Exposed rectangular duct
Architectural horizontal run
Before you start
- Confirm the visible reference plane, bottom elevation, joint type, cleat direction, flange appearance, support finish, reinforcement, and architectural acceptance standard.
- Inspect the bottom and side panels for oil-canning, scratches, dents, bowed flanges, crooked reinforcement, and shop residue.
- Decide which face is the visual control face before lifting.
- Stage clean clamps, drift pins, padded supports, and finish-safe handling equipment.
Tools and materials
Exposed rectangular duct, TDC/TDF or approved clean-flange hardware, gasket, corners, cleats, approved fasteners and sealant, clean drift pins and clamps, architectural trapezes or cables, laser, level, clean gloves, and surface-cleaning materials.
Lay it out
- Set a continuous laser reference for the visible bottom plane and run centerline.
- Lay out joints, trapezes, seams, fittings, and reinforcement in a consistent visual sequence.
- Keep supports clear of flange joints and major visible features.
Set and support it
- Install and level the architectural supports before lifting sections.
- Support the duct body, not the flange joint.
- Use enough lift control to prevent panel dents and flange damage.
Make the connection
- 1
Set both sections to the same bottom plane and side alignment.
- 2
Install gasket and corner components using the approved joint method.
- 3
Drift and clamp the joint without pulling a racked section into place.
- 4
Install bolts and cleats evenly and in a consistent orientation.
- 5
Complete only the required sealing while protecting the exposed face.
- 6
Load the supports and sight the bottom and side planes.
- 7
Remove labels, adhesive, sealant smears, and fingerprints.
Check the install
- The bottom plane reads straight through the full run.
- Joints are square and flange lines remain consistent.
- Cleats, bolts, reinforcement, and supports look organized.
- No visible oil-canning, dent, dirt, or sealant smear exceeds the accepted condition.
- The joint carries no support load.
Common mistakes
- Aligning only the top because it is easy to see from the lift.
- Using cleats or bolts to force a crooked flange together.
- Changing cleat direction or hanger style through the room.
- Accepting visibly poor fabrication because the duct is technically sealed.
Stop and ask
Stop if fabrication quality is visibly unacceptable, flanges are bowed or damaged, the bottom plane cannot be held, or the support and joint layout conflicts with the architectural intent.