Questions & answers about fiberglass HVAC duct damage as a source of airborne fiberglass fragments:

Frequently asked questions about fiberglass in or on ductwork: fiber shedding, indoor air quality hazards, proper & improper installation, damaged HVAC air ducts.

This article series provides information about fiberglass hazards in heating and air conditioning ductwork in residential and light-commercial buildings.

Recognizing Fiberglass Duct Insulation

These questions & answers about fiberglass HVAC ducts or "air ducts": installation, troubleshooting, damage, fiberglass shedding etc were posted originally at FIBERGLASS HVAC DUCTS - be sure to see the advice given there.

On 2020-04-04 by (mod) - black insulation may not be moldy

Dorian

We don't actually know that the "black insulation" was itself moldy, but I agree that if fiberglass or most other insulation products are exposed to high levels of airborne mold then the insulation will be a remaining mold reservoir from having trapped mold spores even if mold isn't actually growing on or in the material. That's why unprotected insulation might be removed.

HEPA vacuuming the home and using then changing fresh air filters in your HVAC system, perhaps supplemented by duct and air handler blower cleaning are probably in order.

On 2020-04-04 by Dorian Fulcher - mold remediation for stachy bots and aspergillus penicillin. The company was a scam

My house recently went thru mold remediation for stachy bots and aspergillus penicillin. The company was a scam and all the aspergillus is stil the house. I started sleeping in there for a few weeks which I originally had toxic m.old poisoning and I started feialing bad. The ac company didnt clean the return vents or change the insullation or put a filter in them

When I saw the black insullation freaked out, thought it was mold. I asked m.y lawn guy to scrap all the insullation out of the vents. He got out like 90% of it. Hi sungs were burning right after and for a couple days. That night I woke up and my lungs were burning and I was gasping for air hours after I left the house.

I can live in my house now because everytime I fall asleep the same thing happens. I'm afraid the fiberglass went airborne plus the ac company that put the new unit in refuses to clean the vents or replace the insullation. So the unit is running inside my house with what's left of the insullation.

Do you think fiberglass went airborne? And if so how do I proceed to get it out of the air and should I have another company remove what's left of the insulation in the vents professionally and replace it.

Also would the leftovers er insullation in the vents cause the unit to continue to put fiberglass in the air?

On 2020-03-21 - by (mod) -

Jane

You'd need a visual inspection of the duct interior to assess how thoroughly it was cleaned.

Furthermore, I infer from your comment that the duct used interior-insulation. Now you have un-insulated ductwork; so you may need to have exterior duct insulation added.

On 2020-03-21 by Jane

I just had a duct cleaning service do my HVAC system and they found the fiberglass insulation was deteriorated. They pulled out the insulation and then removed what was stuck to the vents using a whip cleaner and high powered vacuum. I called them because of the high level of dust in the house, which they said this removal would solve, but I cannot find any information on safe removal of the fiberglass from the duct work to be sure this work was done appropriately.

On 2019-09-17 - by (mod) -

Yes, Franklin, mold can grow on or inside fiberglass or fiberglass -lined ductwork.

Fiberglass - that is pure glass fibers themselves - are not particularly mold friendly, but given the combination of the organic matter ion normal house dust (skin cells, fabric fibers) and possibly a fiberglass binder resin that might support mold growth in some cases, and the presence of moisture, you could get mold on or in fiberglass ducts. Our article series contains plenty of photos of mold in-situ on fiberglass duct surfaces as well as lab photos of actual fiberglass spores growing along fiberglass fibers.

On 2019-09-17 by Franklin

Can mold grow on fiberglass ducts?

On 2019-05-24 - by (mod) -

Insulation can be a respiratory irritant, I agree, Monica but as it's also normal for house dust to appear as deposits around air supply registers and for it to leave marks as I think I see in your photo, we cannot assume that insulation dust is an issue in your home without more investigation.

