Asbestos Paper or Cloth Air Duct Insulation FAQs

Identify Asbestos Paper Wrap or Insulation on HVAC Ductwork

Does this look like asbestos paper on an air duct in our wall?

This is wrapped on an air duct in the wall, vertical. I sprayed with water to cut a piece out to send for testing and when cutting it just moved like wet paper. - Anonymous On 2022-05-30

Reply by InspectApedia-911 (mod)

Yes, the pattern and location and use of that paper strongly suggests that this is an asbestos paper duct insulating wrap.

To confirm that it would be important for you to tell me the age of the building and its location. - Daniel F

Is this asbestos wrap on our air ducts ?

Hello,

We recently became aware some of the furnace plenum & duct insulation in the house we are renting may be asbestos. Is it possible to tell from this picture if it's likely asbestos?

There are a few damaged/exposed areas (a corner on the plenum, and an area next to the furnace where the corrugated material has been cut). House is in CA, built in the 1960s.

Furnace seems to have been replaced sometime in the 90s.
Thanks!

Here's a follow-up picture to my previous comment with a close-up of where the corrugated material has been cut / is damaged. Any opinions about whether this warrants concern would be appreciated. On 2018-12-08 by Michael

Answer by (mod) - Yes, that looks like asbestos paper on heating ductwork

From the photographs that looks like an asbestos paper on your heating ducts.

Are these heating ducts wrapped in asbestos paper insulation?

Asbestos wrapped HVAC duct ? On 2026-04-20 by Krysta

Answer by InspectApedia Publisher (mod) - looks like asbestos paper or tape duct wrap

@Krysta,

It does look like it, but as I don't have a closer view to see the paper and its texture, it would be helpful to know the age and location of the building.

Watch out: it also looks as if that ductwork is quite rusted; it may need to be cleaned or replaced.

by Krysta - was original corrugated paper asbestos pipe wrap usually painted?

I have a small question, the original installation of corrugated asbestos wrap was it usually painted with heavy painted surface or mostly just the fibrous look

Answer by InspectApedia Publisher (mod)

@K,

Usually the original surface looked like paper, but by now I'd expect that if you were actually seeing remaining corrugated paper asbestos pipe insulation it will have been painted, perhaps more than once, and often too it was later covered with a fabric; some more recent remediation projects that left this insulation in place may have covered it with a flexible plastic shield, typically white PVC, possibly with banding.

The example I'll show below is listed at Grainger.com but would be available from many other suppliers too.

Bottom line: so you cannot be sure whether or not you're looking at corrugated asbestos paper pipe insulation **except** when viewing it from an uncovered end where, as we show on this page, the appearance is rather unmistakable.

Daniel Friedman

by Krysta

@InspectApedia Publisher, thank you i am just asking generally if the original installation job had paint or not, not that i saw one then ask about the paint

Answer by InspectApedia Publisher (mod)

@Anonymous,

When first installed corrugated asbestos paper pipe insulation was either covered in white paper or sometimes painted or wrapped in cloth, usually white or also painted white.

Since your photo and our prior discussion was about asbestos paper on heating air ducts, please tell me why you're asking about corrugated asbestos paper insulation?

Daniel

What do I do about asbestos paper on this air box?

Reader follow-up to question and answer below, discussing handling of a warm air supply register box whose exterior was wrapped in asbestos paper.

Thanks Dan! What are my options? Abate this box? Or just lax paint it over? I don’t know if there are any wrappers on the connection, it will be my main concern to have part of open tape inside the airflow ;(

Here the photo I can do best without removing grille as they forced to fit in the grille and sealed with caulk.

Seems like it [has none of the asbestos paper seen on the box exterior.]

Quick question: if I just want to abate this ductwork boot, will that cost similar as much bigger work as they still have setup for the entire room, etc? (Feb 1, 2019) James s

Moderator reply

Usually the safest step is to leave the item in place, encapsulating with a suitable paint.

When asbestos paper is on the exterior of a supply register or box the interior of the box is under positive pressure when the heat or A/C is on - so even a small air leak would be trying to blow out, not in, so not trying to draw asbestos particles from the paper into the air supply.

From the ceiling below, remove the grille and inspect the interior of the box; if you see all sheet metal and no asbestos material then there's no asbestos paper in that air path.

Attach a photo of what you see and I can comment further.

