Chapter 3 — GENERAL REGULATIONS
311.1 Source — 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) § 311.1 · Effective January 1, 2026 · Official source: Building Standards Commission
A heating or cooling air system shall be provided with return air, outside air, or both. A heating or cooling air system regulated by this code and designed to replace required ventilation shall be arranged to discharge into a conditioned space not less than the amount of outside air specified in Chapter 4.
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