What is the proper way to set a curb adapter when replacing an old RTU

Plain-English answer

Clean the top flange of the existing old roof curb thoroughly and remove all degraded old foam gasket material.

Apply a thick, continuous bead of butyl caulking or heavy 1 2 1 -inch foam gasket tape around the entire perimeter of the old curb.

Lower the heavy custom steel curb adapter directly over the old curb using a crane, aligning the internal supply and return air drop openings perfectly. Screw or weld the adapter securely to the old curb before setting the new RTU on top.

Field checklist

• Stop and verify the approved detail, manufacturer instructions, foreman direction, and project specs before touching it.
• Clean the top flange of the existing old roof curb thoroughly and remove all degraded old foam gasket material.
• Apply a thick, continuous bead of butyl caulking or heavy 1 2 1 -inch foam gasket tape around the entire perimeter of the old curb.
• Lower the heavy custom steel curb adapter directly over the old curb using a crane, aligning the internal supply and return air drop openings perfectly. Screw or weld the adapter...

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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.

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