I don't see any paper or other insulation or tape inside the box in your photo. Check that to satisfy yourself.

About your follow-up query on removing the asbestos-paper-covered air register "easily":

Fair question to ask the remediator - if it can be disconnected and removed intact in one piece the remediation may be quite easy and inexpensive. If they have to rip things apart - and if you look like a litigious sort or are an attorney - the price will go up.

Watch out: keep in mind that if you see asbestos material in one place it may well be in others - we don't want to have to keep repeating the job.

Tan paper duct wrap might contain asbestos

Inside a bulkhead is a short segment of duct wrapped in brown paper which is torn about 1/2 way along. There's also some dark brown adhesive on the duct and part of the paper. Any idea what it might be? On 2018-11-13 y Ed

by (mod) - brown or tan paper duct wrap: asbestos?

I'm not sure what sort of paper duct wrap is shown in your photo.

It definitely could be an asbestos paper product, though it looks different than the other asbestos papers I've seen and that are shown in this article series in that those usually show an embossed textured pattern

To know for sure what you've got you'd want to have a sample tested by an asbestos test lab.

How thick is asbestos wrap used on ducts or pipes?

Kate

Hi, how thick is the asbestos around old pipes typically ? On 2020-02-25 by kate

Answer by (mod) - thickness may be that of heavy construction paper Or about 1/8" thick corrugated asbestos paper wrap Or thicker (uncommon)

Most common: Asbestos paper such as shown as a wrap around air ducts at the top of this page is like a thick paper. That is less than a tenth of an inch.

Occasional: We've occasionally found (and you'll find in on this page) examples of use of corrugated asbestos paper wrap around round HVAC air ducts, so that's about 1/8" thick.

Rare: we've rarely found thicker asbestos wrapping on the outside of air ducts.

Thickness of asbestos insulation on pipes: You asked about asbestos wrap on pipes.

Insulating pipe wrap may be anywhere from 1/2 inch to 2 inches or more in thickness. And on some occasions we see corrugated asbestos paper similar to that pipe wrap used around HVAC air ducts.

Managing Asbestos-Wrapped Ducts (or pipes) in Walls or Ceilings

The photo above contributed our reader RCR shows asbestos paper wrapping a metal air duct behind wood lath in a building wall cavity.

Our OPINION is that as long as the wrap is only on the duct exterior and as long as it's intact and being left undisturbed, it's in a space where it is generally protected from damage and is not hazardous. -DF.

Identify Asbestos Paper Tape Used on Heating or Cooling Ducts

How should I handle these asbestos-paper insulated air ducts in a 1960's California home?

Due to an unrelated plumbing issue, I've been able to see ducting that I suspect has asbestos in it. Southern California 1964 2 story house. Vertical duct with sheathing separation.

Upon moving in a year ago, the roof ducting was replaced but not the lower level that was inaccessible at the time. Airflow is poor to the upstairs and I can feel many drafts through this plumbing access, so I assume (and can see in places) some ducting holes.

It looks to be metal ducts wrapped with a silver ribbed fiber glass or cardboard looking material which is secured by old white or cream tape which I've been told is probably asbestos containing.

The vertical duct to the 2nd floor has a large section of the ribbed material completely loose from the pipe.

I assume that material is for insulation, not air pressure? I'd like to re wrap using aluminum tape after pulling all the ineffective gray plastic duct tape off, but doing that is pulling off the white suspect tape. Perhaps spraying some kind of sealant in those areas before adding the foil tape over it is the way to go, but I'd have to leave the plastic duct tape.

It would be good to have a stab at tightening up the airflow somewhat for a stopgap measure. The entire AC system needs replacing, which is when I could deal with the 1st floor ducting abatement in a couple of years.

For now though, my wife wants these holes patched and painted, so I'm wondering what I can do now.. I'm also thinking about getting in an asbestos air testing company to test the air quality at the returns, just in case. Thanks On 2022-06-17 by Jonathan H

by InspectApedia-911 (mod) - remedies for air ducts wrapped with asbestos paper or sealed with asbestos paper tape

@Jonathan H,

As we think that those air ducts are at least in part wrapped with asbestos paper, or at the elbows, sealed with asbestos paper tape; it would be smart not to create dust from that material.

I would NOT start peeling things off.

It's perfectly okay to add an exterior wrap if the ducts are acceptable.

