S-and-Drive Square Duct · Sealing
Seal S-and-drive joint
Low-pressure joint
Task typeSealing
Tools / equipmentApproved sealant, brush, gloves
Before you start
- Confirm the required seal class, approved sealant, surface preparation, and cure conditions.
- Complete and inspect the mechanical S-and-drive joint first.
- Keep duct surfaces clean, dry, and free of oil, dust, loose rust, and insulation debris.
Lay it out
- Identify exactly which transverse-joint areas require sealing: corners, entire perimeter, seams, or fastener penetrations.
- Plan access to the hidden side before nearby work blocks it.
Set and support it
- Ensure the joint is stable and not moving under load.
- Correct any sagging support before sealing.
Make the connection
- 1
Inspect S-cleats, drives, corners, and end treatment.
- 2
Repair any mechanical gap or loose component.
- 3
Clean the sealant bond area.
- 4
Apply the approved material in a continuous bead or coating at the specified locations.
- 5
Tool the seal without pushing excess into the airflow.
- 6
Allow required cure or protection before insulation, testing, or startup.
Check the install
- Sealant is continuous with no pinhole or skipped corner.
- The mechanical joint is complete beneath the seal.
- Material adheres to clean metal and is not smeared over dirt.
- No excess blocks the duct opening or creates an uninspectable blob.
Common mistakes
- Using sealant to replace a missing drive or open corner.
- Applying over dust, oil, water, or uncured previous material.
- Sealing only the visible side.
- Covering the joint before cure or inspection.
Stop and ask
Stop if the approved sealant or seal class is unknown, surfaces are wet/contaminated, or the mechanical joint is not complete.