Flexible vs. Metal Ductwork: Which Should You Choose?

February 10, 2021 6:08 pm Published by Leave your thoughts

The saying “out of sight, out of mind” couldn’t be truer when it comes to a building’s ductwork system. It’s easy to forget about air ducts when they’re hidden behind walls and in the basement. However, homeowners and business owners in St. George, UT must familiarize themselves with the difference between flexible and metal ductwork so they know which is best for their property.


A key difference between flexible and metal ductwork is that flex duct is notoriously easier to install. It’s lightweight and can bend however is necessary in order to adapt to the heating or cooling system. Installation goes much faster, reducing the cost of labor and downtime for your business.

In comparison, metal ductwork has a meticulous installation process. Sheet metal requires precise measurements so that it fits into the building’s dimensions. The rigid material is also more difficult to carry and place in the right position. As a result, metal ductwork installation is a lot pricier.

HVAC design

Flexible ducts are best suited for branching off the main plenum of your HVAC system. They run throughout the building and carry air to individual ceiling vents. Flex ducts are available in a variety of materials that conform to the building’s shape as necessary, like rubber, stainless steel, silicone and polyurethane.

In fact, material is one of the main differences between flexible and metal ductwork. Metal ducts are constructed with rigid sheet metal, making them suitable for the main pillar of a trunk-and-branch ductwork layout. They’re directly connected to furnaces and supply air to the various flexible branches.

Air resistance

One downside to flexible ductwork is that the material creates more resistance to air flow. Unlike metal ducts, flexible ones often crumple in ways that make it more difficult for supply air to reach its designated ceiling vent. Less experienced contractors will arrange flexible ducts into awkward configurations with sharp turns and sections that sag under their own weight.

While metal ducts are more expensive, they’re well worth the cost. Sheet metal retains its shape and has low air resistance. Businesses in St. George, UT can enjoy reduced energy bills with metal ductwork because the furnace and AC unit won’t have to work as hard to supply air throughout the building.


Flexible ductwork not only resists airflow, but is also more susceptible to a poor installation. Any number of factors can go wrong, including a poorly sealed joint, excessive length that lacks support and crumpled sections. Also, the material itself is less durable than sheet metal. Systems with flex ducts require more frequent maintenance from an HVAC expert in St. George, UT.

Durability is the number one reason why metal ducts make a better long-term investment. Though expensive, metal ductwork requires very little maintenance and withstands extreme outdoor temperatures. For this reason, sheet metal is the best material for lowering energy costs.

No matter the kind of ductwork in your building, the HVAC system needs regular maintenance in order to perform at its best. If you don’t remember the last time someone assessed your building’s ductwork, schedule an inspection with the HVAC contractors at Calaway Heating & Air Conditioning. Spending a little on maintenance will save you big time on costly repairs down the road.

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