Not understanding dashed/hidden lines for duct above/below

Dashed lines can mean hidden/above/below, existing, demo, future, or another drawing convention. The legend controls - but if the legend is unclear, ask before installing from the line style alone.

Stop if

• What does this dashed/hidden line mean on this sheet?

Watch out

• Do not treat dashed lines like visible duct without checking the legend.

Check

• Find the line type legend on the sheet or general notes.
• Check whether dashed means hidden/above/below, existing, demo, future, or centerline on this set.
• Trace the dashed run to solid connections, notes, demo clouds, or section markers.
• Compare mechanical plan to demo plan, RCP, and sections if needed.
• Ask before treating a dashed line as new duct to install.

Steps

• Find the line type legend on the sheet or general notes.
• Check whether dashed means hidden/above/below, existing, demo, future, or centerline on this set.
• Trace the dashed run to solid connections, notes, demo clouds, or section markers.
• Compare mechanical plan to demo plan, RCP, and sections if needed.
• Ask before treating a dashed line as new duct to install.

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