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Chapter 4 — RESIDENTIAL MANDATORY MEASURES

Section 4.506 — INDOOR AIR QUALITY AND EXHAUST

2025 California Green Building Standards Code (Title 24, Part 11) · 2025 edition · updated 2026-07-25 · California

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 — 2025 California Green Building Standards Code (Title 24, Part 11)
2025 California Green Building Standards Code (Title 24, Part 11)
  1. Chapter 1 — ADMINISTRATION
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GREEN BUILDING
  4. Chapter 4 — RESIDENTIAL MANDATORY MEASURES
  5. Chapter 4 — RESIDENTIAL MANDATORY MEASURES
  6. Chapter 4 — RESIDENTIAL MANDATORY MEASURES
  7. Chapter 4 — RESIDENTIAL MANDATORY MEASURES
  8. ▸ Chapter 4 — RESIDENTIAL MANDATORY MEASURES
    Overview
    1. Section 4.501 — GENERAL
    2. Section 4.502 — DEFINITIONS
    3. Section 4.503 — FIREPLACES
    4. Section 4.504 — POLLUTANT CONTROL
    5. Section 4.505 — INTERIOR MOISTURE CONTROL
    6. Section 4.506 — INDOOR AIR QUALITY AND EXHAUST
    7. Section 4.507 — ENVIRONMENTAL COMFORT
    8. Section 4.508 — OUTDOOR AIR QUALITY
  9. Chapter 5 — NONRESIDENTIAL MANDATORY MEASURES
  10. Chapter 5 — NONRESIDENTIAL MANDATORY MEASURES
  11. Chapter 5 — NONRESIDENTIAL MANDATORY MEASURES
  12. Chapter 5 — NONRESIDENTIAL MANDATORY MEASURES
  13. Chapter 5 — NONRESIDENTIAL MANDATORY MEASURES
  14. Chapter 6 — REFERENCED ORGANIZATIONS AND STANDARDS
  15. Chapter 7 — INSTALLER AND SPECIAL INSPECTOR QUALIFICATIONS
  16. Chapter 8 — COMPLIANCE FORMS, WORKSHEETS AND REFERENCE MATERIAL

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