The tape on the exterior of a supply duct is on the outside of a duct that's under pressure and therefore unlikely to be drawing any measurable asbestos into the delivery air.

I feel a little different about the asbestos risk for return air ducts that are under negative pressure.

Sometimes it's less expensive to remove a section of ductwork intact and replace it entirely than to start or cause the need for an asbestos remediation job that tries to leave the ducts in place

White tape on my return ducts: Likely to contain asbestos?

Hi, I have found some white tape along my return duct path. Is it likely this contains asbestos? This is the only white tape I have found in my crawl space. On 2021-09-22 by CPH

Reply by InspectApedia Com Moderator

@CPH,

It certainly looks like a white fabric. based tape. I can't tell from the photo if it contains asbestos or not, asbestos joint sealant tape was a paper-like material but there was an asbestos fabric used as a vibration dampener.

If yours is actually an adhesive tape and maybe a newer product.

by Anonymous

@inspectapedia.com.moderator,

Thanks a lot for the detailed replies, I will post back some high res pictures and also try and see if there is any printed info on duct.

This is in San Jose, California and the house was built in 1967-1969 time frame with the ducts being original to the house.

Identify Black or Dark Wrap on Ductwork - Asbestos?

Is there asbestos in this black paper on our air ducts near the air registers?

Found some black ‘paper’ pieces where heating duct ends and sits against the floor joist (saw after removing the heating registrar grille for painting).

The ‘paper’ is unsurprisingly really dry and looks really old. Concerned if it could contain asbestos given its exposure to airflow. Would appreciate any input! On 2021-12-28 by Anna

Reply by InspectApedia Com Moderator

@Anna,

The asbestos paper duct wrap I've seen is white or gray - but I cannot say what your material is;

Knowing more about the age of the material and its country and city of location would be helpful as would be seeing a photo of the source.

by Anna: 1921 home in Washington State

@InspectApedia Com Moderator, thank you kindly for the prompt reply. I’m not sure as to the age of the material, but the house is from 1921, just outside of Seattle, WA.

Not sure if ducts are the original — they are made out of metal and are rectangular if that helps the dating.

The material is thicker than paper, more like a sanding paper thickness but really dry due to heat exposure. Please let me know what you mean by a photo of the source — do you mean the location where I took this piece of material from from? Thank you again!

by InspectApedia Com Moderator - explanation and warning

@Anna,

Yes, knowing where you took that sample will help us understand its intended application. I want to see the ducts

But

Watch out: if that's asphalt-impregnated paper, also referred to as roofing felt or "tar paper", often those products contained asbestos. It's not highly friable - not at high risk of shedding asbestos material if it's in good condition, not being disturbed, and is not inside the air duct or air handler in the air path. - DF

 

Identify Corrugated or Heavy Asbestos Insulation on Heating or Cooling Ducts

Is this corrugated cardboard paper pattern material on our ductwork asbestos?

Does this look like asbestos? I cannot tell if it appears to be damaged/hazardous or not. On 2018-06-03 by Ashley

by (mod) - Yes: asbestos corrugated paper used on HVAC duct exterior

Yes that is asbestos - corrugated asbestos paper is rather definitive in its appearance.

We can say that with reasonable confidence without actual asbestos testing because in over six decades of research and study and forensic field and lab work on this topic, I have not found another duct wrap insulating material that looks like this and that was NOT an asbestos paper product.

It would be helpful to know the country and city and age of the home where your corrugated asbestos paper wrapped ductwork is installed.

And yes I agree that the material is damaged. If that is the only area of damage it's small and limited: cleaned up by HEPA vacuuming and damp wiping.

It's also important to protect the duct insulation from further damage or disturbance. - DF

Are these corrugated paper insulated air ducts dangerous? Should they be wrapped? Do we need to replace the whole HVAC system?

Are theses pipes dangerous and if so should they be wrapped?

HVAC person said our ducts have asbestos and told us we need to change the entire system / home.

Are there any options around encapsulating or painting over it? Or are these holes / disturbances serious enough to even need to address?On 2021-09-28 by Andrew

Advice by InspectApedia Com Moderator

@Andrew,

Looks like corrugated asbestos paper duct or pipe insulation - you'll see similar and rather distinctive-looking pipe wrap at ASBESTOS PAPER DUCT INSULATION

It also looks as if other pipe insulation has been either re-insulated or covered / encapsulated.

