CMC · California Mechanical Code

Indoor pools (natatoriums) and special healthcare ventilation rules

Q: Can I size a natatorium ventilation system using CMC Table 402.1 rates?

No. The CMC § 401.2 requires natatorium ventilation to comply with the Uniform Swimming Pool, Spa and Hot Tub Code (USPSHTC); do not substitute generic CMC occupancy rates for pool spaces — follow the USPSHTC text and any California amendments referenced therein .

Q: Are direct evaporative coolers allowed in operating rooms or patient rooms?

No. § 406.0 restricts direct evaporative cooling (air contacting wetted pads/spray) to nonpatient areas such as laundries and boiler/machinery rooms; they are not permitted in patient‑care spaces without explicit approval by the enforcing agency .

Q: If I put an evaporative cooler in a hospital utility room, do I need filters?

Yes — the code requires filtration per Tables 4‑B and 4‑C for evaporative systems in health-care buildings, except where the tables specifically exempt utility rooms (e.g., laundries) — verify the exact table entries and show filters on the plans as required by § 406.0 .

Q: My indoor pool enclosure is 550 ft² — does the CMC require energy recovery on the dehumidifier?

Yes — Appendix E (E 503.5.10.4) of the CMC requires indoor pool dehumidifiers serving natatoriums with a heated pool over 500 ft² to include one of several specified energy‑recovery options; follow the Appendix E language when selecting the dehumidifier .

Q: Who decides if an evaporative cooler may serve a space that is “similar” to a boiler room?

The enforcing agency has authority to approve evaporative cooling in rooms that are “similar” to boiler/machinery rooms on a case‑by‑case basis; document the justification and obtain written approval per § 406.0 .

For homeowners: the California Mechanical Code does not give a pool ventilation recipe — it directs designers to the Uniform Swimming Pool, Spa & Hot Tub Code for indoor pools (see **§ 401.2**). In hospitals, the CMC limits direct evaporative coolers (those that wet the air) to nonpatient utility rooms like laundries or boiler rooms and requires synthetic pads and the filtration called out in the code (see **§ 406.0**). If your project involves a public or healthcare pool or any evaporative cooling in a medical facility, show the applicable standard on the plans and confirm allowances with the enforcing agency.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

The California Mechanical Code says the ventilation design for an indoor swimming pool (natatorium) must be done to the Uniform Swimming Pool, Spa and Hot Tub Code — i.e., the CMC defers natatorium ventilation design to the USPSHTC (§ 401.2) .
For health-care spaces the CMC limits certain equipment types: direct evaporative cooling (where air contacts wetted pads or sprays) is restricted to nonpatient areas (e.g., laundry, boiler or machinery rooms) and must use synthetic pads and required filtration per the code (§ 406.0) .
(Related health-care ventilation rules in Chapter 4 require design to ASHRAE/ASHE 170 and Table 4‑A for patient-care spaces — see Related provisions below) .

The single most important rule: natatorium ventilation must follow the Uniform Swimming Pool, Spa and Hot Tub Code; evaporative coolers that wet the air are generally not allowed in patient-care areas and are limited to utility/nonpatient spaces in hospitals per § 401.2 and § 406.0.

Requirements in detail

Natatoriums (indoor pools) — what to apply, and where to look

Primary requirement: design of ventilation systems serving a natatorium must comply with the Uniform Swimming Pool, Spa and Hot Tub Code — the CMC does not give specific natatorium ventilation rates itself; instead it delegates to the USPSHTC (§ 401.2) .
Practical effect: do not attempt to use other CMC tables (e.g., Table 402.1 for generic occupancies) to set pool deck or pool‑hall ventilation rates — follow USPSHTC wording, manufacturers’ dehumidifier/ventilation guidance, and any California amendments referenced by the USPSHTC.

Evaporative cooling and health-care spaces (what § 406.0 says)

Direct evaporative cooling systems (air contacts wetted pad/spray) are limited to nonpatient areas in health facilities — examples specifically allowed include laundry rooms, boiler rooms, and machinery rooms; other similar rooms may be allowed only with explicit approval by the enforcing agency (§ 406.0) .
Evaporative pads must be synthetic.
Filtration is required in accordance with Tables 4‑B and 4‑C, except for evaporative coolers serving utility/boiler/machinery rooms where the code specifically allows no filters for that application (§ 406.0) .

How these interact with general healthcare ventilation rules

The CMC requires mechanical ventilation for health-care facilities to be designed and installed in accordance with this code, ASHRAE/ASHE 170, and NFPA 99; where conflicts occur the most restrictive requirement prevails. The CMC also replaces certain ASHRAE 170 tables with Table 4‑A contained in the CMC (see Section 402.1.2) .
In short: for patient-care spaces follow ASHRAE 170 + Table 4‑A; for evaporative systems in health-care buildings, respect the limitations in § 406.0 and the filter/table requirements referenced there .

Quick decision table (what to check, values, and code reference)

Decision point	Typical value / rule	Applies to	Code reference
Who governs natatorium ventilation	Uniform Swimming Pool, Spa and Hot Tub Code (USPSHTC)	Indoor pools / natatoriums	§ 401.2
Allow direct evaporative coolers in patient-care areas?	No — limited to nonpatient utility rooms (laundry, boiler, machinery)	Health‑care facilities	§ 406.0
Evaporative pad material	Synthetic pads required	Evaporative coolers in health facilities	§ 406.0
Required filters for evaporative coolers	Filters per Tables 4‑B and 4‑C (except utility rooms)	Health‑care facilities	§ 406.0
Healthcare ventilation design standard	ASHRAE/ASHE 170 and NFPA 99; use Table 4‑A where adopted	Patient-care spaces	§ 402.1.2
Indoor pool dehumidifier energy recovery trigger (related)	Pools > 500 ft² — dehumidifier must include specified energy recovery options	Natatoriums (CMC Appendix E)	E 503.5.10.4

(If you need the USPSHTC text or ASHRAE 170 tables, consult those standards and the local enforcing agency; the CMC explicitly points you to them for natatoriums and for healthcare ventilation design)

Exceptions & special cases

§ 401.2 is not a “blanket” technical method — it delegates natatorium ventilation metrics to the USPSHTC. If your project is in California you must apply the USPSHTC requirements as adopted/modified locally (CMC § 401.2) .
§ 406.0 permits evaporative cooling in health-care buildings only in nonpatient rooms; the enforcing agency can approve other similar utility-type rooms case‑by‑case (§ 406.0) .
Filters required by Tables 4‑B/4‑C are waived for evaporative coolers serving laundries (utility rooms) — check the exact table entries before omitting filters in other areas (§ 406.0 and Table references) .
Where the CMC references ASHRAE 170 and NFPA 99 for healthcare ventilation, the CMC also specifies modifications (e.g., replacing some ASHRAE tables with Table 4‑A); follow the CMC’s listed modifications when designing for California (§ 402.1.2) .

Common mistakes

Assuming the CMC gives explicit pool ventilation rates. It does not — § 401.2 delegates natatorium ventilation to the USPSHTC. Using a generic office or gym rate instead of USPSHTC guidance is a frequent error .
Installing a direct evaporative cooler in a patient treatment or patient sleeping area. § 406.0 forbids direct evaporative systems in patient areas; they are limited to nonpatient utility rooms unless approved by the enforcing agency .
Forgetting the filtration and material requirements — evaporative pads must be synthetic and filtration requirements in Tables 4‑B and 4‑C still apply except where explicitly exempted in § 406.0 .
Overlooking the CMC modifications to ASHRAE 170: when designing health-care HVAC, read § 402.1.2 to apply the CMC’s specific changes and Table 4‑A where adopted .

Worked example — concrete scenarios applying the rules

Scenario A — Indoor pool (natatorium) in a small community center

Project: new indoor pool, pool water surface area 600 ft² (pool + deck spaces).
What the CMC requires: because this is an indoor pool, the ventilation design must be done to the Uniform Swimming Pool, Spa and Hot Tub Code — the CMC does not provide pool ventilation rates; you must follow USPSHTC requirements for airflow, dehumidification, make‑up air, corrosion control, exhaust, and associated equipment (§ 401.2) .
Related (energy) note: the CMC Appendix E requires indoor pool dehumidifiers serving natatoriums with heated pools over 500 ft² to include specified energy‑recovery measures (e.g., exhaust sensible energy recovery ≥50%, condenser heat-recovery capable of using 100% of dehumidification heat to heat pool water, or enthalpy recovery ≥50%) — since this pool is 600 ft² that Appendix E requirement applies, so coordinate dehumidifier selection accordingly (see E 503.5.10.4) .

Scenario B — Evaporative cooler in a hospital laundry room

Project: install a direct evaporative cooler (air contacts wetted pads) to serve a hospital laundry (nonpatient utility space).
What the CMC allows: § 406.0 permits direct evaporative cooling in nonpatient areas such as laundry rooms and boiler/machinery rooms; the evaporative pads must be synthetic, and filtration must be provided per Tables 4‑B/4‑C unless the area is specifically permitted by the code to be unfiltered (laundries may be exempt as shown in the tables) — document these decisions on the construction documents and confirm with the enforcing agency (§ 406.0) .
Practical checks: confirm pad material with manufacturer (synthetic), show filter selection/locations per Table 4‑B/4‑C on plans, and get enforcing agency approval if the evaporative system will serve any space adjacent to patient-care areas.

Related provisions (good to read next)

§ 401.2 — Indoor Swimming Pools (natatoriums) — delegates to USPSHTC.
§ 401.3 — Filters; MERV 13 requirement for mechanically ventilated buildings (California amendment).
§ 402.1.2 — Ventilation in Health Care Facilities: design per CMC, ASHRAE/ASHE 170, NFPA 99; CMC replaces certain ASHRAE 170 tables with Table 4‑A.
Table 4‑A (in Chapter 4) — Minimum ventilation rates for many health-care spaces (used in lieu of some ASHRAE 170 tables).
§ 406.0 — Evaporative Cooling System for Health Care Facilities (limits on direct evaporative systems; pad & filter requirements).
E 503.5.10.4 (Appendix E) — Indoor pool dehumidifier energy recovery requirements for pools > 500 ft².
§ 407.0 – § 408.0 series — Ventilation system details and filter requirements for hospitals and other medical occupancies (useful when designing HVAC systems serving health-care facilities).

Code references

Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:

CMC § 401.2 High relevance — show source text
401.2 Indoor Swimming Pools. The design of ventilation systems serving an indoor aquatic facility (natatorium) shall comply with the Uniform Swimming Pool, Spa and Hot Tub Code (USPSHTC).

