View Full Version : Metal ducts

Jeff Eastman
04-06-2007, 06:50 PM

Jim Luttrall
04-06-2007, 07:01 PM
Yes, the insulation is always installed after the metal during assembly.
That looks like the ducts have been damaged also though.

Jerry Peck
04-06-2007, 07:07 PM
"1 - can the insulation jacket on metal air ducts be replaced/repaired?"

Not effectively.

Besides, see that no-longer-round-duct? That's a sure sign the seam has opened up. That metal duct most likely needs replacing anyway, probably has condensation on the outside of the metal duct and likely rusted (or at least rusting) out.

"2- Is it even cost effective to do so, would it be better to recommend replacing?"

Better to recommend replacing.

Of course, that now means duct with a higher R value for its insulation, which may mean going to flexible duct.

I saw the neatest flexible duct yesterday at my continuing education seminar - much stronger than the normal flexible duct, could not squish it down to oval, it stayed round. Could not squish it collapsed when making a sharp 90 degree bend - because you could not make a 90 degree bend that sharp, it would not collapse into itself.

Did not sag as much either between supports (because the helical coil around the duct was much stronger).

Of course, it cost about twice as much. It would save on installation time, so the overall job cost would not be much higher, if any ... but we all know that contractor go for the cheapest material available.

Richard Rushing
04-06-2007, 07:45 PM
90% of all metal ducating I have seen under a home (crawlspace) has been sitting on the ground with areas of open insulation.

ALWAYS, ALWAYS... these have had rust on the bottom side at multiple locations.

I would suspect that the one pictured above, in the attic, is in similar condition.

Once the insulation has been opened, the metal will have condensation collect on the bottom and rust out.


Tim Moreira
04-06-2007, 09:29 PM
Looks like either someone has been stomping around up there or the outside skin on the insulation is really starting to deteriorate and fall apart.

I would think it would be better to replace.


Kevin VanderWarf
04-07-2007, 02:12 AM
If a significant amount of the duct system looks like that, I would say the entire duct system should be replaced.
re-insulating whats in the pic would be out of the question.
That duct work is beyond repair.