IMC · 2021 International Mechanical Code

§906.1 · Clearances

Effective in IMC 2021 · IMC 2024 SE Wisconsin · IMC 2024 NW Indiana.

Plain-English explainer

906.1 says the clearances listed by the manufacturer in the installation instructions are kept and not reduced by adjoining construction. The drafter cites it for any project where a furnace, water heater, or boiler has tight side clearances that a finished wall might encroach on.

Why inspectors flag this

A built-in closet that trims three inches off a furnace side is the canonical 906.1 failure; surfacing the rule on the draft forces the layout decision before the rough-in walk-through.

As quoted in the code: The clearances listed by the manufacturer in the installation instructions are kept and not reduced by adjoining construction.

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