When Metal Ducts Sweat: Stopping Mold, Mildew & Attic Air Infiltration

Watch as our Crew Leader tracks down and seals a leaky attic duct system that was doing more than wasting energy—it was causing sweating metal boots and mold‑friendly conditions in the ceiling sheetrock. In this Real Results project, we hit the rusty metal AC boots that were reaching dew point, dripping, soaking insulation and the drywall below. But more than just the dripping boots and duct connections, a major area for condensation to occur is under the metal supply plenum. Rarely air-sealed tightly, if at all, since it's out of sight, it's out of mind and into the insulation underneath. Fixing hidden plenum and duct leaks reduce moisture concerns that lead to mildew, mold, and indoor air quality issues. In this video, you’ll see: 🧊 Old duct boots and insulation wrap dripping, sweating, and leaking into the attic ✅ A Duct Blaster test that proves how much air the system was losing through duct leaks ✅ What a properly sealed ductwork system should look like at the seams, boots, and transitions for long‑term airtightness ✅ Final Duct Blaster test results showing leakage cut down to healthy, realistic numbers ☣️ Real before‑and‑after airflow and moisture‑control results that prove the leaks—and the sweating metal—were actually fixed Sealed, airtight ductwork helps control moisture, improve comfort, and lower energy bills when it’s tested and sealed correctly with mastic. If you’re seeing sweating ducts, rusty boots, mildew stains, or mold spots around your vents or in the attic, this video shows what a proper attic duct sealing job looks like and the kind of results you should expect when it’s done right. Learn more about fixing leaky ducts and crawlspaces: 📝 Why spray‑foamed crawlspace ductwork stops moisture damage and saves energy: https://diversifiede.com/2026/02/26/c... 📝 How utility rebate programs help pay for duct sealing and insulation upgrades in Louisiana: https://diversifiede.com/2025/04/25/e... 📝 Why leaky attic ducts turn your home into a vacuum (and drive up bills): https://diversifiede.com/2026/04/08/h... 📝 Our spray‑foam insulated ductwork services: https://diversifiede.com/insulation/s... 🌐 Duct testing and sealing for tighter, healthier homes: https://diversifiede.com/home-perform... 🌐 Website: https://diversifiede.com ☎️ If you're in the Greater New Orleans to Baton Rouge area and want more information and what programs are available that incentive these improvements, call 504‑273‑7779. Diversified Energy has been focused on energy‑efficient homes since 1999, delivering building‑science–based solutions across multiple climate zones and thousands of projects. Our team combines decades of field testing experience with services that include duct sealing, insulation upgrades, and support for utility incentive programs. Instead of quick fixes, we look at whole‑building performance—indoor air quality, comfort, energy savings, and long‑term sustainability—to make sure every job is done the right way for our clients.