Index — M
California Mechanical Code (Title 24, Part 4) · 2025 edition · updated 2026-10-23 · 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) · Effective January 1, 2026 · Official source: Building Standards Commission
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MACHINERY
Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215.0
MACHINERY ROOM, REFRIGERATION
Definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215.0
Detectors and alarms . . . . . . . . . . . . . . . . . . . . 1106.2.9
Equipment and controls in. . . . . . . . . . . . . . . . . . 1108.0
Ventilation of . . . . . . . . . . . . . . . . . . . 1106.2.7, 1106.2.8
Where required . . . . . . . . . . . . . . . . . . . . . . . . . . 1106.0
MAKEUP AIR . . . . . . . . . . . . . . . . . . . . . . (see Air, Makeup)
MARKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.1.1
MASONRY, CHIMNEYS . . . . . . . . . (see Chimney, masonry)
MATERIALS
Alternate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.2
For construction of
hoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.3
For piping, containers, and valves of
refrigeration systems . . . . . . . . . . . . . . . . . . . . 1109.1
For ducts . . . . . . . . . . . . . . . . . . . 506.1, 510.5.1, 602.0
For fuel piping. . . . . . . . . . . . . . . . . . . . 1308.0, D 109.0
For piping, tubing
and fittings hydronics . . . . . . . . . 1210.0, Table 1210.1
For vent connectors. . . . . . . . . . . 802.10.1.1–802.10.1.4
MECHANICAL
Combustion air supply. . . . . . . . . . . . . . . 701.9, E 502.6
Equipment Schedules [OSHPD] . . . . . . . . . . . . . 323.0
Exhaust system. . . . . . . . . . . . . . . . . . . . . . . . . . . 505.1
Ventilating system . . . . . . . . . . . 402.3, 1106.7, E 502.6,
E 605.1.2, Table E 502.6
MECHANICAL EXHAUSTING FOR
Bathrooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E 605.2
Low-rise residential dwelling . . . . . . . . . . . . . . E 605.1.3
Product conveying. . . . . . . . . . . . . . . . . . . . . . . . . 505.0
Refrigeration . . . . . . . . . . . . . . . . . . . . 1105.5.2, 1106.0,
MECHANICAL JOINTS . . . . . . . . . . . . . . . . . . . . (see Joints
and connections)
MECHANICAL PERMIT FEE . . . . . . . . . 104.5, Table 104.5
MECHANICAL SYSTEMS
Application to existing . . . . . . . . . . . . . . . . . . . . . . 102.2
In elevator shaft. . . . . . . . . . . . . . . . . . . . . . . . . . . 305.4
METAL
Chimneys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 802.5.2
Ducts. . . . . . . . . . . . . . . . . . . . . . . . 506.1, 602.5, 603.3
METER, GAS . . . . . . . . . . . . . . . . . . . . . . . . 1308.5, D 104.0
METHODS OF CONSTRUCTION,
ALTERNATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.2
MINIMUM REQUIREMENTS
Purpose of Code . . . . . . . . . . . . . . . . . . . . . . . . . . 101.3
MINIMUM STANDARDS . . . . . . . . . . . . . . . . . . . . . . . 302.1
MOBILE HOME PARKS
FUEL GAS EQUIPMENT
AND INSTALLATION . . . . . . . . . . . . . . . . . . . . . D 101.1
MOTORS, FANS, AND FILTERS . . . . . . . . . . . . . . . . . 503.0
MULTIPLE-ZONE SYSTEM . . . . . . . . . . . . . . . . . . . . . 404.0
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