401.3 Filters. [BSC-CG & DSA-SS] In mechanically ven- tilated buildings, provide regularly occupied areas of the building with air filtration media for outside and return air that provides at least a Minimum Efficiency Reporting Value (MERV) of 13. MERV 13 filters shall be installed prior to occupancy, and recommendations for maintenance with fil- ters of the same value shall be included in the operation and maintenance manual in compliance with Chapter 5, Division 5.5 of the California Green Building Standards Code (CAL- Green).

Exception: Existing mechanical equipment.

401.3.1 Labeling. Installed filters shall be clearly labeled by the manufacturer indicating the MERV rating.

402.0 Ventilation Air.

402.1 Occupiable Spaces. Occupiable spaces listed in Table 402.1 shall be designed to have ventilation (outdoor) air for occupants in accordance with this chapter. [DSA-SS] Ven- tilation air requirements for occupancies regulated by the California Energy Commission are found in the California Energy Code.

[CEC] Ventilation air requirements for occupancies regu- lated by the California Energy Commission and found in the California Energy Code supersede those of the California Mechanical Code.

[OSHPD 1, 2, 3, 4 & 5] Health care spaces shall meet the ventilation requirements found in Table 4-A. Ventilation rates for areas not specified in Table 4-A shall have minimum ven- tilation and air change rates per ANSI/ASHRAE Standard 62.1. Where areas with prescribed ventilation rates in both Standards 62.1 and Table 4-A exist, the higher of the two air change rates shall be used.

402.1.1 Construction Documents. The outdoor air ventilation rate and air distribution assumptions made in the design of the ventilation system shall be clearly identified on the construction documents.

402.1.2 Ventilation in Health Care Facilities.

Mechanical ventilation for health care facilities shall be designed and installed in accordance with this code, ASHRAE/ASHE 170, and NFPA 99. [OSHPD 1, 1R, 2, 3, 4 & 5] Ventilation for health care facilities shall be designed and installed in accordance with this code and Table 4-A. All supply-air, return air, and exhaust-air sys- tems shall comply with this code and ASHRAE 170. When the requirements of this code conflict with ASHRAE 170, the most restrictive requirements shall prevail. The text of ASHRAE 170 shall be modified as follows:

(1) ASHRAE 170. Section 6.1.2.1 -- Also see Section 319.0.

(2) ASHRAE 170. Section 6.3.1.3 – Modify as follows: Relief air other than class 1 shall discharge at least 10 feet (3048 mm) from any outside air intake.
CMC § 303.10.1 High relevance — show source text
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TABLE OF CONTENTS

323.0 Mechanical Equipment

Schedules . . . . . . . . . . . . . . . . . . . 62

324.0 Diesel-Powered Emergency

Generators . . . . . . . . . . . . . . . . . . . 62

325.0 Alternate Source of Power for

Safe Temperatures. . . . . . . . . . . . . 62

Table 303.10.1 Reduction of Clearances with

Specified Forms of Protection . . . . 63

Table 313.3 Hangers and Supports . . . . . . . . . . 65

CHAPTER 4 VENTILATION AIR . . . . . . . . . . . . 67

401.0 General. . . . . . . . . . . . . . . . . . . . . . 69

401.1 Applicability. . . . . . . . . . . . . . . . . . . 69

401.2 Indoor Swimming Pools . . . . . . . . . 69

401.3 Filters . . . . . . . . . . . . . . . . . . . . . . . 69

402.0 Ventilation Air . . . . . . . . . . . . . . . . . 69

402.1 Occupiable Spaces. . . . . . . . . . . . . 69

402.2 Natural Ventilation Procedure. . . . . 70

Table Minimum Openable Areas:

402.2.1.6(A)(1) Single Openings . . . . . . . . . . . . . . . 71

Table Minimum Openable Areas:

402.2.1.6(A)(2) Two Vertically

Spaced Openings . . . . . . . . . . . . . . 71

402.3 Mechanical Ventilation . . . . . . . . . . 71

402.4 Outdoor Air Intakes. . . . . . . . . . . . . 71

Table 402.4.1 Air Intake Minimum

Separation Distance . . . . . . . . . . . . 72

403.0 Ventilation Rates . . . . . . . . . . . . . . 72

403.1 General. . . . . . . . . . . . . . . . . . . . . . 72

403.2 Zone Calculations. . . . . . . . . . . . . . 73

403.3 Single-Zone Systems . . . . . . . . . . . 73

403.4 One Hundred Percent Outdoor

Air Systems . . . . . . . . . . . . . . . . . . 73

403.5 Multiple-Zone Recirculating Systems . . . . . . . . . . . . . . . . . . . . . 73

403.6 Design for Varying Operating Conditions. . . . . . . . . . . . . . . . . . . . 74

403.7 Exhaust Ventilation. . . . . . . . . . . . . 74

403.8 Dynamic Reset . . . . . . . . . . . . . . . . 75

403.9 Air Classification and
CMC § 403.7 Medium relevance — show source text
1
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.

2025 CALIFORNIA MECHANICAL CODE 67

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68 2025 CALIFORNIA MECHANICAL CODE

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CHAPTER 4

VENTILATION AIR

401.0 General.

401.1 Applicability. This chapter contains requirements for ventilation air supply, exhaust, and makeup air requirements for occupiable spaces within a building. [OSHPD 1, 1R, 2, 3, 4 & 5] See Sections 406.0 through 419.0. [SFM] Air filters shall comply with all requirements of Part 12, Title 24, Chap- ter 12-71, SFM Standard 12-71-1. Spaces within buildings, except those within a dwelling unit in residential occupancies where occupants are nontransient, shall comply with Section 402.0 through Section 404.0. Requirements for ventilation air rate for dwelling units in residential occupancies, where the occupants are nontransient, shall be in accordance with Section 405.0 or ASHRAE 62.2.

401.2 Indoor Swimming Pools. The design of ventilation systems serving an indoor aquatic facility (natatorium) shall comply with the Uniform Swimming Pool, Spa and Hot Tub Code (USPSHTC).

401.3 Filters. [BSC-CG & DSA-SS] In mechanically ven- tilated buildings, provide regularly occupied areas of the building with air filtration media for outside and return air that provides at least a Minimum Efficiency Reporting Value (MERV) of 13. MERV 13 filters shall be installed prior to occupancy, and recommendations for maintenance with fil- ters of the same value shall be included in the operation and maintenance manual in compliance with Chapter 5, Division 5.5 of the California Green Building Standards Code (CAL- Green).

Exception: Existing mechanical equipment.

401.3.1 Labeling. Installed filters shall be clearly labeled by the manufacturer indicating the MERV rating.

402.0 Ventilation Air.

402.1 Occupiable Spaces. Occupiable spaces listed in Table 402.1 shall be designed to have ventilation (outdoor) air for occupants in accordance with this chapter. [DSA-SS] Ven- tilation air requirements for occupancies regulated by the California Energy Commission are found in the California Energy Code.

[CEC] Ventilation air requirements for occupancies regu- lated by the California Energy Commission and found in the California Energy Code supersede those of the California Mechanical Code.
CMC § 4-1 Medium relevance — show source text
CHAPTER 4 SPECIAL DETAILED REQUIREMENTS

BASED ON OCCUPANCY AND USE . . . . . . . . . . . . . . . . . . . .4-1

401 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

402 Covered Mall and Open Mall Buildings . . . . . . . . . . . . 4-5

403 High-Rise Buildings and Group I-2 Occupancies Having Occupied Floors Located More Than 75 Feet above the Lowest Level of

Fire Department Vehicle Access . . . . . . . . . . . . . . . 4-9

404 Atriums. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

405 Underground Buildings . . . . . . . . . . . . . . . . . . . . . . . . 4-13

406 Motor-Vehicle-Related Occupancies. . . . . . . . . . . . . 4-15

407 Group I-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19

408 Group I-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-24

409 Motion Picture Projection Rooms . . . . . . . . . . . . . . . 4-30

410 Stages, Platforms and Technical Production Areas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-31

411 Special Amusement Areas . . . . . . . . . . . . . . . . . . . . . . 4-32

412 Aircraft-Related Occupancies . . . . . . . . . . . . . . . . . . . 4-33

413 Combustible Storage . . . . . . . . . . . . . . . . . . . . . . . . . . 4-37

414 Hazardous Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-37

415 Groups H-1, H-2, H-3, H-4 and H-5 . . . . . . . . . . . . . . . 4-42

416 Spray Application of Flammable Finishes . . . . . . . . 4-51

417 Drying Rooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-52

418 Organic Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-52

419 Artificial Decorative Vegetation . . . . . . . . . . . . . . . . . 4-52

CMC § 90.1 Medium relevance — show source text

[ASHRAE 90.1: TABLE 6.4.3.4.3]

Col1	OUTDOOR AIR INTAKE (CFM/ft2)	Col3	EXHAUST/RELIEF (CFM/ft2)	Col5
CLIMATE ZONE	NONMOTORIZED1	MOTORIZED	NONMOTORIZED3	MOTORIZED
0, 1, 2	0, 1, 2	0, 1, 2	0, 1, 2	0, 1, 2
Any height	20	4	20	4
3	3	3	3	3
Any height	20	10	20	10
4, 5B, 5C	4, 5B, 5C	4, 5B, 5C	4, 5B, 5C	4, 5B, 5C
Fewer than three stories	204	10	20	10
Three or more stories	204	10	204	10
5A, 6, 7, 8	5A, 6, 7, 8	5A, 6, 7, 8	5A, 6, 7, 8	5A, 6, 7, 8
Fewer than three stories	204	4	20	4
Three or more stories	204	4	204	4

For SI units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute = 0.00047 m [3] /s, 1 cubic foot per minute = 0.4719 L/s, 1 cubic foot per minute per square foot = 5.08 [(L/s)/m [2] ], 1 inch water gauge = 0.249 kPa

Notes:

1 When tested in accordance with AMCA 500D.

2 Dampers smaller than 12 inches (305 mm) in height, width, or diameter need not be tested but shall be of the same design and construction as the smallest tested damper meeting the listed leakage rate requirement.

3 Nonmotorized dampers smaller than 24 inches (610 mm) in height, width, or diameter shall be permitted to have a leakage rate of 40 CFM/ft 2 [0.203 (m 3 /s)/m 2 ].

4 Where permitted by Section E 503.4.6.4.1, exception 2.

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APPENDIX E

(2) Systems serving zones where humidity levels are required to be maintained with precision of not more than ±5 percent relative humidity to comply with applicable codes or accreditation standards or as approved by the Authority Having Jurisdiction.

