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

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.

['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.']

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.

Steps

• 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"...

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