506.3 Penetrations — 2025 California Mechanical Code
California Mechanical Code (Title 24, Part 4) · 2025 edition · updated 2026-09-25 · 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) § 506.3 · Effective January 1, 2026 · Official source: Building Standards Commission
Exhaust ducts shall not pass through fire walls. {NFPA 91:4.2.11} 506.3.1 Fire Barriers. Exhaust ducts passing through a fire barrier having a fire resistance rating of 2 hours or greater shall meet one of the following specifications: (1) Wrapped or encased with listed or approved materials having a fire resistance rating equal to the fire
barrier for 10 feet (3048 mm) of the duct on each side of the fire barrier including duct supports within this span. (2) Constructed of materials and supports having a minimum fire resistance rating equal to the fire barrier. (3) Enclosed with a shaft that is constructed of material having a fire resistance rating equal to the fire barrier for 10 feet (3048 mm) of the duct on each side of the fire barrier with no inlets to the duct within this distance, and the duct entry into and exit from the shaft is protected in accordance with Section 506.3.2. [NFPA 91:4.2.12]
106 2025 CALIFORNIA MECHANICAL CODE
EXHAUST SYSTEMS
506.3.2 Protection. Exhaust ducts passing through fire barriers of any fire resistance rating shall be protected by sealing the space around the duct with listed or approved fire stopping having a fire resistance rating equal to the fire resistance rating of the fire barrier.
[NFPA 91:4.2.13]
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