Best Practices of Ductwork Design

Best Practices of Ductwork DesignIf you are designing a new home or retrofitting areas in your current home, you certainly want and expect your contractors to use best practices of building science. The same is true for your ductwork system. Though, that wasn’t always the case when it came to construction. Read on to learn what you need to know about the tubes that carry the cooled and heated airflow that keep you comfortable.

Metal, Fiberglass, or Plastic?

Ducts are traditionally fabricated from thin sheet metal. In recent years and decades, flex ducts and plastic are often used. Many older homes use cavities inside walls, floors, and the ceiling as airways. Make sure all of your air ducts are installed using actual industry-approved materials.

Location and Insulation

The fewer turns and splits your conditioned air must travel through, the more efficient your ductwork system will be. This translates into lower energy bills and greater comfort. Ducts should take the shortest route possible from the air handler to the outlet. Conditioned areas, such as raised floors and chases, are preferable. Ducts located in unconditioned spaces should be insulated.

Sealing Materials

Cloth “duct” tape, as it’s called, should never be used to seal ductwork. It will peel and fall away very quickly. Your HVAC contractor should only use industry-approved sealing materials, such as metal tape, mastic sealant, clasps, and aerosol sealant.

Sizing Ductwork

If your contractor is sizing your duct system (or heating and cooling systems) based on the square footage of your home, find a different contractor. There are dozens of variables that affect heat gain/loss on all sides of your home. Your ducts should be sized using software based on Manual D principles outlined by the Air Conditioning Contractors of America.

Balancing and Testing

Once your ducts have been installed, sealed, and insulated, they should be tested for balance and tightness. Any leaks should be resolved and airflow to each outlet and through your home should be in balance.

For more information about ductwork best practices for your San Diego area home, please contact Sherlock Heating & Air Conditioning today!

Our goal is to help educate our customers in the greater San Diego and San Marcos, California area about energy and home comfort issues (specific to HVAC systems).

Credit/Copyright Attribution: “iQoncept/Shutterstock”


  • Good to know about using duct tape. I thought that’s pretty much what duct tape was for, was to seal duct work. I had also never heard of metal tape before. Thanks for the heads up.

  • This was very educational. I didn’t know that ductwork is more efficient when there are fewer turns and splits. That seems like something that would be easy to overlook.

    • Thanks for taking the time to read!

  • My husband and I are currently designing a new home, so I appreciate your tips about finding a contractor with good ductwork practices. It sounds like the sealing materials play an important part when it comes to ductwork. I especially like how you point out that the location can translate into and more efficient system and a lower energy bill!

    • Thanks for your feedback!


Write a comment