Some of your photos show that the insulation is in an area where it's exposed to damage. It'd be smart to protect it - encapsulate or cover it.

About your HVAC tech saying you have to replace the whole HVAC system

@Replace entire HVAC system?,

You can encapsulate asbestos in many circumstances although if that's all Air ducting and not piping that I'm seeing in your photos, and considering the need for future maintenance, it might be about the same cost to simply remove it intact.

It's not like asbestos on hydronic or hot water heating pipes, it's asbestos on ductwork that can simply be removed in sections.

That should reduce the asbestos handling cost considerably.

Bottom line: In my experience the cost to remove asbestos-wrapped duct insulation and then clean and re-insulate the ductwork is about the same as the cost of having all of the ductwork removed intact and replaced with new air ducts, and the latter, in that case, is usually a smarter choice. - Daniel

by Replace HVAC system? - how urgent is the need to address this duct asbestos concern?

@InspectApedia Com Moderator, thanks for your reply.

Is this generally seen as an urgent safety hazard? I'm in the bay area and changing everything will cost $10K+. Would like to avoid cost if possible.

by Replace entire HVAC system? - thanks for the balanced advice!

@InspectApedia Com Moderator, thanks for the balanced advice!

We just got two HVAC companies to come look, and all of them recommended to change(no surprise), prices varied wildly from $7K to $15K (metal ducts). I suspect your feedback on "urgency" impacted the quote.

This is my personal home we just bought and I don't expect to disturb them. The only concern is that it that those ducts are exposed in the garage which we use frequently.

I'm going to do a quick wipe down with a damp rag, and wait until we do a larger Reno to fix this. Thankfully our return ducts don't have this wrapping, only all the runs do.

by InspectApedia Com Moderator - opinion on urgency of addressing asbestos on your ductwork: here's what a medical forensic expert might say

@Replace HVAC system?,

How urgent is the replacement of your asbestos-covered HVAC duct system and how dangerous is it to building occupants?

Certainly reasonable questions to ask.

A fictional but nevertheless expert and smart medical forensic detective (Thorndyke) remarks in Richard Austin Freeman's (1862-1943) "The Vanishing Man ..."

... there is no use in speculating a priori; we should have to reconstruct a purely imaginary situation, the circumstances of which are unknown to us, and we should almost certainly reconstruct it wrong.

With that warning in mind, you will understand that we know nothing about your home and the area where these ducts are located - nor the extent of prior damage nor how any debris has been cleaned-up. (Damp wiping and HEPA vacuuming are safest.)

So you may not want to put your building occupants at risk by website or email consulting that asks "are we safe" - one cannot know.

Asbestos isn't like a radioactive hazard. It's dangerous when it's disturbed to make airborne dust. The EPA points out that asbestos is safe and legal in homes and is usually safest left alone and covered over.

IF there were friable asbestos right in the air path - such as a return air duct, that's a greater concern.

IF there are ducts being damaged so as to create dust, that's a greater concern.

Watch out: In any event you don't want to be scared or breathless when you call contractors for remediation efforts or the cost of the job will be greater, still.

Indeed an essential point about asbestos-wrapped ductwork is that it is generally less costly to remove the duct intact, in sections, than it would be to pay someone to try to remove the asbestos wrap.

I'm also glad that we don't have asbestos wrap on the return air ducts as those are generally under negative pressure so that if there were a hole or opening in the ductwork that exposed the asbestos wrap, there could be some possibility of pulling a bit of that into the air stream.

Protect the duct wrap material from damage. - DF

 

Identify Asbestos Cloth / Fabric on Ductwork

This fabric or paper wrap on ductwork looks like asbestos

Thanks for the quick reply and helpful info! We'll explore encapsulation work with a local certified company. On 2019-11-03 by Anonymous-

by (mod) - ripped asbestos paper ductwork in the crawl space

Ben

I see what looks like an inch or so diameter hole cut in what looks like asbestos paper duct wrap;

That amount of damage is likely to be trivial, that is, not producing detectable release of asbestos into the rest of the building; nevertheless it'd make sense to have some encapsulation done; for paper duct covers some asbestos companies simply paint the surfaces with an encapsulant.
Yes it could be wrapped.