[ASHRAE 90.1:6.4.3.6.2]

CMC § 503.7.1 Medium relevance — show source text
** Heat pumps equipped with internal electric resistance heaters shall have controls that prevent supplemental heater operation where the heating load is capable of being met by the heat pump alone during both steady-state operation and setback recovery. Supplemental heater operation shall be permitted during outdoor coil defrost cycles. Exception: Heat pumps whose minimum efficiency is regulated by U.S. National Appliance Energy Conservation Act (NAECA) and whose ratings are in accordance with the requirements shown in Table E 503.7.1(2) and includes the use of an internal electric resistance heating. [ASHRAE 90.1:6.4.3.5] E 503.4.6.7 Humidification and Dehumidifica- tion Control. Humidification and dehumidification

control shall be in accordance with Section E 503.4.6.7.1 through Section E 503.4.6.7.3. E 503.4.6.7.1 Dehumidification. Humidistatic controls shall not use mechanical cooling to reduce the humidity below the lower of a dew point of 55°F (12.8°C) or relative humidity of 60 percent in the coldest zone served by the system. Exceptions: (1) Lower humidity shall be permitted when operating mechanical cooling for temperature control.

(2) Systems serving zones where specific humidity levels are required, such as museums and hospitals, and approved by the Authority Having Jurisdiction or required by accreditation standards, and where humidistatic controls are capable of and configured to maintain a dead band of at least 10 percent relative humidity where no active humidification or dehumidification takes place.

(3) Systems serving zones where humidity levels are required to be maintained with precision of not more than ±5 percent relative humidity to comply with applicable codes or accreditation standards or as approved by the Authority Having Jurisdiction.

[ASHRAE 90.1:6.4.3.6.1]

E 503.4.6.7.2 Humidification. Humidistatic controls shall not use fossil fuel or electricity to produce relative humidity above 30 percent in the warmest zone served by the system.

Exceptions:

(1) Systems serving zones where specific humidity levels are required, such as museums and hospitals, and approved by the Authority Having Jurisdiction or required by accreditation standards, and where humidistatic controls are capable of and configured to maintain a dead band of at least 10 percent relative humidity where no active humidification or dehumidification takes place.

TABLE E 503.4.6.4.2 MAXIMUM DAMPER LEAKAGE [1, 2]

(cubic foot per minute per square foot) at 1.0 inch water gauge

[ASHRAE 90.1: TABLE 6.4.3.4.3]
CMC § 1220.4.2 Medium relevance — show source text
8|1220.4.2 – 1220.4.6| |1221.7|1221.6| |1308.2 – 1308.4.1|1308.3 – 1308.5.1| |Table 1308.3.1|Table 1308.4.1| |1308.4.2|1308.5.2| |1308.4.2.2 – 1308.6.4|1308.5.2.1 – 1308.7.3| |Table 1308.4.6.2|Table 1308.5.6.2| |1308.6.5 – 1308.13.1|1308.7.7 – 1308.14.1| |1312.1.2 – 1312.1.3|1312.1.1 – 1312.1.2| |Chapter 17|Appendix F| |Chapter 18|Chapter 17| |D 103.2|D 103.1| |E 503.5.6.7|E 503.5.6.6| |E 503.5.7.2 – E 503.5.7.6|E 503.5.7.1 – E 503.5.7.5| |Table E 503.5.7.2|Table E 503.5.7.1| |Table E 503.5.7.6|Table E 503.5.7.5| |Table E 503.5.10.1.2(1)|Table E 503.5.10(1)| |Table E 503.5.10.1.2(2)|Table E 503.5.10(2)| |E 503.5.10.1.2|E 503.5.10| |E 503.5.10.2 – E 503.5.10.2.2|E 503.5.10.1 – E 503.5.10.1.2| |E 503.5.12.1|E 503.5.12| |E 503.5.12.2|E 503.5.12.1| |E 503.6.5.4|E 503.6.5.4.1|

xxii 2025 CALIFORNIA MECHANICAL CODE

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CMC § 1.8.4.1 Medium relevance — show source text
**_ 1.8.4.1 Permits. A written construction permit shall be obtained from the enforcing agency prior to the erection, construction, reconstruction, installation, relocation, or alteration of any mechanical system. Exceptions: (1) Work exempt from permits as specified in Chapter 1, Scope and Administration, Division II, Section 104.2 Items (1) through (5) of this code. (2) Changes, alterations, or repairs of a minor nature not affecting structural features, egress, sanitation, safety, or accessibility as determined by the enforcing agency.

(3) Retroactive permits issued in accordance with Health and Safety Code Section 17958.12.

Exemptions from permit requirements shall not be deemed to grant authorization for any work to be done in any manner in violation of other provisions of law or this code. 1.8.4.2 Fees. Subject to other provisions of law, the governing body of any city, county, or city and county may prescribe fees to defray the cost of enforcement of rules and regulations promulgated by the Department of Housing and Community Development. The amount of the fees shall not exceed the amount reasonably neces- sary to administer or process permits, certificates, forms, or other documents, or to defray the costs of enforcement. For additional information, see State Housing Law, Health and Safety Code, Division 13, Part 1.5, Section 17951 and California Code of Regulations, Title 25, Divi- sion 1, Chapter 1, Subchapter 1, Article 3, commencing with Section 6.

1.8.4.3 Plan Review and Time Limitations. Subject to other provisions of law, provisions related to plan checking, prohibition of excessive delays, and contracting with or employment of private parties to perform plan checking are set forth in the State Housing Law, Health and Safety Code Section 17960.1, and for employee housing, in Health and Safety Code Section 17021. 1.8.4.3.1 Retention of Plans. The building depart- ment of every city, county, or city and county shall maintain an official copy, microfilm, or electronic or other type of photographic copy of the plans of every building, during the life of the building, for which the department issued a building permit. Exceptions: (1) Single or multiple dwellings not more than two stories and basement in height. (2) Garages and other structures appurtenant to buildings listed in Exception 1. (3) Farm or ranch buildings appurtenant to build- ings listed in Exception 1. (4) Any one-story building where the span between bearing walls does not exceed 25 feet (7620 mm), except a steel frame or concrete building. All plans for common interest developments as defined in Section 4100 of the California Civil Code shall be retained. For additional information regarding plan retention and reproduction of plans by an enforcing agency, see Health and Safety Code Sections 19850 through 19852. 1.8.4.4 Inspections. Construction or work for which a permit is required shall be subject to inspection by the building official and such construction or work shall remain accessible and exposed for inspection purposes _until approved.

CMC § 422.1 Medium relevance — show source text

places of wor-
ship, museums, libraries,
lecture halls, gymnasiums
(without spectator seat-
ing), indoor pools (with-
out spectator seating)|Over 400, add 1 fixture for
each additional 500 males
and 1 fixture for each
additional 125 females.|Over 400, add 1 fixture for
each additional 500 males
and 1 fixture for each
additional 125 females.|Over 600,
add 1 fixture
for each
additional
300 males.|Over 750, add 1 fixture for
each additional 250 males
and 1 fixture for each
additional 200 females.|Over 750, add 1 fixture for
each additional 250 males
and 1 fixture for each
additional 200 females.|Over 750, add 1 fixture for
each additional 250 males
and 1 fixture for each
additional 200 females.|Over 750,
add 1 fixture
for each
additional
500 persons.|Over 750,
add 1 fixture
for each
additional
500 persons.|

70 2025 CALIFORNIA PLUMBING CODE

PLUMBING FIXTURES AND FIXTURE FITTINGS

TABLE 422.1 MINIMUM PLUMBING FACILITIES [1] (continued)

TYPE OF OCCUPANCY2	WATER CLOSETS (FIXTURES PER PERSON)3	Col3	URINALS (FIXTURES PER PERSON)4	LAVATORIES (FIXTURES PER PERSON)5	Col6	BATHTUBS OR SHOWERS (FIXTURES PER PERSON)	DRINKING FOUNTAINS/ FACILITIES (FIXTURES PER PERSON)	OTHER6, 7
A-4 Assembly occupancy (indoor activities or sport- ing events with spectator seating)- swimming pools, skating rinks, are- nas, and gymnasiums	Male 1: 1-100 2: 101-200 3: 201-400	Female 1: 1-25 2: 26-50 3: 51-100 4: 101-200 6: 201-300 8: 301-400	Male 1: 1-100 2: 101-200 3: 201-400 4: 401-600	Male 1: 1-200 2: 201-400 3: 401-750	Female 1: 1-100 2: 101-200 4: 201-300 5: 301-500 6: 501-750	––	1: 1-250 2: 251-500 3: 501-750	1 service sink or laundry sink
A-4 Assembly occupancy (indoor activities or sport- ing events with spectator seating)- swimming pools, skating rinks,

CMC § 0.0929 Medium relevance — show source text
(1) 60 CFM/person for cultivation, production, and processing facilities or factories.

(2) 15 CFM/person for centers and dispensaries.

Ra = outdoor airflow rate required per unit area, 1 CFM/ft [2]

For SI Units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute =

0.0283 m [3] /min, 1 cubic foot per minute = 0.4719 L/s, 1 cubic foot per

minute per square foot = 5.08 [(L/s)/m [2] ]

Sample Calculation: Determine the outdoor airflow required in the breathing zone ( Vbz ) of an indoor space used for horticultural cultivation with an occupiable floor area of 800 square feet and a maximum of 5 people expected to occupy the zone.

Sample Solution: Vbz = Rp - Pz + Ra - Az Vbz = (60 CFM/person • 5 people) + (1 CFM • 800 SF) Vbz = 1100 CFM. The ventilation system shall be capable of providing not less than 1100 CFM of outdoor air.

I 801.1.2 Ventilation System Requirements. When activated by the gas detection system required by Section I 601.1, the mechanical purge ventilation system shall remain on until manually reset. The purge ventilation system ducting shall terminate outdoors in an approved location. The ventilation system shall be designed to operate at a negative pressure of 0.01 inches water column (0.002 kPa) in relation to the exhausted indoor space.

I 801.1.3 Ventilation for Indoor Cultivation and Storage Spaces. Indoor spaces used for horticultural cultivation and processing and storage shall be provided with ventilation in accordance with Section 402.2. Where

mechanical ventilation is provided, the systems shall be operational when the indoor space(s) are occupied. Air in indoor cultivation and storage spaces shall be classified as Class 2 Air in accordance with Section 403.9.2.

