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More about Tight Duct Sealing


A properly sealed heating and cooling duct system can:

  • Reduce utility bills by up to 20%
  • Increase comfort throughout the home
  • Improve IAQ by reducing moisture, dust, and pollen

As conditioned air escapes ducts supplying heating and cooling, occupants need to run systems longer to create a comfortable living space. 

Poorly sealed return ducts in unconditioned spaces can potentially draw in contaminated air and spread contaminants throughout the house.


  1. All dust leaks, connections, and plenums shall be sealed with UL-approved mastic, UL 181 tape, or equivalent. 
  2. For additional strength with seams that are wider than 1/8 inch, cover the gap with fiberglass mesh tape, then apply the mastic. 
  3. Regular cloth-backed duct tape should not be used because it can dry out and fail quickly.