3 Types of Duct Insulation and Pros and Cons of Each

Maintaining a cozy home is all in the details

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Duct insulation, often hidden from view within the depths of your home, plays a pivotal role in regulating indoor temperatures, energy efficiency, and environmental comfort. If you're preparing a project, you'll need to know which types of duct insulation to choose from. Whether seeking optimal thermal control, soundproofing, or cost-effective solutions, understanding the options is your first step toward achieving indoor comfort and efficiency.

1. Fiberglass

Air duct covered with fiberglass insulation
Photo: Tobias Titz / fStop / Getty Images

Fiberglass duct insulation is a versatile and widely utilized option for insulating residential and commercial ductwork. Made up of delicate glass fibers, this insulation is praised for its affordability and efficiency in conserving energy. The material is flexible for both round and rectangular ducts and comes in various thicknesses and R-values—more on that later.

This insulation material can be purchased fully wrapped in aluminum or perforated foil, offering superior sound absorption.

ProsCons
Low-cost and DIY-friendlyRisk of respiratory and skin irritation
Prevents condensationCan release airborne particles during installation
Good temperature controlLoses insulation properties over time
Fire-resistantNot good at soundproofing

Best for: Budget-conscious homeowners and DIY enthusiasts.

2. Polyethylene

Roll of polyethylene foam insulation
Photo: Sergey Pakulin / iStock / Getty Images Plus / Getty Images

Polyethylene (PE) duct insulation is commonly used to minimize heat loss or gain within the ductwork. It is made from polyethylene foam, a lightweight, flexible, and resilient material applied to the interior or exterior of ductwork. This material could also be a good choice when installing dryer vent insulation that connects to the home's exterior. Of course, this extra ruggedness comes with a slightly higher price tag, making polyethylene a more expensive alternative to fiberglass.

ProsCons
Minimizes heat transferExpensive
Flexible materialNot fire-resistant
Resistant to moisture and condensationNot DIY-friendly

Best for: Higher-budget projects and homeowners looking to reduce the risk of mold growth or corrosion within ducts.

3. Mineral Wool

Air duct covered with mineral wool insulation
Photo: MyrKu / iStock / Getty Images Plus / Getty Images

Mineral wool duct insulation, or stone wool or slag wool insulation, is a high-performance thermal insulation material that can be installed with a sheet metal liner. It’s manufactured from molten rock or industrial slag, spun into fibers, and bound together to form rigid or semi-rigid boards, blankets, or batts. This robust insulation material is known for its exceptional resistance to heat and fire and its ability to provide both thermal and acoustic insulation. 

Many people also like that mineral wool is made from environmentally friendly recycled materials. For this reason, mineral wool is considered a top choice when creating an eco-friendly home.

ProsCons
Excellent thermal resistanceExpensive
Fire-resistantRigid and challenging to install
Good soundproofingNot good for tight spaces
Resistant to moistureHas a heavy weight
Durable and long-lastingCan cause respiratory or skin irritation while handling

Best for: Homeowners looking to maintain consistent indoor temperatures and improve energy efficiency.

How to Choose Insulation for Ductwork

When shopping for duct insulation, the R-value is arguably the most crucial factor to consider. It measures the thermal resistance of an insulation material, indicating its effectiveness in preventing heat transfer. A higher R-value means better insulation properties, which is particularly important for ducts, as they control the flow of conditioned air throughout your home.

To make an informed choice, first assess your location's climate. Regions with extreme temperatures require insulation with higher R-values.

 Illustrated R-Value zone map of the United States, depicting zones 1 through 8 in color
Photo: Lara2017 / iStock / Getty Images Plus / Getty Images

Each region corresponds with a specific R-Value:

R-Value insulation table showing general R-Value recommendations based on climate zones 1 through 8

Additionally, consider the location of your ducts, whether they are in unconditioned spaces or near external walls, as this affects the necessary level of insulation. Be mindful of local building codes and regulations, which may dictate minimum R-value requirements for your area.

When selecting the most suitable type of duct insulation for your specific needs, budget is another important consideration. Fiberglass is the least expensive choice, but mineral wool's durability may make it more cost-effective over time. As you're considering the cost, remember you need to clean your ducts. Air duct cleaning costs can range between $270 and $500, depending on the size and type of ductwork and insulation you have.

Evaluate the duct system's location and conditions. Polyethylene's moisture resistance makes it ideal for humid environments, while mineral wool provides thermal and acoustic insulation. If fire safety and soundproofing are paramount, mineral wool stands out.

Insulating Duct Work Yourself vs. Hiring a Pro

If you plan to do a DIY installation, consider which one best suits your skill level. Fiberglass is relatively straightforward for DIY projects, whereas polyethylene and mineral wool may require professional expertise due to their unique materials and characteristics. Fiberglass is the way to go if you're looking for an option that offers creative ways to hide ductwork. Ultimately, your decision should align with your specific project requirements and priorities, which may vary. Contact a local duct installer for advice if you have any concerns. 

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