I 801.1.4 Exhaust Ventilation Rate. The exhaust and ventilation system required in this section shall not create a lesser standard of installation than prescribed by the

minimum safety standards adopted by the Authority Having Jurisdiction. Exhaust airflow shall be provided at not less than 0.2 CFM/ft [2] [1.02 (L/s)/m [2] ] of floor area. Exhaust air shall not be used as makeup air, recirculated air, or transfer air. Makeup air shall be provided for more than 150 CFM (70.8 L/s) exhaust. I 801.1.5 Exhaust System Requirements. An exhaust system shall be installed in accordance with Section 505.0 and the following requirements:

(1) Exhaust outlet location(s) in accordance with Section 502.2.3 for product conveying ducts as classified in Section 505.8.

(2) Exhaust air shall terminate directly to the outdoors and shall not be directed onto a public way.

(3) The exhaust inlet shall be not less than 12 inches (305 mm) above the finished floor.

(4) Chemical fume hoods shall be required for flammable solvent processing, shall be listed, and shall be installed in accordance with the manufacturer’s

installation instructions.

(5) Exhaust ducts shall be independent of all other exhaust systems.

(6) The exhaust rate shall be in accordance with the appliable occupancy category as shown in Table 403.7.
CMC § 517.34. Medium relevance — show source text
12. Transformers.

13. Electrical substations.

14. UPS and batteries.

15. Panelboards as defined in the California Electrical Code (CEC) Article 100. 16. Industrial control panels as defined in the California Electrical Code (CEC) Article 100. 17. Power isolation and correction systems. 18. Motorized surgical lighting systems. 19. Motorized operating table systems. 20. Internal communication servers, routers and switches failure of which could impair the continued operation of the facility. 21. Medical gas and vacuum systems. 22. Electrical busways as defined in UL 857. 23. Electrical control panels powered by the life safety branch in accordance with the California Electrical Code (CEC) Article 517.33 or the critical branch in accordance with the California Electrical Code (CEC) Article 517.34.

Exceptions: 1. Equipment and components weighing not more than 75 lbs. rigidly attached to structures or surface mounted on equipment or components that are not required to have special seismic certification by this section. 2. Mobile equipment/components. 3. Pipes, ducts, conduits and cable trays, excluding in-line equipment and components. 4. Underground tanks. 5. Electric motors, base-mounted horizontal pumps and compressors. 6. Based-mounted vertical pumps up to 20 hp. 7. Substitution of certified active subcomponents up to operating weight of 10 lbs. 8. Components where importance factor, I p , is permitted to be 1.0 by this code. 9. Emergency generators up to 25 kilowatts. 10. Equipment and components used for clinical trials only. 11. Elevator machines and governors. 12. Temporary and Interim equipment.

For Exceptions 5, 6 and 7:

Exempt subcomponents, which are an integral part of equipment that require special seismic certification, shall be tested attached to the equipment. Exempt subcomponents shall be permitted to be substituted without testing, provided that the substituted subcomponent relative to the certified subcomponent has: 1. Similar configuration with equivalent function. 2. Supports and attachments of similar configuration with equivalent strength and stiffness.

3. Same attachment location.

2025 CALIFORNIA BUILDING CODE 17A-19

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

�

�

SPECIAL INSPECTIONS AND TESTS

4. Changes in dimensions, center of gravity and mass, of not more than 10 percent of the certified subcomponent and still meets Exception 5, 6 or 7. 5. Manufacturing process with ISO 9001 certification.

1705 A .14.4 Seismic isolation and damping systems. Seismic isolation and damping systems in structures assigned to Seismic Design Category D, E or F shall be tested in accordance with Section 17.8 and 18.6 of ASCE 7.

Prototype and production testing and associated acceptance criteria for isolator units and damping devices shall be subject to preapproval by the building official. Testing exemption for similar units shall require approval by the building official.
CMC § 6-2021 Medium relevance — show source text
ANSI/NEMA WD 6-2021 Wiring Devices—Dimensional Specifications

ANSI Z21.40.4a-1998 (R2022)/CGA 2.94a-M98 (R2022) Performance Testing and Rating of Gas-Fired, Air-Conditioning and Heat Pump Appliances

ANSI Z21.47-2021/CSA 2.3:21 Gas-Fired Central Furnaces

288 2025 CALIFORNIA ENERGY CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

STANDARDS AND DOCUMENTS REFERENCED IN THE ENERGY CODE

ANSI Z83.8-2016/CSA 2.6-2016 (R2021)

Gas Unit Heaters, Gas Packaged Heaters, Gas Utility Heaters and Gas-Fired Duct Furnaces (2016)

Available from:

American National Standards Institute 25 West 43rd Street, 4th floor New York, NY 10036 (212) 642-4900

ANSI/APSP/ICC-5-2011 American National Standard For Residential Inground Swimming Pools (2011 w/Addendum A)

Available from: Association of Pool & Spa Professionals 2111 Eisenhower Ave. Alexandria, VA 22314 (703) 838-0083

AMERICAN SOCIETY OF HEATING, REFRIGERATING AND AIR-CONDITIONING ENGINEERS (NATIONAL PUBLICATIONS)

ASHRAE GUIDELINE 36-2021 High-Performance Sequences of Operation for HVAC Systems

ANSI/ASHRAE Standard 52.2-2017

Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size

ANSI/ASHRAE Standard 55-2023

Thermal Environment Conditions for Human Occupancy

ANSI/ASHRAE Standard 62.1-2022 Ventilation and Acceptable Indoor Air Quality

ANSI/ASHRAE Standard 62.2-2022

Ventilation and Acceptable Indoor Air Quality in Residential Buildings

ANSI/ASHRAE Standard 84-2020 Method of Testing Air-to-Air Heat/Energy Exchangers

ANSI/ASHRAE/IES Standards 90.1-2022 Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings

ANSI/ASHRAE Standard 154-2022 Ventilation for Commercial Cooking Operations

ANSI/ASHRAE Standard 193-2010 (RA2014) Method of Test for Determining the Airtightness of HVAC Equipment

ASHRAE Handbooks

2023 ASHRAE Handbook - HVAC Applications Inch-Pound Edition

2020 ASHRAE Handbook - HVAC Systems and Equipment I-P Edition

2021 ASHRAE Handbook - Fundamentals I-P Edition

Available from: American Society of Heating,
```
                         Refrigerating and Air Conditioning Engineers
```
(ASHRAE) 1791 Tullie Circle N.E. Atlanta, GA 30329 www.ashrae.org

AMERICAN SOCIETY OF HEATING, REFRIGERATING AND AIR-CONDITIONING ENGINEERS (REGIONAL PUBLICATION)

ASHRAE Climatic Data for Region X Arizona, California, Hawaii, Nevada, Publication SPCDX, 1982, ISBN #20002196 and Supplement, 1994, ISBN #20002596

Available from: Order Desk Building News 10801 National Boulevard Los Angeles, CA 90064 (800) 873-6397 or (310) 474-7771 www.bnibooks.com/
CMC § 402.1.1 Medium relevance — show source text
402.1.1 Construction Documents. The outdoor air ventilation rate and air distribution assumptions made in the design of the ventilation system shall be clearly identified on the construction documents.

402.1.2 Ventilation in Health Care Facilities.

Mechanical ventilation for health care facilities shall be designed and installed in accordance with this code, ASHRAE/ASHE 170, and NFPA 99. [OSHPD 1, 1R, 2, 3, 4 & 5] Ventilation for health care facilities shall be designed and installed in accordance with this code and Table 4-A. All supply-air, return air, and exhaust-air sys- tems shall comply with this code and ASHRAE 170. When the requirements of this code conflict with ASHRAE 170, the most restrictive requirements shall prevail. The text of ASHRAE 170 shall be modified as follows:

(1) ASHRAE 170. Section 6.1.2.1 -- Also see Section 319.0.

(2) ASHRAE 170. Section 6.3.1.3 – Modify as follows: Relief air other than class 1 shall discharge at least 10 feet (3048 mm) from any outside air intake.

(3) ASHRAE 170. Section 6.3.2 -- Also see Section 407.1.2 and 407.2.2.

(4) ASHRAE 170. Section 6.4 -- Modify as follows:

c.: Replace Table 7-1, 8-1, 8-2, or 9-1 with Table 4-A.

d.: Replace Table 7-1, 8-1, 8-2, or 9-1 with Table 4-A.

(5) ASHRAE 170. Section 6.9 -- See also Section 605.2 and 605.3.

(6) ASHRAE 170. Section 7.1a -- Modify as follows:

Replace reference to Table 7-1 with reference to Table 4-A.

(7) ASHRAE 170. Section 7.2.1 c -- Not adopted.

(8) ASHRAE 170. Section 7.2.2 Also see Section 415.0.

(9) ASHRAE 170. Section 7.2.3 -- Not adopted.

(10)ASHRAE 170. Section 7.3.1 -- Modify as follows:

Replace reference to Table 7-1 with reference to Table 4-A.

(11) ASHRAE 170. Section 7.4.1 -- Modify as follows:

Delete the Exception that allows for high return grilles.

(12)ASHRAE 170. Section 8.1a -- Modify as follows: Replace reference to Table 8-1 with reference to Table 4-A.

(13)ASHRAE 170. Section 8.2 -- Modify as follows: Replace reference to Table 8-2 with reference to Table 4-A.

(14)ASHRAE 170. Section 9.1a -- Modify as follows: Replace reference to Table 9-1 with reference to Table 4-A.