A more serious hazard would be present if asbestos material is in the air path such as inside of ductwork or inside of an air handler, OR if asbestos material that's friable is or can be tracked about the building.
FYI, No I'm not a certified asbestos remediator.

by Ben

I discovered ripped asbestos paper ductwork in the crawl space of the house we've rented for many years -- the rips weren't there until recently, maybe from some critter who got into the space when we left the door open (?). Our landlords maintained over many years the intact paper wrap was fine -- outer insulation over the furnace outtake, just leave it alone.

It just doesn't look intact anymore from my visual inspection. The photo shows one section, but there's similar small rips up and down about 30' of ducting.

Should I be worried? Should these be professionally wrapped or fine left alone?

Thank you so much for your expert opinion!

 

Identify Asbestos Paper Tape Used on Heating or Cooling Ducts

Asbestos paper tape on metal ductwork joints & connections

We are seeing black dust coming out of vents and got a duct cleaning company and an HVAC to come out. Duct cleaning said ducts are in great shape and the black dust is due to dust on the inside getting burnt by the furnace, and just need to be cleaned.

HVAC said the ducts are cracking and has asbestos paper wrapping and need to be fully replaced along with furnace, and that the black dust are attic dust getting pulled in from the crack. What are the right questions or right person I can ask to see who is right? Thanks! -Wendy

Hi, we have black dust coming out of the vents, and got an duct cleaning company and an HVAC company to come take a look. The duct cleaning company said the ducts are all metal and in great shape and cleanable, that the black dust is due to dust on the side getting burnt on the furnace, so we just need to clean it.

The HVAC came and said the duct has cracks and it has asbestos paper wrapping, and that we need a full replacement of duct and furnace. So each company is trying to sell their service. What are the right questions I can ask to figure out who is right? Thank you! -Wendy

Answer by (mod) -

Wendy

This looks like an older home that has been refurbished, including a roof-over with new OSB decking; the ductwork is shiny and new looking; yet I see what looks like asbestos paper duct wrap sealing the duct joints, partly taped over with duct tape.

While standard advice is to leave asbestos materials alone and cover them over, on damaged ductwork that advice might change;

If that material is as claimed damaged, it will probably be least expensive to have the ducts removed and replaced.

You can of course have a sample of the material tested by a certified asbestos test lab (Search InspectApedia.com for that phrase)

Rust-stained asbestos paper duct joint tape may be red or brown or dark

Here are the pictures we took of the flue. Is this asbestos? We think the furnace was manufactured in 1985, so how would asbestos have been used in the flue (did asbestos not get banned in 1977)? On 2018-07-04 by BobbyS

Does this flue have asbestos paper? Also the boot - is that asbestos as well? The paper seems to be fraying in some places - do we need to do an immediate remediation on it? If this is asbestos, we were hoping to change the furnace next year and do the abatement at the same time.

Also, one more question if you don't mind: how do we find out if our ducts (that are behind dropped ceiling covered with drywall) have asbestos in them (insulation or sealing)?

by (mod) - rust-stained asbestos paper duct wrap

Bobby, the photos are a bit small and not so sharp but we in my OPINION we are looking at an asbestos paper or fabric duct insulation that has been wet or stained by rusty water.

About the possibility of asbestos inside of this ductwork (which is possible but unlikely) your best approach would be to hire someone who can use a duct inspection camera to scope out the interior of the ductwork.

Watch out: I'd be alert for the source of and possible damage or mold contamination caused by water leaks into the ductwork. - Daniel

Should I be concerned about this asbestos paper gasket at HVAC duct joints?

What is this product? The professional home inspector made no mention of this in his report. It is in plain view. Should I be concerned? On 2018-10-24 by Andrew

Answer by (mod) -

Andrew,

That looks to me like a bit of asbestos-based paper used as part of an HVAC duct connector or joint. It appears to be on the exterior of an air supply duct (as I see a duct damper lever).

Duct supply air wants to blow out rather than draw into the duct at any joints or leak points.

In my OPINION that means it's not likely that the inch or so of asbestos-paper that we can see is producing a detectable level of asbestos in the building's air sent through the supply duct.

Asbestos paper or other asbestos products that are actually exposed in the air path are something that I'd want removed; usually the least costly approach is to simply remove the duct materials intact and undisturbed and to install new ductwork.

Are these foil-wrapped ducts an asbestos hazard?

