Duct Insulation and and Sealing Considerations

installing clean duct filter

One of the most important systems in your home, though it's hidden beneath your feet and over your head, may be wasting a lot of your energy dollars. Your home's duct system, a branching network of tubes in the walls, floors, and ceilings, carries the air from your home's furnace and central air conditioner to each room. Unfortunately, many duct systems are poorly or improperly insulated and sealed. Consider this article's tips before beginning any duct work yourself or calling a professional.


Ducts that leak heated air into unheated spaces can add hundreds of dollars a year to your heating and cooling bills. So, insulating ducts that are in unconditioned spaces is cost effective. If you are buying a new duct system, consider one that comes with insulation already installed. Also be sure that a well-sealed vapor barrier exists on the outside of the insulation on cooling ducts to prevent moisture buildup.

Basement Considerations

Remember that insulating ducts in the basement will make the basement colder. If both the ducts and the basement walls are uninsulated, consider insulating the basement walls as well as the ducts.


Sealing your ducts to prevent leaks is even more important if the ducts are located in an unconditioned area such as an attic or vented crawl space. If the supply ducts are leaking, heated or cooled air can be forced out of unsealed joints. In addition, unconditioned air can also be drawn into return ducts through unsealed joints.

During the summer, hot attic air can be drawn in, increasing the load on the air conditioner. In the winter, your furnace will have to work longer to keep your house comfortable. Either way, your energy losses cost you money.

DIY Minor Duct Repairs

Step 1 – Check for Air Leaks

Check your ducts for air leaks. First, look for sections that should be joined but have separated. Then, look for obvious holes.

Step 2 – Use the Appropriate Repair Tape

Never use duct tape to repair and seal your ducts. Instead, look for tape with the Underwriters Laboratories (UL) logo to avoid tape that degrades, cracks, and loses its bond with age. Seal any air leaks or sealing issues with this tape.

When to Call a Professional

Although minor duct repairs are easy to accomplish, ducts in unconditioned spaces should be sealed and insulated by qualified professionals using the appropriate sealing materials if there are larger issues.