2025 CALIFORNIA MECHANICAL CODE 69
CMC § 402.2.1.6 Medium relevance — show source text
402.2.1.6(A)(1) Single Openings . . . . . . . . . . . . . . . 71

Table Minimum Openable Areas:

402.2.1.6(A)(2) Two Vertically

Spaced Openings . . . . . . . . . . . . . . 71

402.3 Mechanical Ventilation . . . . . . . . . . 71

402.4 Outdoor Air Intakes. . . . . . . . . . . . . 71

Table 402.4.1 Air Intake Minimum

Separation Distance . . . . . . . . . . . . 72

403.0 Ventilation Rates . . . . . . . . . . . . . . 72

403.1 General. . . . . . . . . . . . . . . . . . . . . . 72

403.2 Zone Calculations. . . . . . . . . . . . . . 73

403.3 Single-Zone Systems . . . . . . . . . . . 73

403.4 One Hundred Percent Outdoor

Air Systems . . . . . . . . . . . . . . . . . . 73

403.5 Multiple-Zone Recirculating Systems . . . . . . . . . . . . . . . . . . . . . 73

403.6 Design for Varying Operating Conditions. . . . . . . . . . . . . . . . . . . . 74

403.7 Exhaust Ventilation. . . . . . . . . . . . . 74

403.8 Dynamic Reset . . . . . . . . . . . . . . . . 75

403.9 Air Classification and

Recirculation. . . . . . . . . . . . . . . . . . 75

Table 403.9 Airstreams or Sources

Description Air Class . . . . . . . . . . . 75

403.10 Air Balance . . . . . . . . . . . . . . . . . . . 75

404.0 Alternative Procedure for

Multiple-Zone Systems Ventilation Efficiency . . . . . . . . . . . 76

xxx

404.1 System Ventilation Efficiency . . . . . 76

404.2 Average Outdoor Air Fraction. . . . . 76

404.3 Zone Ventilation Efficiency . . . . . . . 76

405.0 Ventilation for Residential

Occupancies. . . . . . . . . . . . . . . . . . 77

405.1 General. . . . . . . . . . . . . . . . . . . . . . 77

405.2 Ventilation Air Rate. . . . . . . . . . . . . 77

405.3 Bathroom Exhaust . . . . . . . . . . . . . 77

405.4 Kitchen Exhaust . . . . . . . . . . . . . . . 77

405.5 Ventilation Openings . . . . . . . . . . . 77

406.0 Evaporative Cooling System for Health Care Facilities . . . . . . . . 78

407.0 Ventilation System Details . . . . . . . 78

407.1 General. . . . . . . . . . . . . . . . . . . . . . 78

407.2 Outdoor Air Intakes and
CMC § 403.9 Medium relevance — show source text
Table 403.9 Airstreams or Sources

Description Air Class . . . . . . . . . . . 75

403.10 Air Balance . . . . . . . . . . . . . . . . . . . 75

404.0 Alternative Procedure for

Multiple-Zone Systems Ventilation Efficiency . . . . . . . . . . . 76

xxx

404.1 System Ventilation Efficiency . . . . . 76

404.2 Average Outdoor Air Fraction. . . . . 76

404.3 Zone Ventilation Efficiency . . . . . . . 76

405.0 Ventilation for Residential

Occupancies. . . . . . . . . . . . . . . . . . 77

405.1 General. . . . . . . . . . . . . . . . . . . . . . 77

405.2 Ventilation Air Rate. . . . . . . . . . . . . 77

405.3 Bathroom Exhaust . . . . . . . . . . . . . 77

405.4 Kitchen Exhaust . . . . . . . . . . . . . . . 77

405.5 Ventilation Openings . . . . . . . . . . . 77

406.0 Evaporative Cooling System for Health Care Facilities . . . . . . . . 78

407.0 Ventilation System Details . . . . . . . 78

407.1 General. . . . . . . . . . . . . . . . . . . . . . 78

407.2 Outdoor Air Intakes and

Exhaust Outlets . . . . . . . . . . . . . . . 78

407.3 Air Balance. . . . . . . . . . . . . . . . . . . 78

407.4 Air Circulation . . . . . . . . . . . . . . . . . 78

407.5 Variable Air Volume . . . . . . . . . . . . 79

407.6 Economizers. . . . . . . . . . . . . . . . . . 79

407.7 Unoccupied Turndown. . . . . . . . . . 79

407.8 Building Pressurization . . . . . . . . . 80

408.0 Filters . . . . . . . . . . . . . . . . . . . . . . . 80

408.1 General. . . . . . . . . . . . . . . . . . . . . . 80

408.2 Filters for Hospitals. . . . . . . . . . . . . 80

408.3 Filters for Skilled Nursing Facilities, Intermediate Care Facilities, and Correctional

Treatment Centers . . . . . . . . . . . . . 80

408.4 Filters for Outpatient Facilities . . . . 80

408.5 Filters for Recirculating

Room Units. . . . . . . . . . . . . . . . . . . 80
CMC § 7-1 Medium relevance — show source text
d.: Replace Table 7-1, 8-1, 8-2, or 9-1 with Table 4-A.

(5) ASHRAE 170. Section 6.9 -- See also Section 605.2 and 605.3.

(6) ASHRAE 170. Section 7.1a -- Modify as follows:

Replace reference to Table 7-1 with reference to Table 4-A.

(7) ASHRAE 170. Section 7.2.1 c -- Not adopted.

(8) ASHRAE 170. Section 7.2.2 Also see Section 415.0.

(9) ASHRAE 170. Section 7.2.3 -- Not adopted.

(10)ASHRAE 170. Section 7.3.1 -- Modify as follows:

Replace reference to Table 7-1 with reference to Table 4-A.

(11) ASHRAE 170. Section 7.4.1 -- Modify as follows:

Delete the Exception that allows for high return grilles.

(12)ASHRAE 170. Section 8.1a -- Modify as follows: Replace reference to Table 8-1 with reference to Table 4-A.

(13)ASHRAE 170. Section 8.2 -- Modify as follows: Replace reference to Table 8-2 with reference to Table 4-A.

(14)ASHRAE 170. Section 9.1a -- Modify as follows: Replace reference to Table 9-1 with reference to Table 4-A.

2025 CALIFORNIA MECHANICAL CODE 69

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

VENTILATION AIR

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«

402.2.1.5 Corner Openings. For zones with operable openings on two adjacent sides of a zone, the distance from the operable openings shall be not more than 5 H along a line drawn between the two openings that are farthest apart. Floor area outside that line shall comply with Section 402.2.1.1 as a zone having openings on only one side of the zone.

[ASHRAE 62.1:6.4.1.5]

402.2.1.6 Location and Size of Openings. Zones or portions of zones to be naturally ventilated shall have a permanently open airflow path to openings directly connected to the outdoors. The minimum flow rate to the zone shall be determined in accordance with

Section 403.2.1. This flow rate shall be used to deter mine the required openable area of openings, accounting only for buoyancy-driven flow. Wind-driven flow shall be used only where it can be demonstrated that the minimum flow rate is provided during all occupied hours. Openings shall be sized in accordance with Section 402.2.1.6(A). Permanently open airflow path shall include, but not be limited to, pathways that would allow airflow unimpeded by partitions, walls, and furnishings. {ASHRAE 62.1:6.4.1.6}
CMC § 62.1. Medium relevance — show source text
(a) used for another energy recovery system,

(b) not allowed by ASHRAE/ASHE 170 for use in energy recovery systems with leakage potential, or

(c) of Class 4 as defined in Chapter 2 or ASHRAE 62.1.

(7) Heating energy recovery for systems in Climate Zones 0 through 4 requiring dehumidification during heating mode that employ energy recovery and have a minimum SERR of 0.40.

(8) Systems expected to operate less than 20 hours per week at the outdoor air percentage in accordance with Table E 503.5.10.1.2(1).

(9) Indoor pool dehumidifiers meeting Section E 503.5.10.4. [ASHRAE 90.1:6.5.6.1.2]

E 503.5.10.1.2(A) Minimum Enthalpy Recovery Ratio. Energy recovery systems required by this section shall result in an enthalpy recovery ratio of at least 50 percent. A 50 percent enthalpy recovery ratio shall mean a change in the enthalpy of the outdoor air supply equal to

»

(2) Nontransient dwelling units with no more than 500 ft [2] (46.45 m [2] ) of conditioned floor area in Climate Zone 0, 1, 2, 3,4C, and 5C. (3) Enthalpy recovery ratio requirements at heating design condition in Climate Zones 0, 1, and 2. (4) Enthalpy recovery ratio requirements at cooling design condition in Climate Zones 4, 5, 6, 7, 8. [ASHRAE 90.1:6.5.6.1.1] E 503.5.10.1.2 Exhaust Air Energy Recov- ery for Spaces Other than Nontransient Dwelling Units. Each fan system serving spaces other than nontransient dwelling units shall have an energy recovery system where the design supply fan airflow rate exceeds the value listed in Table E 503.5.10.1.2(1) and Table E 503.5.10.1.2(2), based on the climate zone and percentage of outdoor air at design airflow conditions. Table E 503.5.10.1.2(1) shall be used for all ventilation systems that operate less than 8000 hours per year and Table E 503.5.10.1.2(2) shall be used for all ventilation systems that operate 8000 or more hours per year.

For spaces other than nontransient dwelling units, energy recovery systems required by this section shall result in an enthalpy recovery ratio of not less than 50 percent. The energy recovery system shall provide the required enthalpy recovery ratio both heating and cooling design conditions, unless one mode is not required for the climate zone by the exceptions below. Provision shall be provided to bypass or control the energy recovery system to permit air economizer operation in accordance with Section E 503.5.1.

Exceptions:

(1) Laboratory systems that are in accordance with Section E 503.5.11.3.

(2) Systems serving spaces that are not cooled and that are heated to less than 60°F (16°C).

2025 CALIFORNIA MECHANICAL CODE 443

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

CMC § 62.1 Medium relevance — show source text

MINIMUM VENTILATION RATES IN BREATHING ZONE

[ASHRAE 62.1: TABLE 6-1]

OCCUPANCY CATEGORY	PEOPLE OUTDOOR Air Rate Rp (CFM/person)	AREA OUTDOOR Air Rate Ra (CFM/ft2)	DEFAULT OCCUPANT DENSITY (people/1000 ft2)	AIR CLASS
MISCELLANEOUS SPACES	MISCELLANEOUS SPACES	MISCELLANEOUS SPACES	MISCELLANEOUS SPACES	MISCELLANEOUS SPACES
Banks or bank lobbies	7.5	0.06	15	1
Bank vaults/safe deposit	5	0.06	5	2
Computer (not printing)	5	0.06	4	1
Freezer and refrigerated spaces (<50°F)	10	0	0	2
Manufacturing where hazardous materials are not used	10	0.18	7	2
Manufacturing where hazardous materials are used (excludes heavy industrial and chemical processes)	10	0.18	7	3
Pharmacy (prep. area)	5	0.18	10	2
Photo studios	5	0.12	10	1
Shipping/receiving	10	0.12	2	2
Sorting, packing, light assembly	7.5	0.12	7	2
Telephone closets	–	0.00	–	1
Transportation waiting	7.5	0.06	100	1
Warehouses	10	0.06	–	2
OFFICE BUILDINGS	OFFICE BUILDINGS	OFFICE BUILDINGS	OFFICE BUILDINGS	OFFICE BUILDINGS
Break Rooms	5	0.12	50	1
Main entry lobbies	5	0.06	10	1
Occupiable storage rooms for dry materials	5	0.06	2	1
Office space	5	0.06	5	1
Reception areas	5	0.06	30	1
Telephone/data entry	5	0.06	60	1
OUTPATIENT HEALTH CARE FACILITIES1,2,3	OUTPATIENT HEALTH CARE FACILITIES1,2,3	OUTPATIENT HEALTH CARE FACILITIES1,2,3	OUTPATIENT HEALTH CARE FACILITIES1,2,3	OUTPATIENT HEALTH CARE FACILITIES1,2,3
Birthing room	10	0.18	15	2
Class 1 imaging rooms	5	0.12	5	1
Dental operatory	10	0.18	20	1
General examination room	7.5	0.12	20	1
Other dental treatment areas	5	0.06	5	1
Physical therapy exercise area	20	0.18	7	2
Physical therapy individual room	10	0.06	20	1
Physical therapeutic pool area	–	0.48	–	2
Prosthetics and orthotics room	10	0.18	20	1
Psychiatric consultation room	5	0.06	20	1
Psychiatric examination room	5	0.06	20	1
Psychiatric group room	5	0.

