Large Duct Gap Needs a Mechanical Fix or Approved Reinforcement
A wide or moving gap is not automatically a “more mastic” problem. Confirm whether the joint needs to be re-fit, fastened, patched, or reinforced before sealing.
Do not bridge a structural or moving gap with a thick glob of sealant and call it finished.
Check
Measure and photograph the gap
Check whether the metal moves under light hand pressure
Verify the joint, seam, or patch detail
Confirm whether approved mesh or reinforcement is required by the sealant system
Clean and dry the surface before any approved repair
Steps
Measure and photograph the gap
Check whether the metal moves under light hand pressure
Verify the joint, seam, or patch detail
Confirm whether approved mesh or reinforcement is required by the sealant system
Clean and dry the surface before any approved repair
Say this to your foreman
This gap is about [size] at [location] and the metal [moves/does not move]. Do you want it mechanically corrected or patched before we use the approved mesh-and-sealant system?