Flexible HVAC duct failures:

Beginning here with an example from ATCO™ Rubber Products, we list and describe severe deterioration in the plastic exterior and sometimes plastic interior of flexible HVAC ductwork used in heating and air conditioning systems throughout North America.

We include product names, identification photographs, and suggestions for the detection & repair of leaky, damaged flexible ductwork.

ATCO gray flex duct HVAC ductwork deterioration: this article discusses ATCO™ Rubber Products brand gray flex duct disintegration failures with references to product failures by manufacturers of similar flexible duct work products.

We provide flex duct identification & defect recognition photographs illustrating heat-damaged flex-duct covering materials and we explain the implications on home energy costs when this material is installed in buildings.

Gray Flex-Duct Failures in HVAC Systems: severe deterioration found

ATCO Rubber Products gray flex-duct deterioration in hot spaces

This article describes ATCO™ brand gray flex duct failures that appear as loss of the gray plastic duct covering due to brittleness that appears to be caused by exposure to heat (such as in a hot attic), with references to product failures by several manufacturers of flexible duct work, including Alloy Systems™, ATCO™ Rubber Products, Goodman™ flex duct, Owens Corning™ flex duct, Owl™ flex duct.

[Click to enlarge any image]

We believe that none of these defective flex duct products is currently sold but both may be found in older homes. Note: not all Owens Corning flex duct products share this defect and disintegration problem.

Thanks to Nate Stitzlein for these photos of ATCO Rubber Products gray flex duct disintegrating in an attic.

As Nate reported,

I inspected a 1989 condo this afternoon and found this duct work in the attic.

Thought you might be interested in the images and the name of the company on the duct work." Mr. Stitzlein is a professional home inspector with Crow Home Inspection, llc in central Ohio and can be contacted at www.crowhome.com

The loss of the protective plastic covering on flex duct poses several concerns including loss of the duct insulation, increased air conditioning system operating costs, and possibly air leaks out (if supply ducts are damaged) or un-wanted attic debris leaks in (if return ducts are damaged), and in-duct condensation in the HVAC system leading to mold and indoor air quality concerns.

These gray ATCO flexduct images have the visual characteristics of thermally-degraded "gray flexduct" failures.

I suspect but don't know, that the reason that we see this failure across multiple flexduct brands may be that everybody bought the same gray plastic duct exterior wrap from a single manufacturer, simply having their own brand and text imprinted on it.

Often there are such common sources across multiple product brands that are not widely known.

This ATCO gray flex duct or "flex duct" air conditioning duct work material is a defective product. In hot attic spaces or where exposed to UV light, the plastic of this flexible air conditioning duct material disintegrates leaving its fiberglass insulation exposed to also disintegrate, leak, or possibly blow into the building living space.

Replacement of the duct work is required - a significant expense, more so where damaged ductwork has been run in side of enclosed building cavities such as ceilings & walls. Where this duct is found in a building it should be replaced. When a heating or air conditioning flex-duct product has lost its exterior plastic covering the effects are these:

1. The cost of heating or cooling the building is increased due to lost insulation: 
   
   because the ducts are no longer insulated from the ambient temperature in the attic or crawl space where they are located. For example, an air conditioning duct passing through a hot attic and missing its insulation will be heated by the ambient attic air, delivering warmer air to the living space than is desired.
2. The cost of heating or cooling the building is increased due to leaks:
   
    because damaged ducts are more likely to leak, cooled or warmed air intended for the occupied space may be lost in the attic or crawl space where the damaged HVAC ducts are located.
   
   In addition we might see these two indirect problems developing:
3. Increased circulation of fiberglass particles
   
   from the duct insulation or from building insulation which may be picked up and blown into the building air supply
4. Mold growth
   
   in the HVAC ducts due to loss of insulation and increased in-duct condensation in some circumstances.
   
   See Flexduct Lawsuit at our references below.

Below at Technical Reviewers & References we include Flexible Air Duct Installation Manuals, standards, guidelines, and contact information for several flexible air duct manufacturers as well as access to Flexible Duct Performance & Installation Standards provided by the Air Diffusion Council.

Other Gray Flex-Duct Products Surviving Attic Heat

CertainTeed Certaflex-G25 Flexible HVAC Duct : Attic Inspection

An example of gray flex duct that is surviving the heat in hot attic spaces includes these CertainTeed Certaflex-G25 Class-1 Air Duct material. Eric Van De Ven, our flex duct detective in the field, contributed these photographs. Mr. Van De Ven explained

It appears this duct work is thicker than the others and wasn't deteriorated. It was installed in 1986 and this attic was at least 130 degrees today.

You will notice in our second photo below) that while the flex duct in this home was not obviously heat-deteriorated, it had been cut or mechanically damaged. We recommend patching minor tears with a plastic or foil duct tape.