Hello! I have some old ducting from 1969, I can see the white asbestos tape at some of the joints and the Butte, but I am not sure whether the duct itself has asbestos, this is a house I just purchased, and the duct is crushed at a few places and a little broken,

So I’m worried about using it if the duct itself contains asbestos, can you please take a look at the attached picture and guide me as to whether the duct material itself has asbestos? On 2021-07-28 by Sam

Reply by inspectapedia.com.moderator - possible asbestos in this ductwork - look closely & compare with fiberglass

@Sam,

From what I see in your second photo that offers more information, it look as if this is a thin insulating material wrapped on both sides with a fiber reinforced aluminum material; indeed there are some asbestos duct products that were made using hemp, nylon, sisal or other fibers for reinforcement of an aluminum foil or metal covering and lining.

At ASBESTOS DUCTS, HVAC

in a section titled Asbestos Liner Inside Metal HVAC Ducts you will find a photo of HVAC ducts that combined metal, or metal foil, and asbestos, that look much like the duct in your second photo.

We have posted more of your own pictures of foil-covered asbestos HVAC ducts there too. From the stamps on your ductwork it looks as if this product dates from 1967.

In your first photo, those long yellow fibers and those fibers in the tape or surface that are arranged in a rectangular grid pattern are not asbestos. More-likely a synthetic material or jute or fiberglass;

But in that first photo the edges that are torn are very white and look like fine fibers that I thought could be an asbestos paper product.

Your ducts are a product very similar to the Asbestos-and-metal or metal foil duct example I just cited above.

Fiberglass is easy to identify in a sharp, well lit photo;

Examples are at FIBERGLASS INSULATION IDENTIFICATION & PROPERTIES

Asbestos paper is illustrated above on this page.

Other asbestos forms are at ASBESTOS DUCTS HVAC at the "Continue reading " suggested link at the end of this article.

and for comparison also see ASBESTOS PIPE INSULATION

It would be helpful to know the country and city of location of the building where this duct is installed
and
to see some sharp high-res photos of

- the edges of the ductwork where those are exposed

- the interior of the duct

- any labels, stamps, markings on the ductwork

adding: by its pattern that looks like a burlap or jute or hemp fabric.

by Sam (mod)

@inspectapedia.com.moderator, thanks for your helpful reply. Here is the zoomed out picture. yes, the prior picture was of the tape removed from the area where duct is crushed.

There is no metal duct inside.

Do you think the white/yellow material in previous picture is asbestos or more likely some other ducting material like fiberglass/cardboard? Or maybe it is fiberglass wrapped in asbestos?

Reply by (mod) -

We need to see the edge or another point showing the actual insulating material under that foil. Fiberglass and most other duct insulating materials are easily identified by eye.

Duct Tape Over Asbestos on Heating or Cooling Ducts

Duct tape over white paper tape on ductwork: Asbestos? Hazardous?

Hi, we have what looks like multiple types of tape on parts of our HVAC ducts. One looks to be white. The other looks more yellow in color that may have silver backing that is peeling off. On 2021-05-03 by ANW

Not sure if this silver backing is just duct tape that was added over the tape at a later time. Any thoughts if these products likely contain asbestos? Home was built in the 1930s. Thanks

by (mod) - duct tape over asbestos paper duct joint tape

@ANW,

That white paper looking material is most-likely an asbestos product: asbestos paper duct tape used at joints in metal ductwork.

It has been taped-over with modern duct tape. The modern product doesn't contain asbestos.

What's surprising is that the condition of the galvanized metal at left in the photo looks so good but it doesn't look old enough to have asbestos paper tag connections.

But sometimes metal duct work in a clean dry attic can stay quite new-looking for decades.

Cover those suspect asbestos-paper-taped joints with foil or other duct tape material or when you need to replace them simply remove them entirely rather than disassembling.

How to best fix loose duct tape on my HVAC Ducts?

I have loose duct tape on the ducts In my basement. It used to just be one loose piece, but now all three ducts have loose tape. How much do I need to worry?

It will be a while before I can afford to have it removed. No one but me goes in the basement. Do I need to really worry about the fibers getting up into the house? Type asbestos duct work in Google search, and the first 100 results are lawyer ads telling you you're surely gonna die! On 2019-08-19 by Nate

Suggestions by (mod) - foil tape has good adhesion for covering small areas of loose duct tape on ductwork

Nate:

I'm not sure what's the worry with loose duct tape except for air leaks in the ducts UNLESS someone used duct tape in an amateur effort to encapsulate asbestos-paper covered metal ductwork.

