Green Home Tips: Seal Leaks in Ductwork

Saving Energy

You can lose hundreds of dollars a year in utility bills if your air ducts aer not sealed properly. Sealing ducts can reduce your home's heating and cooling bills by an estimated 30% per year by allowing the cooled or heated air to go into the house where you want it.

Improving Health

Leaky air ducts can also affect your health by allowing dust, mold, humidity, radon gas, pesticides, and carbon monoxide to enter your home from basements, attics, garages, and crawl spaces.

Description & Characteristics

The duct system used in cooling and heating homes is made of a collection of tubes that distrubute cooled or heated air throughout your home.

The tubes are round or rectangular and are made of sheet metal, fiberglass, or other materials.

Leaks in your duct system may be caused by:

  • Ducts that are disconnected
  • Connections between ducts that are not properly sealed
  • Ducts that are sealed with poor quality materials
  • Small or big holes in ducts

Installation & Performance Improvement Tips

The first step in determining if your system has leaky ducts is to assess the comfort level of your home. Do you have high summer and winter utility bills as a result of your air conditioner and furnace running all the time? Do you have rooms that are difficult to heat and cool? Do you have stuffy rooms that never seem to feel comfortable? Are your ducts located in an attic, basement, garage, or crawl space?

Once you have determined that there is a comfort problem in your home, conduct a visual inspection of your ductwork. Some common locations to find leaks are where the ducts connect to vents, registers, and grills in walls, floors, and ceilings. Are there any ducts that are disconnected or loose? Are there ducts that are tangled or kinked? Are there any gaping holes?

Take the followng steps to repair leaky ducts:

  • Replace damaged ducts.
  • Straighten out tangled or kinked ducts.
  • Reconnect disconnected ducts and seal with mastic or metal tape. Do NOT use duct tape, as its adhesive dries out and does not provide a permanent seal.
  • Seall all vents, registers, and grills tightly to the ducts.
  • Relocate ducts from unconditioned spaces, such as attics and crawl spaces, to conditioned space. If that is not possible, then insulate ducts in unconditioned areas with duct insulation that has a 6 or higher R-value.

Product Types

The estimated cost of mastic or metal tape is $8-$15.

The estimated cost of sealing leaky ductwork in a home can range from $10-$30.

Mastic and metal tape may be purchased at hardware stores.

Originally published for the Global Green USA Build It Back Green Program.