Apprentice answer

How do I find the duct elevations (Bottom of Duct / BOD) on the mechanical plans

2nd YearPrint Reading, RFIs & Trade CoordinationCheck first

Look for an elevation note tag stamped directly along the specific duct run line on the floor plan drawing. It will typically be noted as BOD = 11'-6" (Bottom of Duct) or TOD = 12'-0" (Top of Duct). This tells you the absolute installation height measured from the finished floor line up to the flat metal face.

Ask a jobsite question Back to Print Reading, RFIs & Trade Coordination

Plain-English answer

Field checklist

Look for an elevation note tag stamped directly along the specific duct run line on the floor plan drawing. It will typically be noted as BOD = 11'-6" (Bottom of Duct) or TOD = 12'-0"...

Ask Foreman

Hey boss, I’m checking blueprint reading: How do I find the duct elevations (Bottom of Duct / BOD) on the mechanical plans? I found the likely issue and want to verify the next step before I lock it in. Do you want me to adjust it now or check the drawing/detail first?

Verify before acting

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.

Related questions in this category

What does a "hash mark" with a number inside a duct run mean on a blueprint?2nd Year What is the symbol for a drop (duct going down) versus a rise (duct going up)?2nd Year How do I cross-reference the mechanical plan with the reflected ceiling plan (RCP)?2nd Year What does it mean when the print says "field verify" for a dimension?2nd Year What does "NIC" mean when it's stamped next to a piece of equipment?2nd Year Who has the right-of-way in a ceiling plenum: Ductwork, Gravity Plumbing, or Sprinklers?3rd Year