On 2019-05-24 by Monica D

I recently moved in to a newly constructed apartment in Florida. My family all seems to be experiencing some degree of irritation ranging from chronic runny noses (inside the house only) to skin lesions and itching. The air quality/mold detection test came back nil and the only other thing I can think of is small chunks of insulation I found in the vents when we moved in? Would this have anything to do with our health?

IMAGE LOST by Comments Box Code error - sorry. If you can re-post the image we'll be glad to comment further.

On 2019-02-23 by (mod) -

Ledlie

You can print the home article of which this page is a FAQs section.

and you're certainly free to give copies of that to your landlord or to anyone else

But you also need objective data if you're going to demonstrate that the duct system in your home is actually a health hazard and that cannot be cleaned and therefore needs to be replaced. You might do that by having some settled dust samples screened for unusual levels of mold or allergens or other problem particles that then are traced to the ductwork.

On 2019-02-23 by Leslie

I recently rented a 1979 condo and had a HVAC guy come to clean the ducts. He said he couldn't because they were 100% fiberglass, it's just a tube of fiberglass. There is no metal casing around it. Every time we put the heater on, I'd start to sneeze which is why we wanted them cleaned. Now, I don't know where to turn. I contacted the city, but they won't come out for ducts. The HVAC guy didn't tell me what he could do as I'm the renter. I would assume they'd need to be changed out, but who would do this in a condo building? What can I do to get the owners to understand this is serious?

On 2019-01-01 by (mod) -

Before hiring a company to clean up the dust in your home, which could be done by any Professional Cleaning Service, you should have an inspector or installer who has a camera inspect your ductwork for damage. If your duct cleaning company used a mechanical method to try to clean the interior of fiberglass lined ducts they may have been destroyed.

That would be a source of fiber glass blowing into the home that would be corrected by replacing such ductwork.

So it would make sense to address that question before during the dust cleanup.

On 2019-01-01 by Roz

I am seeing tiny fragments of fiberglass on my bedroom drawer near the aircon. A1 has just installed a new Rheem airconditioner and I still have the old ducts. The old ducts were cleaned by A1 . Now I have these small fiberglass chards in my bedroom and presumably all over the house , and difficulty in breathing and very allergic swollen eyes.

How do I proceed? Should I replace the ducts? If so won’t the fiberglass still be in the air con system and contaminate the new ducts?
Can you recommend a company that has expertise in cleaning fiberglass from inside the home before I put in new ducts?

Are there companies in Dallas that have expertise in cleaning tiny chards of hazardous fiberglass from my home?
I really need your help.
Kind regards,
Roz

On 2018-06-02 by Lily

I observed dark partials on ground two days ago and did not pay much attention till I saw yellow fiber glass pieces(some big,some small) flow from the vent in my room today. I changed the AC last year. I called the guy who replaced the AC for me and he told me there are some damage in the insulation duct.

But he told me it is very difficult to know where is damaged and ask me to blow hard of the AC till nothing come out. Is he correct? Should I ignore it if nothing came out again or I should do something early to prevent further damage. I live in dallas,TX, if you know some good professional person, please do not hesitate to let me know. Thanks!

On 2018-04-23 by (mod) -

For images of fiberglass or fiberglass lined air ducts start at this page

https://inspectapedia.com/Fiberglass/Fiberglass_Air_Ducts.php

On 2018-04-23 by Anonymous

What should your ducks look like if fiberglass and have them sprayed with fiberlock paint show pics

On 2018-03-01 by Anonymous

Hi!Thanks for your answer.So you don't think that the duct should be changed?I'm seeing in the filter ( that of course alredy got rid of) fiberglasse fragments, so if we can see fibers in the filter that meansthat fiberglass is going through the vents and will be present in the air that we breath at my home, and if the filter got black mold, that could be an indicative of possible black mold contamination inside the duct, or not?

