4 HVAC Duct Types Used in Heating and Cooling

Channel your home’s energy with the right kind

Contemporary condominium with air ducts and ceiling fan
Photo: Carlina Teteris / Moment / Getty Images
Contemporary condominium with air ducts and ceiling fan
Photo: Carlina Teteris / Moment / Getty Images
Melissa Graham
Written by Melissa Graham
Contributing Writer
Updated Mar 7, 2025
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Ductwork is the hidden backbone of your home’s HVAC system. While you may not be familiar with all the HVAC duct types that are out there, it helps to know which variety is in your home or which type works best should you need a repair or complete replacement.

Type of DuctworkLifespan in Years
Flexible10–15
Sheet metal 30–50
Fiberboard10–20
Fiberglass lined15–25
Pro Tip

Quality ductwork will increase the efficiency of your HVAC, sometimes even by 20%-30%. This is so because there is reduced air leakage due to better insulation and more optimized airflow. Because this makes your HVAC work more efficiently, it really doesn't have to work too hard to keep the desired temperature; thus, its energy consumption is lowered directly.

Yashar Mosaferi

President of Klondike AC

1. Flexible

Flexible ductwork consists of a metal wire coil covered by a layer of plastic. Its thermal insulation is made of glass wool, which helps reduce heat loss or gain and improves energy efficiency. This type of ductwork is commonly used in smaller, single-story homes with tight spaces. 

Pros Cons
Budget-friendly Damages easily
Easy to install Prone to sagging
Good for small spaces Can restrict airflow over time

Best for: Smaller homes with tighter budgets

2. Sheet Metal

As its name suggests, sheet metal ductwork is made of galvanized steel, aluminum, or stainless steel. This type of ductwork can be shaped into round, spiral, or rectangular ducts and is one of the most durable types available. It falls on the higher end of the price range due to its ability to resist mold and pests. 

Pros Cons
Durable More expensive
Resistant to mold and pets Requires professional installation
Promotes good airflow Prone to air leaks

Best for: Larger homes in humid or extreme climates 

Read more

3. Fiberboard

This ductwork type consists of compressed resin-bonded fiberglass topped with a foil laminate to prevent moisture buildup and leakage. Because of its rough material, it can be prone to trapping dust and debris, so it helps to consider the cost of air duct cleaning if you’re thinking about installing fiberboard ductwork.

ProsCons
Built-in insulation Shorter lifespan
Budget-friendly Can trap dust and debris
Reduces noise Less airflow efficiency

Best for: Small homes in moderate climates 

4. Fiberglass Lined 

Fiberglass-lined ductwork is made of sheet metal ducts coated with a layer of fiberglass insulation. It’s beneficial for open spaces that need noise control and more consistent thermal control.

The main downside is that it’s possible for fiberglass-lined ducts to deteriorate and release small particles of fiberglass into the air, which can be harmful for people who struggle with breathing conditions like asthma.

Pros Cons
Improved insulationCan affect indoor air quality
Quiet Shorter lifespan
Controls condensation Difficult to clean

Best for: Commercial buildings or offices

Read more

Choosing the Right Ductwork

4 ductwork types compared visually, including metal sheet, flex, fiberglass, and fiberboard

Don’t try to climb up into an attic to learn more about duct systems. A local ductwork installer can take a look at your home or plans for your home to make recommendations on the right type of ductwork for you. HVAC ductwork can make the difference between a well-heated home or one that harbors mold and has you shivering in below-freezing temperatures.

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Learn more about our contributor
Melissa Graham
Written by Melissa Graham
Contributing Writer
Melissa has spent over ten years writing about home design, style, and DIYs for regional and national publications.
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