I can't say "how much to worry" about a building that - from here on the southern side of the trump wall - I cannot see. If there is soft friable asbestos material blowing around the building of course that's a concern. If you can just tape up some loose tape ends, that sounds easy to me.

If that's your situation, and if there are just some loose tape sections here and there, why not pick up some new tape and cover the loose areas again.

I prefer metal foil tape to traditional fabric-based "duct tape" - I find that the metal foil has a stunningly sticky strong adhesive, sticks well to itself, and being aluminum foil, has a perm rating of nearly zero.

You can pick up aluminum foil tape at any building supplier, hardware store, and some plumbing and HVAC suppliers as well as from online vendors. An example is shown below.

If you'd like to post some photos of your hanging chad I mean hanging duct tape ducts I may be able to comment further.

Hazard of Asbestos Materials Inside Heating or Cooling Ducts

Best way to seal Exposed asbestos insulation inside of Air Ducts

Thanks for the information here. I noticed yesterday when cleaning the registrars (the vents) in our 100 year old house, that the ductwork metal inside the registrar had peeled back a bit in a few places and exposed a paper like wrap.

Thus, the positive heating (and summer cooling) airflow will go right by this exposed paper wrap when entering the upstairs bedrooms. There are maybe six five-inch long places where this paper is exposed to airflow (see example photos).

I understand from above that asbestos in this paper is likely, and that inside the ductwork/registrar is a really bad place for this.

This air duct view is inside the vent of the boys bedroom, thanks

Since we are talking about five or so places for this, do you think some Kilz primer and then aluminum tape covering will do? Taking these materials out might also involve disturbance of the asbestos. Thoughts appreciated. -Joe On 2019-12-30

Answer by (mod) -

Joe

With the apology that nobody can give completely confident, safe advice based on just photos and text - as there are always additional onsite factors to be discovered -

it looks reasonable that ***IF*** you can clean the surrounding metal so as to be dead confident that that foil tape will bond well and stay bonded to the duct surface, sure it makes perfect sense to tape the exposed asbestos at duct joints to get the asbestos out of the duct air stream.

I've found that aluminum foil tape is quite sticky and usually bonds well to clean dry surfaces.

Watch out: I also see rust that could raise a worry of water or condensate or leaks into the duct system.

by Joe

Thanks for the advice! I was thinking that I would first use ABC Fiber spray and then after drying to use the aluminum foil tape.

So a double method so to speak. Does that sound reasonable, or would you simply go with aluminum foil tape? Much appreciation for responding so quickly!! -Joe

p.s. as for the rust, there have not really been leaks in our time here. This could just be the share age of the metal--100 year old house--and a relatively humid climate in the summers.

by (mod) - using foil tape on ductwork

The best bond for the foil tape will be to the metal ductwork. I'm less confident with your approach.

If you want to double coat, see if the spray will adhere after the metal tape is in place - test that it doesn't have solvents that loosen the tape.

About leaks into the ductwork: the ducts looked as if there's a bit of rust, and I thought I saw wet areas in two of your photos but of course it could be something else spilled into the duct system.

Is this asbestos visible from inside of our metal ductwork?

Can someone please tell us if this looks like some asbestos tape or some harmless insulation backing peeking from at the outside of the metal ducts we have into the inside of these metal ducts?

We found this when the register grille was taken down for painting the room.

The metal ducts are all enclosed in the dropped ceilings except for in the furnace closet where some asbestos tape was found on the furnace to plenum connection under some later added regular duct tape.

The tape there is also intact, but is being abated. The house was built in 1970. Visually, the material seems intact - not fraying or peeling apart. It is definitely bit yellower than the tape on the furnace.

Therefore wondering if it could be the Two Part Duct Sealing tape that Hardcast sells and was selling in 1970?

Is this a hazard to leave it in such a location peeking into the duct? Have we been inhaling asbestos for the last several years? Very worried.

Also, if it is asbestos, what is the best way to seal or encase it, if any? Use the HVAC mastic tape + mastic at the joint that is right ahead of this material without touching this material so this material is sort of sealed in again?