Also in the bathroom's vent it can be see it like the fiberglass in the edges is bulked and is loose. My landlord is going to send a company to clean the ducts and seal the fiberglass lining, but I don't know if that would be enough.What do you think about it? Thanks!

On 2018-02-22 by (mod) -

Romina

Your photos below look like typical fiberglass panel-lined or panel-constructed HVAC air supply register and perhaps ductwork.

One photo looks as if I'm seeing into a foam-insulated building cavity that might be also in use as a supply or return air duct, probably return.
Your last photo (just below) looks like there are dark mold colonies forming on the surface of what you're describing as an air filter. I'd replace that filter.

On 2018-02-22 08:57:14.577162 by Romina

This was a parcial filter that was covering a vent from inside, looks like black mold, right?

IMAGE LOST by Comments Box Code error - sorry. If you can re-post the image we'll be glad to comment further.

Hello, I'll really appreciate it if you could tell me what is your opinion on this ducts. I'm worried for the fiberglass and the mold I'm a renter and lately I'm having the worst allergie ib my eyes, and itchy skin. In this moment I have covered the three vents and turned off the A/C unit. I will contact my landlord to see if the ducts could be replaced.

On 2017-04-03 by (mod) re: what color is the fiberglass in HVAC ducts?

Berenice

Fiberglass insulation is sold in various colors, usually specific to a manufacturer. It doesn't have to be yellow.

But you should not be seeing insulation blowing into your occupied space from the HVAC system. If that's happening fiberglass somewhere in the air path is improperly-installed, damaged, or otherwise defective.

On 2017-04-03 by Berenice

The insulation that is coming in through HVAC system in new mobile home is a darker, almost purple color. Should it be yellow, like the insulation under trailer? Or does it get dirty and turn color?

On 2016-11-27 by (mod) re: how to remove fiberglass from vents and HVAC ducts - blamed on health issues

Coco

You'd have to replace the ductwork. Before going to that expense I'd want to be darn sure that the ducts were the problem.

On 2016-11-26 by Coco

Hi, please can you tell us how to remove fiber glass/glass wool from vents and hrvc ducts and from the house as all in house also and causing health issues. Thank you.

On 2016-10-31 by (mod) re: is it possible to pull remove the fiberglass and put ductwork back up.

Bob,

Please use the page top or bottom CONTACT link to send me photos of the duct exterior and interior and I'll comment further. I suspect I'll end up agreeing that duct replacement will be less costly.

You do not want un-insulated ductwork nor ductwork with shredded fiberglass in the air path. While large fiberglass fragments are not likely to be highly harmful, shredding as you describe the operation is likely to also create small fragments that can be harmful - a health hazard; furthermore, doing nothing or doing the wrong thing at this point risks both health hazards for building occupants and a liability for you as a landlord.

Meanwhile, DO NOT run the air handler / blower. You risk blowing more fiberglass around the home and thus having to do additional cleaning.

On 2016-10-31 by Bob Beltran

I wonder if it's possible to pull out the damaged main and remove the fiberglass and put it back up.

Seems less expensive than replacement, although the stripped ductwork would have no insulation.

It's in the unheated basement. I've taken the end off the main and found the fiberglass is torn to pieces. Just hanging down in strips, rolled or wadded up in places. As I said, one section is almost completely blocked by it. Not sure how to post photos here.

On 2016-10-31 by (mod) re: fiberglass ductwork damaged by "duct cleaning" company

Oh for heavens' sake! Sending a mechanical thrashing type duct cleaning device inside of fiberglass-lined HVAC ducts is likely to cut, shred, and damage the duct insulation. Fiberglass duct liner used inside of ducts is usually coated with a surface sealant to retard fiber release as well as to improve moisture and dirt resistance.

Now I suspect the insulation is damaged, creating several issues: fiberglass release, faster soiling, increased risk of moisture retention, possible mold contamination.

It *might* be possible and feasible to have a specialist contractor apply a spray sealant to the entire duct interior. I would first inspect the conditions inside the ductwork by making appropriate openings at representative locations so that you can see just how much damage and how extensive the damage is.

