4 Types of Ductwork and How to Choose One

Ducts are all about getting air where it needs to go—especially air being pumped out of your furnace or HVAC system. But what are ducts made of—and what are the types of ductwork available? We’re glad you asked! Read on to learn about different types of ductwork and how to determine which is best for your home with the help of a professional duct installer.

1. Flexible Ducts

Flexible air ducts are lightweight and ideal for tight spaces. This type of ductwork is less expensive and easier to install than rigid ductwork. However, their accordion-like structure can lead to airflow issues, collapses, or kinks.

Flexible HVAC ducts are composed of a metal wire coil surrounded by a flexible metal sheath. They are made from materials like PVC or polyethylene and they offer versatility and easy installation in residential and commercial HVAC systems. A major benefit of this type of ductwork is they are lightweight, making them easy to handle and maneuver, especially in tight spaces or complex ductwork configurations. They’re also resistant to corrosion.

While plastic flexible ducts offer many benefits, they may have limitations in high-temperature environments. Additionally, they often aren’t as durable as metal ducts. Still, their affordability and flexibility make them a popular choice for HVAC installations.

Best for: Homes with tight spaces or complex ductwork layouts.

2. Sheet Metal Ducts

Sheet metal ductwork is the most common type because it's tough and long-lasting. Plus, it has a smooth surface for easy cleaning. The cost of replacing sheet metal ductwork ranges from $7 to $13 per linear foot.

Rust-resistant sheet metal ducts can be round or rectangular, and while they may be more expensive to install than flexible ducts, they’re more sustainable. Sheet metal ducts are considered the most energy-efficient material because of their exceptional durability and enhanced airflow. However, they can also leak air at the duct joints and seams. 

Galvanized steel is a great duct material because it is durable and non-porous. These qualities can help keep your HVAC system healthy and mold-free. 

Rigid ducts can also be made of aluminum, which has similar benefits but is more lightweight. Like galvanized steel, it is non-porous, so it naturally inhibits mold and bacteria growth for improved air quality. Due to its lighter weight, aluminum ducts are easier to install, making it the preferred material for sheet metal ducts.

Best for: Moisture-prone areas and homeowners wanting sustainability.

3. Fiberglass

Fiberglass-lined air ducts, often found in commercial buildings, feature a fiberglass coating for insulation and sound muffling. However, this type of ductwork poses risks of releasing fiberglass particles into the air and can harbor mold and bacteria due to their porous surfaces. Other materials with fiberglass, such as fiberglass-reinforced plastic (FRP), are used in duct construction. FRP is durable, lightweight, corrosion resistant, and can handle high air pressure.

Best for: Commercial buildings.

4. Fiberboard

Fiberboard ductwork features strands of fiberglass bonded with a resin and then laminated by a metal foil exterior, which acts as a barrier to moisture and helps prevent fiberglass particles from escaping. These ducts are less expensive than sheet metal alternatives but may foster mold and mildew growth, particularly in humid climates. Regular maintenance and monitoring are essential to prevent mold growth and ensure optimal performance.

Best for: Budget-conscious homeowners in dry climates.

Factors to Consider When Choosing Ductwork

Every home and HVAC setup is different, so there isn’t a one-size-fits-all answer to the question of which type of ductwork to choose. It’s all about your individual and home needs.

For example, if your home has the space for them and it’s in your budget, rigid ducts made of galvanized steel or aluminum is a more durable option with the bonus of keeping your air quality clean. On the other hand, if your home is smaller or was not designed with ducts in mind, flexible ducts may make it possible to install your HVAC system without needing to do a more serious retrofitting or remodeling job. 

Keep in mind that your HVAC system may also have specifications and requirements for air pressure, temperature, and other factors that could affect which type of ducting will work best. If you have questions or you’re ready to get started, contact your local duct installer—they’ll be happy to help! These pros can determine the best type of ducts for your home and make an installation plan for you.