IMC · 2021 International Mechanical Code

§504.1 · Installation

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

Plain-English explainer

504.1 says exhaust systems are independent of other systems and discharge to the outdoors through listed ducts and terminations. The drafter cites it when drafting a bathroom, dryer, or commercial hood that needs its own run — no sharing with supply, no shared returns.

Why inspectors flag this

A dryer or bath tied into a supply run is a classic 504.1 violation; surfacing this rule on the draft lets the contractor dis-connect before the rough-in walk-through.

As quoted in the code: Exhaust systems are independent of other systems and discharge to the outdoors through listed ducts and terminations.

See all codes that cite this trade

Browse the full International Mechanical Code index for one place to read every section the drafter is allowed to quote. See all codes →

See pricing

See every code, every jurisdiction — without the binder.

Trussmark turns job-site photos and voice notes into code-cited permit drafts the inspector can verify on the spot. Pick the plan that fits your shop and we will size the rest with you. Already cited this code in IMC 2021? Drop your email and we'll size the rest of the permit draft for you. See pricing →

See pricing