Highlights: Standard tape fails quickly: Never use conventional duct tape; only use UL-listed aluminum foil tape or mastic sealant, which withstand temperature changes without drying out or peeling. Leaky systems waste thirty percent of air: Gaps in your network allow significant amounts of conditioned air to escape into attics, basements, or wall cavities before ever reaching your living areas. Prep work determines long-term success: Cleaning rust, dust, and grease off metal surfaces with a wire brush and rag is critical to achieving a permanent, airtight seal. Combine mesh with mastic for large gaps: For seams wider than one-sixteenth of an inch, embed fiberglass mesh tape into mastic paste to prevent…