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Glossary

Mastic

Heavy-consistency compound that may remain adhesive and pliable with age. Typically an airtight, waterproof compound that is applied to exterior walls and roof surfaces or used to provide a robust and durable air seal to air duct distribution systems.

Related terms: Adhesive, Sealant

Related resource: Info-603: Duct Sealing; Info-801: What's Wrong With This Practice? Using Unsealed Wall Cavities or Panned Floor Joists as Return Plenum