DIY duct sealing is possible for accessible leaks using mastic sealant or HVAC foil tape, but knowing where and how to apply them is essential. While small gaps are easy to fix, hidden or large leaks can reduce airflow, waste energy, and require specialized equipment. Incorrect sealing may worsen system performance. Understanding your duct layout helps determine what you can handle safely. Tap here to learn when DIY duct sealing works—and when to call a pro.
