Ductwork Insulation – Choosing the Right Product for the Job


Insulating ductwork is vital to ensuring that air traveling within the duct system remains at the desired temperature for thermal performance – minimizing heat loss and gain – while preventing air leakage and condensation build-up.

Because ducts are made of lightweight material like sheet metal, they typically have poor thermal efficiency – losing energy due to conduction of heat from the warm surface and air leakage via small cracks and seams. In fact, typical duct systems lose 25 to 40 percent of the heating or cooling energy put out by the central furnace, heat pump, or air conditioner. As a result, a lack of proper duct insulation can translate to hundreds of extra dollars in heating or cooling costs, as HVAC systems are forced to work harder to maintain optimal temperatures.  

Moreover, uninsulated ductwork also exhibits poor sound dampening and acoustic performance. Controlling noise originating from air flow, crosstalk, and/or mechanical noise such as rattling is particularly crucial to multifamily dwellings and commercial structures. Noise reduction coefficient value (NRC) is the method used to calculate the level or value of how insulation absorbs multiple types of sound frequencies. Based upon the application and geographical region, NRC, along with thermal efficiency standards, may be incorporated into code requirements.

With so many variables to consider, it can be challenging to know which type of duct insulation is best suited for the job at hand. Fortunately, CertainTeed provides the three most common types of duct insulation used, all of which are GREENGUARD Gold Certified and meet code requirements.

Duct Wrap

Duct wrap is an excellent option for residential or commercial applications, particularly in commercial spaces like warehouses where thermal insulation is a priority but noise reduction is not. When properly installed (wrapped) around ducts, the wrap virtually eliminates the potential for air leakage and condensation issues on cold duct surfaces.

InsulPure™ Duct Wrap and WideWrap is designed to regulate unwanted heat loss.

Composed of uniformly textured, inorganic fibrous glass made with a formaldehyde-free binding agent, CertainTeed InsulPure™ offers health benefits to both installers and building occupants. This type of wrap is suitable for use with most heating, ventilating, and air-conditioning ductwork. Both InsulPure Duct Wrap and InsulPure Wide Wrap with FSK facing can be used in applications up to 250 degrees Fahrenheit. And InsulPure Duct Wrap and InsulPure Wide Wrap Unfaced can be used in applications up to 450 degrees Fahrenheit.

Duct Liner

Engineers will generally specify duct liner for multifamily and commercial projects that mandate noise reduction. The liner, which is fabricated into the duct offsite, functions to reduce airflow noise and crosstalk sounds while also meeting thermal efficiency requirements.

Our ToughGard® R Duct Liner offers excellent thermal and acoustical performance.

Designed with rotary-type glass fibers, CertainTeed ToughGard® R Duct Liner traps airflow noise, which is then dissipated by the glass fiber matrix. ToughGard has a strong surface that provides superior resistance against tears and punctures that can occur during fabrication, installation, and maintenance. The fiberglass liner will not deteriorate or corrode sheet metal ducts, and pests do not associate the fiberglass with food. Additionally, an EPA-registered antimicrobial agent in the insulation’s air stream surface reduces the potential for microbial growth.

Duct Board

Duct board is technical insulation that is often specified for industrial applications. Duct boards are made of semi-rigid fiberglass and can be fabricated using a machine like the Glass Master SG-220. This type of insulation tends to be inherently less noisy than sheet metal ductwork, as there is no metal-to-metal contact. It also provides significant thermal efficiency.

CertainTeed Ultra*Duct™ Black Duct Board features a built-in vapor retarder paired with a non-woven mat bonded to the air stream surface – helping to minimize condensation and the chance of material and system damage resulting from unwanted moisture. The durable, lightweight board can be fabricated into square, rectangular, or multisided sections, and can easily be cut and taped together to accommodate a variety of shapes.

Ultra*Duct™ Black Duct Board works for residential and commercial heating, ventilating, and air conditioning systems.

The Choice

Ductwork insulation is an essential factor in ensuring a building’s health, performance, and comfort levels. When specifying duct insulation, it is important to consider building type, code requirements, regional weather patterns, and project specifics. Fortunately, a variety of high-quality options are available to achieve a comfortable, quiet, and efficient conditioned space.

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