When constructing or remodeling any ventilated building, one of the first decisions to make is what type of ductwork to use. While your architect or contractor will make some decisions due to physical limitations or environmental concerns, the building’s owner will have some latitude in deciding the best fit for the building itself. There are two categories of ductwork to choose from: rigid and flexible, and various subcategories within the rigid family.  However, in most applications, flexible is the choice in situations where rigid ductwork simply cannot be used, such as curved or other complex spaces. Regardless, the majority of your building will feature rigid ductwork. More on that below:


Sheet Metal

Sheet metal is the most common type of ductwork, the one in which we are accustomed to seeing our favorite spy character sneaking around. This ductwork class is the most durable and commonly used in situations where it may need to support weight or have people walking on it, such as beneath a floorboard. Additionally, sheet metal is very smooth and relatively easy to clean, making it a reliable choice if you are conscientious about the building’s amount of dust. Regular cleanings of your ductwork is a great way to mitigate dust particles, and sheet metal makes this job incredibly easy. Due to the smooth, non-porous sheet metal surface, there is little potential for the formation of mold and other biological agents. While sheet metal is an excellent choice due to these features and its simplicity to install, it can sometimes leak at its joints and seals.

Fiberglass Lined

Fiberglass-lined ductwork is essentially a modified version of its sheet metal counterpart, lined with fiberglass on the interior or exterior. This lining helps prevent heat loss and the formation of condensation, which makes it great for places that may experience low temperatures. Fiberglass lining shines when it comes to its ability to silence the hums of most HVAC systems. The fiberglass acts as an insulator, making this style a go-to for office buildings.

However, due to fiberglass’s porous and rigid nature, this ductwork style is more prone to those biological hazards one does not want in their air supply. Additionally, they are also susceptible to releasing tiny particles of fiberglass into the air. Due to these risks, well-trained professionals should regularly clean these ducts.


Fiberboard is compressed fiberglass laminated with a foil sheet. This lamination is excellent at protecting the ducts from moisture while also serving as an effective insulator. Fiberboard ducts are also the cheapest to install. However, these ducts are lined with fiberglass and therefore can harbor mold and other bacterial substances. Fiberboard is also known to restrict airflow due to the rigid nature of the fiberglass interior.


Flexible ductwork consists of a circular coil that covers a flexible material, such as plastic. Some of these also include an additional layer of insulation if needed. This style is by far the easiest to install and is relatively cheap. As stated before, flexible ductwork’s use is for awkward spaces for the installation of rigid material. Flexible ductwork is also the most likely to have leaks, as it can be easily punctured or damaged. They can also have kinks or bends that may restrict airflow and add stress to your HVAC system.

Determining which style of ductwork to use in your home can be a difficult decision. But with the help of a trained expert such as RG Mechanical, it can be made easy. Next time you are remodeling or beginning a new build, consider your ductwork options; call us at (812) 683-0675 to schedule an estimate for not only ductwork options, but install, and maintenance too.