Who has the right-of-way in a ceiling plenum: Ductwork, Gravity Plumbing, or Sprinklers?

Gravity Plumbing (Sewer/Waste Mains) & Roof Drains: Absolute first priority. They must slope continuously at a precise angle to function and cannot easily rise or fall over obstacles.

['Gravity Plumbing (Sewer/Waste Mains) & Roof Drains: Absolute first priority. They must slope continuously at a precise angle to function and cannot easily rise or fall over obstacles.', 'Large Sheet Metal Ductwork: Second priority. It is bulky and requires massive paths, but can accommodate planned offsets, drops, and transitions around structural obstacles.', 'Pressurized Fire Sprinkler Lines & Electrical Conduits: Lowest layout priority. They can easily loop, bend, and drop over or under other major system runs without affecting performance.']

Stop if

• Use this as training guidance. The foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, and AHJ/code requirements always control the final answer.

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