | X | X | X | X | ||||||||||||||||||
| 419.0 | X | |||||||||||||||||||||||
| Table 4-A | X | X | X | X | X | |||||||||||||||||||
| Table 4-B | X | X | X | |||||||||||||||||||||
| Table 4-C | X | X | ||||||||||||||||||||||
| Table 402.1 | X | X | ||||||||||||||||||||||
| Table 403.7 Notes 11 & 12 | X | X |
This state agency does not adopt sections identified with the following symbol: 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.
CHAPTER 4
VENTILATION AIR
401.0 General.¶
402.0 Ventilation Air.¶
403.0 Ventilation Rates.¶
[Not permitted for OSHPD 1, 2, 3, 4 & 5 spaces listed in Table 4-A]
404.0 Alternative Procedure for Multiple-Zone Systems Ventilation Efficiency.¶
404.0 Alternative Procedure for Multiple-Zone Sys- tems Ventilation Efficiency.
405.0 Ventilation for Residential Occupancies.¶
407.0 Ventilation System Details. [OSHPD 1, 1R, 2, 3, 4 & 5]¶
& 5]
408.0 Filters. [OSHPD 1, 1R, 2, 3, 4 & 5]¶
409.0 Ducts. [OSHPD 1, 1R, 2, 3, 4 & 5]¶
410.0 Laboratory Ventilating Systems and Hoods.¶
[OSHPD 1, 1R, 2, 3, 4 & 5]
411.0 Kitchen and Dining Areas. [OSHPD 1, 2, 3, 4 & 5]¶
412.0 Boiler, Mechanical, and Electrical Rooms.¶
[OSHPD 1, 2, 3, 4 & 5]
413.0 Odorous Rooms. [OSHPD 1, 2, 3, 4 & 5]¶
414.0 Airborne Infection Isolation Rooms. [OSHPD 1, 2, 3, 4 & 5]¶
1, 2, 3, 4 & 5]
415.0 Protective Environment Rooms. [OSHPD 1, 2, 3, 4 & 5]¶
4 & 5]
416.0 Alarms – Airborne Infection Isolation Rooms¶
and Protective Environment Rooms. [OSHPD 1, 2, 3, 4 & 5]
418.0 Design Requirements for Ethylene Oxide (ETO)¶
Sterilization Areas. [OSHPD 1, 1R, 2, 3, 4 & 5]
419.0 Neonatal Intensive Care Units. [OSHPD 1]¶
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