Inspecting A/C duct work what do you look for

When inspecting A/C duct work on a upflow furnace with the ducts in the attic what do you look for.

Google the air difussion coucil. They have some really good information there.


This link should help you…

Great link David but not what I was looking for.

What do you as an inspector look for as a discrepancy in the duct work that would end up on the repair list of your report.

Attic ducts, at least around here, are flex ducts. I check for separations, tears on the protective (plastic) covering, type of duct (some brands are very flimsy and are not well insulated), flattened areas (some tradesmen will lay on the duct for protection from fiberglass insulation), kinks, excessive length of supply ducts…

Flex duct Bah Humbug: But yes it is something we have to deal with but by no means my preference. There are some brands used here when reaching 15 to 20 years in the extreme heat of the attic that the outer plastic covering breaks down and virtually disappears leaving the inner fiber glass wrap that just pops open as there is nothing to hold it together. Have you experienced this. Whats your take on flex duct in a crawl space.

I don’t care for flexduct anywhere, especially in a crawlspace. Because of the difficulty in working in crawls, installers are usually in a hurry to get it done and get out of there. That leads to some poor workmanship.

Attic and crawlspace installations are also very susceptable to attack by wildlife. Squirrels, rats, foxes, cats, dogs, rackety-coons and other critters can do a number on flexduct. Who monitors these places?? Nobody ever checks to see how things are going under the house.


If the duct work is in tact and the insulation is not exposed and (as Jae already mentioned) not kinked, separated or torn, then that pretty much covers your duct inspection.

Thanks David

I might interject a couple of thoughts of my own that I do with flex duct.

I do a visual check at the plenum and the Wye’s to see if the plastic banding straps were used I refer to this as my quality check as Jae stated other trades will abuse the duct and if bands were not used as they should be this duct will separate. I simply view the overall installation of the duct and if no pride was used in craftmanship with the duct the remaining install is probally the same way. It just kind of gives me a heads up to be watchful in other areas.

Look for stuff like this

Exactly: Great Pic’s