TL;DR
Duct sealing mastic is a thick, water-based sealant brushed or gloved onto duct joints, seams, and boot connections, where it cures into a flexible, permanent air barrier. It is the code-preferred method for sealing ductwork — UL 181B-M rated — because cloth duct tape dries out and peels within a few years.
What it means
Duct sealing mastic is a thick, water-based sealant brushed or gloved onto duct joints, seams, and boot connections, where it cures into a flexible, permanent air barrier. It is the code-preferred method for sealing ductwork — UL 181B-M rated — because cloth duct tape dries out and peels within a few years. Crews often embed fiberglass mesh in the mastic across gaps wider than about a quarter inch for reinforcement.
Where it sits in the glossary
Duct sealing mastic is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
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