CMC § 3.9.2 Medium relevance — show source text
3.9.2, 1810.3.9.4, 1810.3.9.4.1, 1810.3.9.4.2, 1810.3.11.2, 1810.3.12, 1811A.4, 1902.1, 1902.1.1, 2202.2.1, 2202.2.1.1, 2202.2.1.2, 2202.2.2, 2204.2.1, 2204.2.2, 2206.1.1.1, 2209.2, 2210A.2, 2211.1, 2212.1, 2212A.1.1, 2212A.2.4, Table 2304.6.1, Table 2306.3(3), Table 2308.11.4, 2404.1, 2410.1.1, 2410.1.2, 2505.1, 2505.2, 2506.2.1, 3115.8.4.2

8—22: Standard Specification for the Design of Cold-Formed Stainless Steel Structural Members

1604.3.3, 2205.1, 2211.

19—16: Structural Applications of Steel Cables for Buildings

2214.1

24—14: Flood Resistant Design and Construction

1202.4.2, 1202.4.4, 1612.2, 1612.4, 2702.1.8, 3001.3

29—05: Standard Calculation Methods for Structural Fire Protection

722.1

32—01: Design and Construction of Frost-Protected Shallow Foundations

1809.5

37 — 2017: Design Loads on Structures during Construction

1617A.1.18

41—13: [OSHPD 1 SPC-2 and SPC-4D only] Seismic Evaluation and Retrofit of Existing Buildings

1603A.2

41—17: [DSA-SS, DSA-SS/CC] Seismic Evaluation and Retrofit of Existing Buildings

1603A.2

41 — 23: [DSA-SS, DSA-SS/CC] [OSHPD 1, 1R, 2, 4 and 5] Seismic Evaluation and Retrofit of Existing Buildings

1603A.2

49—21: Wind Tunnel Testing for Buildings and Other Structures

1609.1.1

55—16: Tensile Membrane Structures

3102.2

ASHRAE ASHRAE, 180 Technology Parkway, Peachtree Corners, GA 30092

90.1—2022: Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings

1202.1

170—2021: Ventilation of Health Care Facilities

1020.6

171 — 2017: Method of Testing for Rating Seismic and Wind Restraints

1705.14.2, 1705A.14.2

ASME American Society of Mechanical Engineers, Two Park Avenue, New York, NY 10016
CMC § 100.0 Medium relevance — show source text
2025 CBC Building Code

Converted from PDF using pymupdf4llm Source: 2025 CBC Building Code.pdf Text ratio: 100.0% Conversion date: 2025-10-05 02:52:49

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on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

2025 California Building Code California Code of Regulations, Title 24, Volume 1 of Part 2

COPYRIGHT  2025

by INTERNATIONAL CODE COUNCIL, INC.

[DSA-AC] (916) 445-5827 DSAaccess@dgs.ca.gov Access for Persons with Disabilities

Structural Safety [DSA-SS, DSA-SS/CC]

Public Schools & Community Colleges, State Essential Services Buildings

State Historical Building Safety Board [SHBSB] (916) 445-7627 shbsb@dgs.ca.gov Historical Building Rehabilitation, Preservation, Restoration or Relocation

Energy Commission [CEC] energy.ca.gov Title24@energy.ca.gov (800) 772-3300 Building Energy Efficiency, Compliance Manual & Compliance Forms

Office of the State Fire Marshal [SFM]

osfm.fire.ca.gov codedevelopment@fire.ca.gov

(916) 568-3800 Fire & Life Safety

State Lands Commission [SLC]

slc.ca.gov MOTEMS.Public@slc.ca.gov (510) 741-4950 Marine Oil Terminals

State Librarian [SL]

library.ca.gov csllaw@library.ca.gov (916) 323-9843 Public Library Construction & Renovation

Structural Pest Control Board [CA] pestboard.ca.gov pestboard@dca.ca.gov (800) 737-8188 Structural Pest Control Locations

Veterinary Medical Board [CA] vmb.ca.gov vmb@dca.ca.gov (916) 515-5220 Veterinary Facilities

Department of Food and Agriculture [AGR] cdfa.ca.gov (916) 900-5004 Rendering & Collection Centers (916) 900-5064 Meat & Poultry Packing Plants (916) 900-5008 Milk & Dairy Food Safety

Department of Health Care Access and Information

Office of Statewide Hospital Planning and Development

[OSHPD 1, 1R, 2, 3, 4, 5, 6] hcai.ca.gov regsunit@hcai.ca.gov (916) 440-8300 Hospital Standards, Skilled Nursing Facility Standards & Clinic Standards

Department of Public Health [DPH]

cdph.ca.gov (Recreational Health) (916) 449-5661 Food Establishments, Organized Camps, Public Swimming Pools

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How to Distinguish Between Model Code Language and California Amendments

To distinguish between model code language and the incorporated California amendments, including exclusive California stan- dards, California amendments will appear in italics.

CMC § 62.1 Medium relevance — show source text

Controls shall be designed to coordinate operation of the natural and mechanical ventilation systems. [ASHRAE 62.1:6.4.3] D. Naturally ventilated spaces shall also include a mechanical ventilation system designed in accordance with Section 120.1(c)3. Exception 1 to Section 120.1(c)2D: Spaces not served by a space-conditioning system. Exception 2 to Section 120.1(c)2D: Spaces where natural ventilation openings complying with Section 120.1(c)2 are either permanently open or have controls that prevent the openings from being closed during periods of expected occupancy. 3. Mechanical ventilation. Occupiable spaces shall be ventilated with a mechanical ventilation system capable of providing an outdoor airflow rate to the zone ( V z ) no less than Equation 120.1-F as described below:

(Equation 120.1-F) V z = The larger of R p × P z or R a × A z

Where:

R p = 15 cubic feet per minute of outdoor airflow per person P z = The expected number of occupants. For spaces without fixed seating, the expected number of occupants shall be the expected number specified by the building designer or the default occupancy density in Table 120.1-A times the occupiable floor area of the zone, whichever is greater. For spaces with fixed seating, the expected number of occupants shall be determined in accordance with Section 1004.6 of the California Building Code. R a = The area-based minimum ventilation airflow rate in Table 120.1-A. A z = The net occupiable floor area of the ventilation zone in square feet.

Exception 2 to Section 120.1(c)3: Transfer air. The rate of outdoor air required by Section 120.1(c)3 may be provided with air transferred from other ventilated space if: A. Use of transfer air is in accordance with Section 120.1(g); and B. The outdoor air that is supplied to all spaces combined, is sufficient to meet the requirements of Section 120.1(c)3 for each space individually. 4. Exhaust ventilation. The design exhaust airflow shall be determined in accordance with the requirements in Table 120.1-B. Exhaust makeup air shall be permitted to be any combination of outdoor air, recirculated air, or transfer air.

[ASHRAE 62.1:6.5.1]

66 2025 CALIFORNIA ENERGY CODE

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NONRESIDENTIAL, HOTEL/MOTEL OCCUPANCIES, AND COVERED PROCESSES—MANDATORY REQUIREMENTS

TABLE 120.1-A—MINIMUM VENTILATION RATES	Col2	Col3	Col4	Col5
OCCUPANCY CATEGORY	MINIMUM OCCUPANT LOAD DENSITY (persons/1,000 ft2)	AREA-BASED MINIMUM VENTILATION_ Ra_ (cfm/ft2)	AIR CLASS	NOTES
Educational Facilities	Educational Facilities	Educational Facilities	Educational Facilities	Educational Facilities
Daycare (through age 4)	14	0.

CMC § 405.4.1 Medium relevance — show source text
instructions.

405.4.1 Exhaust Rate. For intermittent-controlled operations, the exhaust rate shall be not less than 100 ft [3] /min (47.2 L/s) for range hoods or 300 ft [3] /min (142 L/s) for mechanical exhaust fans including downdraft appliances. For continuous operated ventilation, the exhaust rate shall be not less than 50 ft [3] /min (23.6 L/s). 405.5 Ventilation Openings. Occupiable spaces shall be provided with a readily accessible ventilation opening openable to the outdoors. The opening shall be not less than 5 square feet (0.464 m [2] ) or 4 percent of the occupied floor area. The openable area shall be based on free, unobstructed area through the opening.

2025 CALIFORNIA MECHANICAL CODE 77

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VENTILATION AIR

406.0 Evaporative Cooling System for Health Care Facilities. [OSHPD 1, 2, 3, 4 & 5] Direct evaporative cool- ing systems where the air directly contacts the wetted surface or spray shall be limited in health facilities to nonpatient areas such as laundry rooms, and boiler or machinery rooms. Similar rooms with high heating-producing equipment will be consid- ered when specifically approved by the enforcing agency. The evaporative pads shall be a synthetic type. Filters shall be required in accordance with Tables 4-B and 4-C except utility rooms, i.e.: boiler or machinery rooms.

407.0 Ventilation System Details. [OSHPD 1, 1R, 2, 3, 4 & 5]

407.1 General.

407.1.1 All supply-air, return air, and exhaust-air sys- tems shall be mechanically operated and such systems for areas listed in Table 4-A shall be operated continu- ously. Natural ventilation through windows or other openings such as louvers will be considered as supple- mental to the required mechanical ventilation systems.

Exceptions:

(1) Natural ventilation shall not be used in airborne infection isolation rooms and protective environment

rooms.

(2) Unoccupied turndown shall be permitted in accor- dance with Section 407.7.

