I need to remove the existing ductwork in my basement to install insulation behind it. I'd like to do it without destroying the ductwork. The vertical duct is right against the foundation, so I can't pull it off the end of the pipe: Ductwork

What's the easiest way to do this? On the other end of the horizontal duct, it goes into the top of the main trunk, so it's not any easier to disconnect on that side. Do I just need to suck it up and hacksaw through the round duct, and replace the cut piece?

  • 1
    It's difficult to tell from the image, but it looks like somebody accidentally used duct tape on your ducts.
    – Tester101
    Jan 22, 2015 at 17:28
  • Can you add a photo of the other end of this duct?
    – Tester101
    Jan 22, 2015 at 17:28
  • 1
    Sounds like if you're planning on putting insulation behind it you'll have to cut off some from the round duct anyway. I would cut it off and get it out of the way. Probably could've had it done by the time you made the post :) I don't think I'd use a hacksaw though, tin snips are my weapon of choice for duct. Jan 22, 2015 at 18:22
  • @Tester101 - Yes, lots of duct tape. Once I get the ducts where I need them, I'll be replacing it
    – Drew
    Jan 22, 2015 at 19:26
  • @ChiefTwoPencils - How do I go about getting the tin snips started? I don't have an edge to start cutting at on the round duct
    – Drew
    Jan 22, 2015 at 19:27

1 Answer 1


Chances are the end of your horizontal stack into the box has a lot of tabs that are holding it together. I would leave this in tact. I would remove the duct tape (that shouldn't be used for ducts) and release the two pieces of horizontal duct that are being held together with said tape.

These are probably just smashed into each other and chances are you won't even have to have tools (maybe a screwdriver if they put a couple of small screws in) to remove this. Once you break these two pieces apart you can add insulation on your wall.

Note about the insulation - Please please focus on the lack of insulation I see in your joists above the cement going all the way around. This is way more important that insulating the walls of your basement.

Once you have insulated you may need some tin snips to cut back an inch or two on one of the horizontal ducts. You also may be able to smash the duct into each other sufficiently - this depends on how deep your insulation is. Also if you don't want to deal with cutting metal most big boxes will cut a sheet before they sell it to you. Not sure which one I would take them but possibly the one on the right. But anyway these are dramatically easier to cut when unrolled.

  • Yep, working on insulating the rim joists as well (once I can get the ducts out of the way). The 2 pieces of round duct are help together by a sheet metal screw, but even when I remove that, they overlap by about 1.5", which is more than I can back the duct out since it hits the foundation.
    – Drew
    Jan 22, 2015 at 21:01
  • You should be able to tap them to the side. If you feel one of the other ends will be jostled then you can get a couple of helpers. If that doesn't work, drill a hole and then tinsnips. If you don't have a big bit drill a line of small holes next to each other, use the ends of the tinsnips to get a line cut and then once big enough cut away.
    – DMoore
    Jan 22, 2015 at 21:04
  • Also why does a run end at your wall? Is there a vent underneath the picture? If there is no vent this should be capped closer to the end of the run.
    – DMoore
    Jan 22, 2015 at 21:06
  • I'll give it a try. There is a vent at the bottom of this (one of the few things they did right when they finished the basement the first time, putting heat vents low). A couple other runs are in joist bays so pushing to the side could be iffy, but your point about needing to cut it back anyways to fit inside the insulation makes sense
    – Drew
    Jan 22, 2015 at 22:14

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