Grey HVAC ducting

[Richard Overton]

Back in the late 80's there was a flexible hvac duct with a grey plastic jacket on it. I have noticed that the grey jacket degrades and falls away from the duct when even exposed to low intermittent light in an attic. The inner insulation and web wrap is intact along with the inside clear plastic liner. Any guidelines on how to call this out? Will the degradation continue to the point where you will have air leakage? Is there a standard being followed by the industry as to when to replace it?

Thanks for the help

[Bruce Ramsey]

The grey outer cover is a vapor barrier.  Once the plastic vapor cracks, splits and fails, the duct is no longer functioning as intended.  It is a defect.  It is past its useful life expectancy.  It is an ex-parrot.

I flag it as a defect and a repair item.  Keep in mind that the R-value is probably half of a new flexduct of the same size.  Replacement of the failed duct with new higher R-value duct and properly sealed joints will likley pay for itself in a year or two reduced utility bills.  The local gas and power companies are currently offering a $125 rebate each for having your ducts sealed.  Cost me $250 and I got $250 back from the utilities.  Free upgrade.  Lower utilities.

[Richard Overton]

Thanks, great call. I did not even think about it being a vapor barrier, but that makes perfect sense. i could see that the loss of the jacket could present a big condensation problem.

[Charley Bottger]

The plastic wrap on flex ducts deteriates due to improperly ventilated attics it does not with stand the heat 140 dgree attics. It also is used to hold the inner insulation in place. I have observed many attic ducts with just the inner plastic wire inserted plastic bare. I always call it out time to replace it.