905.2 Clearances — 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) § 905.2 · Effective January 1, 2026 · Official source: Building Standards Commission

The installation of duct furnaces shall

comply with the following clearance requirements:

(1) Listed duct furnaces shall be installed with clearances of not less than 6 inches (152 mm) between adjacent walls, ceilings, and floors of combustible material and the furnace draft hood. Furnaces listed for installation at lesser

clearances shall be installed in accordance with their list ings and the manufacturer’s installation instructions. In no case shall the clearance be such as to interfere with

combustion air and accessibility.

(2) Unlisted duct furnaces shall be installed with clearances to combustible material in accordance with the clear ances specified for unlisted furnaces and boilers in Table 904.3.2. Combustible floors under unlisted duct furnaces

shall be protected in an approved manner.

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▸Contents — California Mechanical Code (Title 24, Part 4)

California Mechanical Code (Title 24, Part 4)

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