407.1.2 Fans serving exhaust systems shall be located at the discharge end of the system. Ductwork within the building shall be under negative pressure. The ventilation rates shown in Table 4-A shall be considered as minimum acceptable rates and shall not be construed as precluding the use of higher ventilation rates if they are required to meet design conditions. 407.1.3 Services/Systems and Utilities. (Refer to Sec- tion 1224.4.1 of the California Building Code).

407.2 Outdoor Air Intakes and Exhaust Outlets.

407.2.1 Outdoor Air Intakes. Outdoor air intakes shall be located at least 25 feet (7.62 m) from exhaust outlets of ventilating systems, combustion equipment stacks, med- ical-surgical vacuum systems, cooling towers, and areas that may collect vehicular exhaust or other noxious _fumes.
CMC § 0.0929 Medium relevance — show source text
For SI Units: 1 square foot = 0.0929 m [2], 1 cubic foot per minute = 0.0283 m [3] /min, 1 cubic foot per minute = 0.4719 L/s

405.2.1 Reduced Ventilation Air Rate. Where permitted by the Authority Having Jurisdiction, the mechanical ventilation air rate required in Section 405.2 shall be permitted to be reduced where an infiltration rate is determined in accordance with ASTM E779.

405.3 Bathroom Exhaust. A mechanical exhaust directly to the outdoors shall be provided in each room containing a bathtub, shower, or tub/shower combination. The fan shall run intermittently (on demand) or continuously. A readily accessible manual control designed to be operated as needed or an automatic control shall be provided for intermittent operations. [HCD 1 & HCD 2] Each bathroom shall also be mechanically ventilated in accordance with Division 4.5 of the California Green Building Standards Code (CALGreen).

405.3.1 Exhaust Rate. The exhaust rate shall be not less than 50 ft [3] /min (23.6 L/s) for intermittent operation and 25 ft [3] /min (11.8 L/s) for continuous operation. 405.4 Kitchen Exhaust. A mechanical exhaust system that discharges directly to the outdoors shall be provided in each kitchen. The fan shall run intermittently (on demand) or continuously. A readily accessible manual control designed to be operated as needed or an automatic control shall be provided for intermittent operations.

Exception: Recirculating systems installed in accordance with Section 516.0 and the manufacturer’s installation

instructions.

405.4.1 Exhaust Rate. For intermittent-controlled operations, the exhaust rate shall be not less than 100 ft [3] /min (47.2 L/s) for range hoods or 300 ft [3] /min (142 L/s) for mechanical exhaust fans including downdraft appliances. For continuous operated ventilation, the exhaust rate shall be not less than 50 ft [3] /min (23.6 L/s). 405.5 Ventilation Openings. Occupiable spaces shall be provided with a readily accessible ventilation opening openable to the outdoors. The opening shall be not less than 5 square feet (0.464 m [2] ) or 4 percent of the occupied floor area. The openable area shall be based on free, unobstructed area through the opening.

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VENTILATION AIR

406.0 Evaporative Cooling System for Health Care Facilities. [OSHPD 1, 2, 3, 4 & 5] Direct evaporative cool- ing systems where the air directly contacts the wetted surface or spray shall be limited in health facilities to nonpatient areas such as laundry rooms, and boiler or machinery rooms. Similar rooms with high heating-producing equipment will be consid- ered when specifically approved by the enforcing agency. The evaporative pads shall be a synthetic type. Filters shall be required in accordance with Tables 4-B and 4-C except utility rooms, i.e.: boiler or machinery rooms.
CMC § 140.4 Medium relevance — show source text
1. All other systems, including but not limited to DX cooling systems and chilled water systems that control the space temperature by modulating the airflow to the space, shall have proportional fan control such that at 50 percent air flow the power draw is no more than 30 percent of the fan power at full fan speed.
2. Systems that include an air side economizer to meet Section 140.4(e)1 shall have a minimum of two speeds of fan control during economizer operation.
Exception 1 to Section 140.4(m): Modulating fan control is not required for chilled water systems with all fan motors < 1 HP, or for evaporative systems with all fan motors < 1 HP, if the systems are not used to provide ventilation air and all indoor fans cycle with the load.

Exception 2 to Section 140.4(m): Systems serving healthcare facilities.

TABLE 140.4-I—FAN CONTROL SYSTEMS Col2 Col3

COOLING SYSTEM TYPE FAN MOTOR SIZE COOLING CAPACITY

DX cooling Any ≥ 65,000 Btu/hr

Chilled water and evaporative ≥ 1/4 HP Any

(n) Mechanical system shut-off. Any directly conditioned space with operable wall or roof openings to the outdoors shall be provided with interlock controls that disable or reset the temperature setpoint to 55°F for mechanical heating and disable or reset the temperature setpoint to 90°F for mechanical cooling to that space when any such opening is open for more than 5 minutes.

Exception 1 to Section 140.4(n): Interlocks are not required on doors with automatic closing devices.

Exception 2 to Section 140.4(n): Any space without a thermostatic control (thermostat or a space temperature sensor used to control heating or cooling to the space).

Exception 3 to Section 140.4(n): Healthcare facilities.

126 2025 CALIFORNIA ENERGY CODE

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NONRESIDENTIAL AND HOTEL/MOTEL OCCUPANCIES—PERFORMANCE AND PRESCRIPTIVE

COMPLIANCE APPROACHES FOR ACHIEVING ENERGY EFFICIENCY

(o) Exhaust system transfer air. Conditioned supply air delivered to any space with mechanical exhaust shall not exceed the greater of:
1. The supply flow required to meet the space heating or cooling load; or
2. The ventilation rate required by the authority having jurisdiction, the facility Environmental Health and Safety Department, or by Section 120.1(c)3; or
3. The mechanical exhaust flow minus the available transfer air. Available transfer air shall be from another conditioned space or return air plenums on the same floor and same smoke or fire compartment, and that at their closest point are within 15 feet of each other.
Exception 1 to Section 140.4(o): Biosafety level classified laboratories 3 or higher.

Exception 2 to Section 140.4(o): Vivarium spaces.

Exception 3 to Section 140.4(o): Spaces that are required by applicable codes and standards to be maintained at a positive pressure differential relative to adjacent spaces.

Exception 4 to Section 140.4(o): Spaces where the highest amount of transfer air that could be used for exhaust makeup may exceed the available transfer airflow rate and where the spaces have a required negative pressure relationship.

Exception 5 to Section 140.4(o): Healthcare facilities.
CMC § 503.5 Medium relevance — show source text
(1) DX and chilled-water cooling units that control the capacity of the mechanical cooling directly based on space temperature shall have a minimum of two stages of fan control. Low or minimum speed shall not exceed 66 percent of full speed. At low or minimum speed, the fan system shall draw no more than 40 percent of the fan power at full fan speed. Low or minimum speed shall be used during periods of low cooling load and ventilation-only operation.

(2) All other units, including DX cooling units and chilled-water units that control the space temperature by modulating the airflow to the space, shall have modulating fan control. Minimum speed shall not exceed 50 percent of full speed. At minimum speed, the fan system shall draw no more than 30 percent of the power at full fan speed. Low or minimum speed shall be used during periods of low cooling load and ventilation-only operation.

(3) Units that include an air economizer to meet the requirements of Section E 503.5 through Section E 503.5.4.1 shall have a minimum of two speeds of fan control during economizer operation.

Exceptions:

(1) Modulating fan control shall not be required for chilled-water and evaporative cooling units with less than 1 hp (0.7 kW) fan motors where the units are not used to provide ventilation air and where the indoor fan cycles with the load.

(2) Where the volume of outdoor air required to meet the ventilation requirements of Chapter 4 or ASHRAE 62.1 at low speed exceeds the air that would be delivered at the speed defined in Section E 503.5.6.2(1), or Section E 503.5.6.2(2), then the minimum speed shall be selected to provide the required ventilation air.

[ASHRAE 90.1:6.5.3.2.1]

TABLE E 503.5.6.2

FAN AIRFLOW CONTROL

[ASHRAE 90.1: TABLE 6.5.3.2.1]

COOLING SYSTEM TYPE FAN MOTOR SIZE,
(hp) MECHANICAL
COOLING CAPACITY,
(Btu/h)

DX cooling Any ≥65 000

Chilled-water and evapo-
rative cooling
≥1⁄4
Any

For SI units: 1000 British thermal units per hour = 0.293 kW, 1 horsepower = 0.746 kW, 1 cubic foot per minute = 0.00047 m [3] /s

E 503.5.6.2.1 VAV Static Pressure Sensor Location. Static pressure sensors used to control VAV fans shall be located such that the controller setpoint is not more than 1.2 inches water column (0.30 kPa). Where this results in the sensor being located downstream of major duct splits, sensors shall be installed in each major branch to ensure that static pressure is maintained in each.

Exception: Systems that are in accordance with Section E 503.5.6.2.2. [ASHRAE 90.1:6.5.3.2.2]
California Mechanical Code Medium relevance — show source text
OF VENT REQUIRED (inches)| |SIZE OF
SOIL OR
WASTE
STACK
(inches)|FIXTURE
UNITS
CONNECTED|11⁄4|11⁄2|2|21⁄2|3|4|5|6|8| |SIZE OF
SOIL OR
WASTE
STACK
(inches)**|FIXTURE
UNITS
CONNECTED|MAXIMUM LENGTH OF VENT (feet)|MAXIMUM LENGTH OF VENT (feet)|MAXIMUM LENGTH OF VENT (feet)|MAXIMUM LENGTH OF VENT (feet)|MAXIMUM LENGTH OF VENT (feet)|MAXIMUM LENGTH OF VENT (feet)|MAXIMUM LENGTH OF VENT (feet)|MAXIMUM LENGTH OF VENT (feet)|MAXIMUM LENGTH OF VENT (feet)| |11⁄2|8|50|150|––|––|––|––|––|––|––| |2|12|30|75|200|––|––|––|––|––|––| |2|20|26|50|150|––|––|––|––|––|––| |21⁄2|42|––|30|100|300|––|––|––|––|––| |3|10|––|30|100|100|600|––|––|––|––| |3|30|––|––|60|200|500|––|––|––|––| |3|60|––|––|50|80|400|––|––|––|––| |4|100|––|––|35|100|260|1000|––|––|––| |4|200|––|––|30|90|250|900|––|––|––| |4|500|––|––|20|70|180|700|––|––|––| |5|200|––|––|––|35|80|350|1000|––|––| |5|500|––|––|––|30|70|300|900|––|––| |5|1100|––|––|––|20|50|200|700|––|––| |6|350|––|––|––|25|50|200|400|1300|––| |6|62
CMC § 926.5 Medium relevance — show source text
926.5 Bypass Valves. Where an integral bypass system is not provided as a part of the pool heater, a bypass line and valve shall be installed between the inlet and outlet piping for use in adjusting the flow of water through the heater. [NFPA 54:10.19.5]

926.6 Venting. A pool heater listed for outdoor installation shall be installed with the venting means supplied by the manufacturer and in accordance with the manufacturer’s installation instructions. [NFPA 54:10.19.6]

927.0 Refrigerators.

927.1 Application. Refrigerators shall be listed in accordance with CSA/ANSI Z21.19/CSA 1.4. [NFPA 54:10.20.1]

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212 2025 CALIFORNIA MECHANICAL CODE

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INSTALLATION OF SPECIFIC APPLIANCES

enclosed by more than two vertical wall surfaces, a hood and gravity ventilation duct shall be installed in accordance with Section 930.5.2, Section 930.5.3, and Section 603.13.6.