Certainteed makes a wide range of building insulation products including the flex-duct above and

also FIBERGLASS DUCT, RIGID CONSTRUCTION.

List of plastic-covered flexible HVAC duct products that appear to deteriorate in hot spaces like attics

Readers concerned with deteriorating plastic and fiberglass-covered flex duct in buildings should see the several HVAC duct failure reports listed below at CONTINUE READING .

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Can I just replace the damaged exterior covering of disintegrated flex duct?

How can the disintegrated flex duct skin be replaced? New duct is overkill and costs a lot. A slide over skin or tape secured skin would make sense. On 2026-09-20 by Robert

Answer by InspectApedia Publisher (mod) - opinion about re-covering versus replacing damaged HVAC Flex Duct

@Robert,

Thank you for an interesting question about the economics of repairing disintegrating HVAC flex duct.

My opinion is that it would probably be more cost effective to replace the damaged flex-duct than to try to repair it by installing a new exterior cover.

Here's my reasoning:

1. When we encounter disintegrating gray plastic covered flex duct in buildings not only has the flex duct covering begun to fall apart, the insulating cover is also damaged and often missing in sections. So just re-covering the duct won't restore the needed insulation. Leaving the insulation off would increase heating or cooling costs.

2. Watch out: Worse, often it's not just the exterior plastic cover that's disintegrating, it's also the liner on the inside of the flex duct as well. At FIBERGLASS HAZARDS we warn that many people suffer respiratory irritation and skin irritation when exposed to high levels of airborne fiberglass, a condition that would be more serious if the fiberglass is exposed inside the HVAC system's ductwork where it can be blown into the occupied space.

3. My OPINION is that even if there were no labor or installation cost to try to slip a plastic "sock" over damaged flex duct (that is, if you decide to handle the job yourself) or to wrap a spiral cover of plastic or foil repair tape around the ductwork, the cost just of the repair material may be higher than you'd think.

100 feet of 6-inch foil insulated flex duct like the example I'll show here from HVAC Premium hvacpremium.com is about $245 for 100 feet of ductwork - probably more than enough to replace typical residential flex duct in an attic.

I searched and did not find any suitable plastic slip-over tubing that one might use as a "repair sock" over damaged flex duct but I did find many examples of repair tape products used for repairing damaged insulation covering, such as the foil or white vapor barrier tape I'll show in a subsequent post there.

To cover 100 ft. of 6-inch diameter flex duct you'd need 22,676 square inches of wrapping. To wrap this with 6-inch wide foil repair tape you'd need a bit more than two rolls of 6-inch x 250 ft. long tape - costing $70. - so you're right that the covering, if you could do the job with sufficient neatness - would be less than buying new ductwork, but you'd only be able to cover the exterior - leaving the disintegrating duct interior un-treated.

Similarly, if we just tried wrapping the duct with polyethylene sheet cut from a roll of that material (the cost of a 100 ft. roll is about $90.) that too leaves the duct interior un-treated.

4. For a homeowner who's going to hire a repair contractor, I suspect they'd have trouble finding a contractor willing to wrap rather than repalce the ductwork as the labor cost would be many times greater to wrap than to disconnect, bag, and remove the old ductwork and simply install new ducting.

Bottom line: while I, too, am often tempted to find a low-cost Do-it-yourself repair to put the "experts" and "professionals" to shame, very often I've found that doing the job right, with the right materials, the first time is actually less costly and much less trouble. And in this case I'm worried too about leaving a fiberglass hazard in place where the duct interior covering also is falling apart.

I'll appreciate hearing your further thoughts on this and to hear if you know of an easy, inexpensive repair method.


Here's an example of the repair tape I mentioned.

More on the question of repairing rather than replacing damaged flex duct:

Here's an example of 6 mil poly sheeting that you could use to try to wrap damaged exterior of plastic flex duct but again

Watch out: I warn that you're leaving the risk of airborne fiberglass contamination from the duct interior. $90. plus a bit more for a few rolls of duct tape or similar tape to secure the plastic inplace.

Daniel F

All that arm-waving said, if you want to try a DIY flexduct re-covering project, and if you confirm that the interior of your flex duct is both un-damaged and not getting brittle or fragile, then I'd use 6 mil poly sheeting and duct tape.

Post a photo of your flex duct to let me take a look.

Daniel

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Continue reading at DUCT ROUTING & SUPPORT or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

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• FLEX DUCT SOURCES & HISTORY
• GRAY FLEXDUCT FAILURES - home
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  • ALLOY SYSTEMS FLEXDUCT
  • GOODMAN GRAY FLEXDUCT
  • OWENS CORNING FLEXDUCT
  • OWL FLEXDUCT
• LEAKY DUCT CONNECTIONS

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