The answer to 'how long does air duct sealing last' is that properly installed air duct sealing can last 10-15 years or more. Duct sealing is a process of using mastic or metal tape to seal any gaps, cracks, or joints in your home's ductwork to prevent air leaks. When done correctly, this sealing can significantly improve your HVAC system's efficiency and last for over a decade.
The longevity of duct sealing depends on several factors, including the quality of the materials used, the thoroughness of the installation, and the condition of the ductwork. Properly sealed ducts that are protected from damage and regular maintenance can maintain their effectiveness for many years. However, over time, the sealing can degrade due to temperature changes, vibration, or other factors, so it's important to have your ducts inspected periodically by a professional HVAC technician.