931.0 Outdoor Open Flame Decorative Appliances. 931.1 General. Permanently fixed in place outdoor open flame decorative appliances shall be installed in accordance with Section 931.1.1 and Section 931.1.2. [NFPA 54:10.30] 931.1.1 Application. Outdoor open flame decorative appliances shall be listed in accordance with ANSI Z21.97/CSA 2.41 and shall be installed in accordance with the manufacturer’s installation instructions. [NFPA 54:10.30.1] 931.1.2 Connection to the Piping System. The connection to the gas piping system shall be in accordance with Section 1312.1(1), Section 1312.1(2), Section 1312.1(4), or Section 1312.1(5). [NFPA 54:10.30.2]

932.0 Evaporative Cooling Systems. 932.1 General. Evaporative cooling systems, including air ducts and fire dampers that are a portion of an evaporative cooling system, shall be in accordance with Section 932.2 through Section 932.4.3. Evaporative cooling systems shall be provided with outside air as specified for cooling systems in Section 403.0.

932.2 Location. Evaporative cooling systems shall be installed so as to minimize the probability of damage from an external source.

932.3 Access, Inspection, and Repair. Evaporative coolers shall be accessible for inspection, service, and replacement without removing permanent construction. 932.4 Installation. An evaporative cooler supported by the building structure shall be installed on a level base and shall be secured directly or indirectly to the building structure, to prevent displacement of the cooler. 932.4.1 Modifications to the Supporting Struc- ture. Modifications made to the supporting framework of buildings as a result of the installation shall be in accordance with the requirements of the building code. Openings in exterior walls shall be flashed in an approved manner in accordance with the requirements of the building code. **932.4.2 On the Ground.
California Mechanical Code Medium relevance — show source text

2
5
8|37
39
NA
NA|83
56
NA
NA|50
39
37
33|58
59
77
90|164
108
102
95|93
75
69
64|83
83
107
122|273
176
168
161|154
119
114
107|123
121
151
175|412
261
252
243|234
179
171
163|161
155
193
223|580
363
352
342|319
246
235
225| |10|0
2
5
10|37
39
52
NA|87
61
56
NA|53
41
39
34|57
59
76
97|174
117
111
100|99
80
76
68|82
82
105
132|293
193
185
171|165
128
122
112|120
119
148
188|444
287
277
261|254
194
186
171|158
153
190
237|628
400
388
369|344
272
261
241| |15|0
2
5
10
15|36
38
51
NA
NA|93
69
63
NA
NA|57
47
44
39
NA|56
57
75
95
NA|190
136
128
116
NA|111
93
86
79
72|80
80
102
128
158|325
225
216
201
186|186
149
140
131
124|116
115
144
182
220|499
337
326
308
290|283
224
217
203
192|153
148
182
228
272|713
473
459
438
418|388
314
298
284
269| |20|0
2
5
California Mechanical Code Medium relevance — show source text

2
5
10
15|36
38
51
NA
NA|93
69
63
NA
NA|57
47
44
39
NA|56
57
75
95
NA|190
136
128
116
NA|111
93
86
79
72|80
80
102
128
158|325
225
216
201
186|186
149
140
131
124|116
115
144
182
220|499
337
326
308
290|283
224
217
203
192|153
148
182
228
272|713
473
459
438
418|388
314
298
284
269| |20|0
2
5
10
15
20|35
37
50
NA
NA
NA|96
74
68
NA
NA
NA|60
50
47
41
NA
NA|54
56
73
93
NA
NA|200
148
140
129
NA
NA|118
99
94
86
80
NA|78
78
100
125
155
186|346
248
239
223
208
192|201
165
158
146
136
126|114
113
141
177
216
254|537
375
363
344
325
306|306
248
239
224
210
196|149
144
178
222
264
309|772
528
514
491
469
448|428
344
334
316
301
285| |30|0
2
5
California Mechanical Code Medium relevance — show source text
600
18 900
17 600
16 500
15 600| |125
150
175
200
250|125
150
175
200
250|105
95
88
82
72|217
197
181
168
149|442
400
368
343
304|772
700
644
599
531|1100
992
913
849
753|2340
2120
1950
1810
1610|4210
3820
3510
3270
2900|6640
6020
5540
5150
4560|13 800
12 500
11 500
10 700
9510| |300
350
400
450
500|300
350
400
450
500|66
60
56
53
50|135
124
116
109
103|275
253
235
221
209|481
442
411
386
365|682
628
584
548
517|1460
1340
1250
1170
1110|2620
2410
2250
2110
1990|4140
3800
3540
3320
3140|8610
7920
7370
6920
6530| |550
600
650
700
750|550
600
650
700
750|47
45
43
41
40|97
93
89
86
82|198
189
181
174
168|346
330
316
304
293|491
469
449
431
415|1050<b
California Mechanical Code Medium relevance — show source text
21
20|47
46
44
43
42|96
93
90
88
85|168
163
158
153
149|239
231
224
217
211|510
493
478
464
452|917
888
861
836
813|1450
1400
1360
1320
1280|3010
2920
2830
2740
2670| |1100
1200
1300
1400
1500|1100
1200
1300
1400
1500|19
18
18
17
16|40
38
36
35
34|81
77
74
71
68|142
135
129
124
120|201
192
183
176
170|429
409
392
376
363|772
737
705
678
653|1220
1160
1110
1070
1030|2540
2420
2320
2230
2140| |1600
1700
1800
1900
2000|1600
1700
1800
1900
2000|16
15
15
14
14|33
31
30
30
29|66
64
62
60
59|116
112
108<b
California Mechanical Code Medium relevance — show source text
r>1060
1030
1000|1790
1730
1680
1630
1580|3720
3600
3490
3390
3300| |1100
1200
1300
1400
1500|1100
1200
1300
1400
1500|24
23
22
21
20|49
47
45
43
42|100
95
91
88
85|175
167
160
153
148|248
237
227
218
210|530
505
484
465
448|954
910
871
837
806|1500
1430
1370
1320
1270|3130
2990
2860
2750
2650| |1600
1700
1800
1900
2000|1600
1700
1800
1900
2000|19
19
18
18
17|40
39
38
37
36|82
79
77
74
72|143
138
134
130
126|202
196
190
184
179|432
419
406
394
383|779
753
731
709
690|1230
1190
1150
1120
1090|2560
2470
2400<
California Mechanical Code Medium relevance — show source text
0
1450
1410
1370|2430
2350
2280
2220
2160|5070
4900
4750
4620
4490| |1100
1200
1300
1400
1500|1100
1200
1300
1400
1500|32
31
30
28
27|67
64
61
59
57|136
130
124
120
115|238
227
217
209
201|338
322
309
296
286|721
688
659
633
610|1300
1240
1190
1140
1100|2050
1950
1870
1800
1730|4270
4070
3900
3740
3610| |1600
1700
1800
1900
2000|1600
1700
1800
1900
2000|26
26
25
24
23|55
53
51
50
48|111
108
104
101
99|194
188
182
177
172|276
267
259
251
244|589
570
553
537
522|1060
1030
1000
966
940|1670
1620
1570
1520
1480|34

TABLE 140.4-I—FAN CONTROL SYSTEMS	Col2	Col3
COOLING SYSTEM TYPE	FAN MOTOR SIZE	COOLING CAPACITY
DX cooling	Any	≥ 65,000 Btu/hr
Chilled water and evaporative	≥ 1/4 HP	Any

COOLING SYSTEM TYPE	FAN MOTOR SIZE, (hp)	MECHANICAL COOLING CAPACITY, (Btu/h)
DX cooling	Any	≥65 000
Chilled-water and evapo- rative cooling	≥1⁄4	Any

Frequently asked questions

Can I size a natatorium ventilation system using CMC Table 402.1 rates?

No. The CMC § 401.2 requires natatorium ventilation to comply with the Uniform Swimming Pool, Spa and Hot Tub Code (USPSHTC); do not substitute generic CMC occupancy rates for pool spaces — follow the USPSHTC text and any California amendments referenced therein .

Are direct evaporative coolers allowed in operating rooms or patient rooms?

No. § 406.0 restricts direct evaporative cooling (air contacting wetted pads/spray) to nonpatient areas such as laundries and boiler/machinery rooms; they are not permitted in patient‑care spaces without explicit approval by the enforcing agency .

If I put an evaporative cooler in a hospital utility room, do I need filters?

Yes — the code requires filtration per Tables 4‑B and 4‑C for evaporative systems in health-care buildings, except where the tables specifically exempt utility rooms (e.g., laundries) — verify the exact table entries and show filters on the plans as required by § 406.0 .

My indoor pool enclosure is 550 ft² — does the CMC require energy recovery on the dehumidifier?

Yes — Appendix E (E 503.5.10.4) of the CMC requires indoor pool dehumidifiers serving natatoriums with a heated pool over 500 ft² to include one of several specified energy‑recovery options; follow the Appendix E language when selecting the dehumidifier .

Who decides if an evaporative cooler may serve a space that is “similar” to a boiler room?

The enforcing agency has authority to approve evaporative cooling in rooms that are “similar” to boiler/machinery rooms on a case‑by‑case basis; document the justification and obtain written approval per § 406.0 .

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Related in the CMC

What ventilation rate procedure applies to dwelling units (405.0 series)?

When is combustion air or makeup air required for appliances and how to size it?

How does the CMC Ventilation Air interact with the California Energy and Building Codes?

Special occupancies, residential ventilation, and combustion/makeup air cross‑references

California Mechanical Code