IPC · 2024 International Plumbing Code
§903 · Vent sizing and termination
Effective in IPC 2024.
Plain-English explainer
903 sizes vent piping by the fixture units on the served drain, sizes the vent at no less than the trap it serves, and terminates it above the roof line at the height and offset the section requires so the open end does not admit snow, foul air, or condensate back into the building. The drafter cites it for any permit that adds or relocates a vent terminal.
Why inspectors flag this
A vent terminal below a window, near a forced-air inlet, or below the minimum height is the canonical 903 red-tag; the drafter lifts the rule so the rough-in terminal matches before the inspector walks the roof.
As quoted in the code: Vent piping is sized by the fixture units on the served drain, sized at no less than the trap it serves, and terminates above the roof line at the height and offset the section requires so the open end does not admit snow, foul air, or condensate back into the building.
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