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Asbestos on forced air ducting

user-1023211 | Posted in General Questions on

(Zone 5, Des Moines, Iowa 1,100 sq ft, 1 story with dormer upstairs 1920’s built)

After deciding to finish our basement, I had a radon guy out to look at the house for mitigation since our 2 home tests were a little above the ‘4’ actionable level.

The guy was knowledgeable and looked around and pointed out that we have asbestos ‘paper’ wrapping the old part of our forced air ducts that we should paint over with an oil based paint to ‘contain’ it.

Which got us (wife and self) thinking…if we want to keep asbestos out of the air this is the absolutely worst place to have it, and by painting the outside we are not really addressing the real problem inside the ducts that are blowing this around the house. It’s my understanding that this was applied to seal any gaps in the sheet metal, so those gaps are now where the asbestos mineral is entering the airstream and it really needs to be removed altogether.

So I’ve called an asbestos removal company and am waiting to hear back from them. The only good thing is that it is not all of the ducting, however it is some of the hardest to reach ones, like the one running upstairs enclosed in a wall.

Needless to say we’re employing our electric space heaters until we can resolve this. But I find it funny that I searched and could not find anything related to this topic here, while this is definitely a green building topic as green means healthy air, water, building, etc.

Anyone else have experiences similar? I’d like to know how others have dealt with this appropriately.


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  1. GBA Editor
    Martin Holladay | | #1

    The situation you describe is common. You are doing the right thing; an asbestos-abatement contractor should be able to advise you.

    Asbestos particles don't pose a threat unless they are "friable" -- that is, able to come loose and float around in the air. Asbestos fibers in siding products and flooring products aren't usually friable. However, the fibers in asbestos duct insulation are often friable -- especially if the outer jacket of the insulation has been damaged. (At one point, my parents lived in a house with insulation like that, and I definitely saw friable fibers.)

    If the jacket around the insulation is in perfect shape, you may decide to leave well enough alone. But most homeowners prefer to get rid of the asbestos insulation. Your contractor will tell you how much that will cost.

  2. user-1023211 | | #2


    Thanks for your quick reply.

    Just a bit more info. there is no insulation in our case (you mention insulation). Just this paper, which we haven't had tested, just the radon guy said it was asbestos - which I'll assume it is for now.

    You can see all of the easy access ducts were replaced when the furnace was replaced by the previous owners it appears. We've been here 6 yrs, but never spent any time in the basement and so this was never on our radar of issues to be concerned with until now when we are considering some renovations to turn it into useable space. Anyway I thought the pics could be useful, and as I said the white paper is mainly away from the furnace as the pipes head into walls and hard to access areas.

    Still waiting to hear back from the abatement contractor, I'll call again on Monday if I don't hear back today. Do they usually give free estimates and/or site visits to assess it before quoting the project. I somehow assume they are more used to working in commercial projects than residential so I hope they don't think this is too small a project.

    Thanks again,

  3. user-1023211 | | #3

    Update: So we've found 2 firms that do removal in the area and had quotes for removing the affected ducts. The prices varied from ~$450 - ~$1200.
    So I'm considering the lower priced one (duh) as they said (and I will verify) they are registered with the state for this kind of work and described what they would do which sounded right.

    That included air sealing - taping plastic around the localized areas where the work needs to be performed. Whetting the material well and covering it with plastic, then removing/pulling the ducts out. They would be wearing appropriate personal protective gear with air monitors on their suit to verify what may have been released to the air during the job. There's a bit more to it, but it seemed like they were on the up and up. They also let us know that as a homeowner we can do this ourselves without hiring a licensed company. But for the price I'll just let them deal with this part and I'll try to figure out how to get new ducts ready so we'll be getting heat this winter.

    Also I poked a hole in the wall on the main floor to view the duct that runs to the attic/dormer room and found it's not covered in asbestos paper-(sigh of relief). I guess it's common to only wrap the areas in the basement near the furnace as a fire protection, but I wanted to be sure we'd be getting it all out of the home at once if we're hiring someone to come out at all.

    I thought I'd share what I'm learning on the topic since I really didn't know much about this stuff a month ago and just assumed we didn't have it. So I hope this can help someone else in the same situation (and there are millions in pre-1980's homes out there)! To that end one of the abatement contractors said asbestos is still present today in imported sheetrock, roofing caulks, and a few other building products still used today. I've read they still mine it in Canada and manufacture with it in India for roofing panels, but I was surprised to hear about it's continued use here in the US. (I haven't yet verified the roofing caulk info by looking on the labels at the home stores.)

    Okay, that's all I know as of now, and thanks for all the great information on this site.

    UPDATE 12-26-2011: Job was done at end of November and I installed new register boots (some of which were tricky as they don't make the sizes we have on this house so I had to custom bend some sheet metal) same day and all in all the whole thing was pretty painless.


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