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Rigid Metal vs AlumaFlex Ductwork. Which is best for my southern california home?

By Your Comfort Advisor 11/8/16 9:23 AM Time to read:

Looking to upgrade your Southern California homes HVAC system? There is more to consider than which AC unit or furnace to buy; you’ll have to consider upgrading your ductwork as well. Forced air heating and air conditioning split systems and packaged units are the most popular equipment installations in North America, and both require a reliable network of ducts in your home.

Once you set the thermostat to your desired temperature, air is pulled from the home environment, through the return ducts and air filter, and into your system to be heated or cooled. The treated air is then returned to the home via the supply ducts. The condition of your ductwork and its designed layout can have a significant effect on the comfort of your home. Some things your Comfort Advisor will consider when designing your duct system are as follows:

  • air flow
  • location
  • environment

Once you know how these things affect your ductwork, you can understand how your Advisor makes educated decisions on when to use rigid or flexible ducts.


This type of duct consists of a flexible sheet of plastic reinforced by spiral metal wire ribbing, fiber insulation, and a tough mylar outer sleeve. Because of the materials it is made of, the length of tubing bends easily. The insulation comes in different thicknesses or “values” labeled as R4, R6, and R8. The Building Energy Codes Program (a division of the Department of Energy) requires that the insulation covering residential ductwork be a minimum of an R6 value and that of commercial duct be a minimum of R8. At Burgeson’s we use R8 for residential as well as commercial applications. Many installations that occur in homes built after 1960 will have this type of duct.

Air flow: This is determined by the dimension of the duct used as well as the positioning of internal dampers. Various dimensions are used to force air into specific sections of the home. If the wrong dimension of duct used, it can affect the noise level, efficiency level and work load of the equipment.  

Location: Tight spots and tricky attics require FlexDuct capability. Installers have the capability to follow a home’s angles and work around its obstacles.

Environment: Flexible duct with a value of R8 can withstand greater temperature swings and protect the temperature of the conditioned air inside the duct.

Rigid ductwork

This type of ductwork is made from a thin sheet metal, typically sealed and encased in insulation with a value of R4, R6 or R8. This type of duct is best used in homes with basements instead of attics and when exposed or rooftop duct is required.

Air flow: The air-facing side of the duct is made of smooth material, giving the tube very efficient air flow. The joints of the ductwork are usually sealed and taped, all but eliminating leaks.

Location: Ducts made of sheet metal do best in basements or rooftops as they are more durable and resistant to collapse or pests.

Environment: Rigid sheet metal duct stands up to outdoor weather. When incorporating exposed duct as a design feature, rigid duct is the only way to go.

If you have any question about what ductwork would be the best support for your equipment, ask one of our Southern California HVAC professional. The Comfort Advisors at Burgeson’s are available to answer your questions by phone or email.