What Materials Are HVAC Ducts Made From?

An HVAC system is set up to deliver air throughout a home to cool it off.

Flex Duct

Duct work comes in several types of material.
The air is moved through the house by an enclosed system called ducts. These ducts are made from a few different materials and the kind used for a particular system depends on spacing available for installation. .

Flex duct work is used in many cases for HVAC installations. The tubing, as its name indicates, is flexible, which allows it to bend and weave between wood beams and other obstacles in a crawl space or attic area. The tubing of flex duct work is plastic with a layer of insulation wrapped around it. The entire tubing is then sealed inside a vinyl vapor wrap to keep out moisture.

Metal Ducts

Metal ducts are constructed from sheet metal and are not flexible in any way. They are built in a rectangle shape and attached together with sheet metal screws. In some cases they are also wrapped in insulation to improve efficiency. Although as a whole this duct will stay together well, it is more likely to leak due to its many connection points. Metal ducts are normally made from steel or aluminum, but sometimes they come in copper if the ducts are going to be exposed to salty air.

Duct Board

Duct board is made of fiberglass. It is a lightweight installation, but fairly expensive. The board itself can be damaged easily by a careless worker, but once in place it lasts a long time. Leaks are less likely than with sheet metal, but still more likely than with flex duct.

Asbestos Duct

In times past, you might have seen ducts made with asbestos. This has since been proven to be hazardous and is no longer used. If you have an older home, it might be a good idea to have this checked out to ensure your family's safety.

About the Author

Keith Dooley has a degree in outdoor education and sports management. He has worked as an assistant athletic director, head coach and assistant coach in various sports including football, softball and golf. Dooley has worked for various websites in the past, contributing instructional articles on a wide variety of topics.