Or do all the ducts need to change - this is huge work as the ducts are all inside dropped ceilings and drywalls - so a lot of demo.

Much appreciated.

Here is another image of the same duct. On 2019-01-24 by Pini

by (mod) - asbestos-suspect duct tape or duct wrap exposed at duct interior?

Pini

That could be an asbestos paper duct joint wrap, exposed on the duct interior. A photo from the exterior would be helpful and key would be

the country and city of the duct (and building) location

The building age

and if known , the age of the ductwork

 

Possible asbestos and dirt inside heating air supply register in 1974 home

I lifted up the heat duct and found this! Does it look like asbestos? I have 5 kids in my house opinion please! It is the in floor heating in our basement.

The house was built in 1974. We just had the heater replaced 6 months ago. Not sure if they looked at the vents. On 2019-01-21 by Concerned mom -

Answer by (mod) -

Concerned

I see what looks like a heating air supply register that is filled with dirt and debris. Possibly also some building insulation. It would make sense to have the duct system inspected and if it's all metal as I see in your photo, professionally cleaned.

No one can assert with certainty the presence or absence of asbestos from your photo but it's possible. A more thorough inspection of the accessible and visible sections of ductwork and of the air handler can make a more informed guess about that question.

Asbestos Duct Insulation Encapsulation Q&A

Who do I hire to encapsulate this damaged asbestos duct wrap?

Who do you hire to encapsulate it a plumber? On 2018-02-08 by Carol

by (mod) - plumbers do not handle asbestos encapsulation; use an asbestos remediator to encapsulate OR completely remove the ductwork and an HVAC contractor to install new ductwork

No, Carol not a plumber.

Depending on where you live, asbestos abatement is done by licensed contractors.
You'd hire a certified, licensed asbestos abatement contractor to remove the old asbestos material and to do what cleanup is needed.

You might then use a heating contractor to install the replacement ductwork or some abatement companies also can handle that step.

You'll read in other FAQs on this page and in our other asbestos on ductwork articles that often the cost of removing the asbestos-suspect insulation on ductwork combined with proper cleaning and re-insulating is as costly or even more costly than having the ductwork completely removed and replaced with new insulated material.

In part that's because removing duct sections along with their insulation requires less labor and disturbs the asbestos material much less than trying to remove it from the existing ductwork. - Daniel Friedman

Examples of Hardcast Non-asbestos Duct Joint Tape Sealer

Is this HVAC Joint Tape Asbestos?

This tape was around a joint in the HVAC. Apparently it lost adhesion over time and came off. The house was built in late 60s. On 2021-05-02 by FMG

Reply by (mod) - Your duct joint tape looks like Hardcast duct joint sealer, not an asbestos product

That could be an asbestos fabric used on ducts or duct joints, and continuing to speculate perhaps the color tells us that it's been painted.

The coarse weave and uniform coating of the fibers themselves suggest that this may have been Hardcast - a non-asbestos duct joint sealer.

Hardcast duct seal as it was installed in the 1960s and 1970sReferred to as a "two part liquid/tape method", a white or gray fiberglass-bearing cloth tape that was cut into easy-to-handle lengths of about a foot to 18" long (longer for larger diameter ducts, and then applied by dipping the tape into a container of rubber mastic before wrapping it around the ductwork joint.

In other installations the tape was wrapped around a duct joint and then painted with a sealant.

Watch out: we cannot absolutely identify the manufacturer or product from just a photo, and some of these tape products contained asbestos, so you should avoid creating hazardous dust by tearing, sanding, etc. the material.

Currently Carlisle HVAC continues to produce what the company calls "true mastic" Hardcast (R) sealant tapes that are used on ductwork, as we illustrate below.

These products use a butyl (rubber-like) mastic and are currently sold in rolls rather than as strips of fabric that had to be dipped into a container of sealant.

Here is an example of Carlisle's current Two Part II Duct Duct Seal [PDF] (2013) (at coburns.com website) - local backup copy saved as Hardcast-Instructions.pdf Carlisle USA: 900 Hensley Lane, Wylie, TX 75098 • (877) 495-4822 - Carlisle Canada: 2100 Remembrance Road, Lachine, QC H8S 1X3 Tel: (800) 544-5535 Website: www.carlislehvac.com and for our European readers here is Carlisle CM Europe's Hardcast Adhesive Tapes information (website)