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Earlier editions: 20222019

Chapter 4 — RESIDENTIAL MANDATORY MEASURES

4.506 Indoor Air Quality and Exhaust — 2025 California Green Building Standards Code

California Green Building Standards Code (Title 24, Part 11) · 2025 edition · updated 2026-09-25 · California

CBSC: official editions, supplements and errata

Cite as: 2025 California Green Building Standards Code (Title 24, Part 11) § 4.506 · Effective January 1, 2026 · Official source: Building Standards Commission

4.506.1 Bathroom exhaust fans. Each bathroom shall be mechanically ventilated and shall comply with the following:

  1. Fans shall be ENERGY STAR compliant and be ducted to terminate outside the building.
  2. Unless functioning as a component of a whole house ventilation system, fans must be controlled by a humidity control. a. Humidity controls shall be capable of adjustment between a relative humidity range of ≤ 50 percent to a maximum of 80 percent. A humidity control may utilize manual or automatic means of adjustment. b. A humidity control may be a separate component to the exhaust fan and is not required to be integral (i.e., built-in).

Notes:

  1. For the purposes of this section, a bathroom is a room which contains a bathtub, shower or tub/shower combination.
  2. Lighting integral to bathroom exhaust fans shall comply with the California Energy Code.

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▸Contents — California Green Building Standards Code (Title 24, Part 11)
California Green Building Standards Code (Title 24, Part 11)

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