The answer to 'how long will air duct sealing last' is that properly applied air duct sealing can last 10-20 years or more, depending on the materials used and the conditions in your home. Duct sealing helps prevent air leaks that can reduce the efficiency of your HVAC system, and the sealants used are designed to be durable and long-lasting.
Over time, the sealants may start to degrade due to temperature changes, humidity, or other factors. Regular inspection and maintenance of your ductwork can help ensure the sealing lasts as long as possible. If you notice any cracks, gaps, or other issues with your ductwork, it's best to have a professional HVAC technician take a look and make any necessary repairs or resealing.