Your spray sealant contractor should also look at those conditions and should tell you if she expects the result to be acceptable (smooth-surfaced and sealed) or not before proceeding lest we throw good money after bad.

If that approach won't or doesn't work acceptably I'm afraid replacement of the damaged duct sections need replacement. I'm also afraid that faced with that cost your original cleaning contractor is going to run for the hills.

On 2016-10-31 by Bob Beltran - When I turned the system ... gobs of fiberglass debris came flying out

I had the ducts cleaned a week ago in the home we just rehabbed for rental. When the tech discovered the warm air ducts had fiberglass insulation inside, he just poked a hole through it and sent his thrasher in.

When I turned the system on yesterday, gobs of fiberglass debris came flying out most of the vents -except two, which have almost no flow as the main duct serving them is almost completely obstructed by ripped fiberglass. As a presumed professional and the expert in this situation, it seems he should have known better than to have thrashed the fiberglass to pieces. What are my remedial alternatives, and is it likely I hold the contractor accountable to effect a remedy?

On 2016-06-21 by (mod) re: fiberglass is getting into the house from the air ducts

I'm a little nervous about this one.

Indeed fiberglass insulation inside of an air handler or ductwork can become damaged and start shedding - not nice to have that dust blowing into the occupied space.

But a small area of damage to the ductwork or in the air handler ought, in my opinion to be simply repairable - there is a plethora of companies offering spray on magic duct liners that might be appropriate for this situation. I'd sure not accept a $7000. job without much more compelling information. That sounds as if he's replacing the whole rooftop unit as well as all of the ductwork.

That's spending your money to reduce his risk. I've griped about this sometimes un-justified expense as have people even more famous -

see OTHER PEOPLE's MONEY

On 2016-06-21 by Daniel Tomitz

My mom is 80. She had a guy clean her duct out and he said he found fiberglass inside the ducts and was getting in the house. It is a large rooftop ac unit might have some fiberglass linning inside if its torn do you need to replace hole unit for $7000 or can she get it repaired

On 2016-06-21 by (mod) re: suspected fiberglass shiny "hairs" all over the place after roof repair work

Oh darn.

Look, you want to investigate some IFs

IF the roofer made a huge dusty mess that caused debris to fall into the attic - for example he tore off the roof deck entirely, down to the framing, and dropped his junk into the attic -

AND if the attic air conditioning is drawing in air from the attic space (such as torn or open or damaged ductwork)

THEN yeah you need to

- clean up the attic

- fix the HVAC system

- HEPA vaccuum the itchy dust in your house

Meanwhile change your air filters in the AC system

On 2016-06-21 by Natalie

We recently had our entire roof replaced, been running the a/c for about a month now and just recently felt itching, its gotten so bad that my husband has welts on his skin. Upon closer inspection I noticed there are tiny little "hairs" that shine when lights hit them ALL OVER THE PLACE.

After googling I came across this page. I'm guessing it's fiber glass from all the mess made by the roofer? (He wasn't very professional) he left messes all over our garage so I can only imagine what the attic looks like. Any info will be greatly appreciated.

On 2015-10-24 by (mod) re: yes fiberglass can come from HVAC ducts

Yes R.G. it's possible that damaged fiberglass-lined HVAC ducts could be sending fiberglass particles into the occupied space when the HVAC system is running.

Start with a visual inspection of the duct interior - by direct inspection or by using a camera system. If you can, send me photos (see page bottom CONTACT) for further comment.

On 2015-10-23 by R Godfrey

We have had itching on our skin in a room where we had air ducts added when we completed the room. I covered the vents in the room and after completely vaccuming the area the itching seemed to stop. I think that the fiberglass inside the vents is coming apart. Does this seem possible and what can I do to fix this?

Question: how to seal fiberglass duct interiors

(Feb 25, 2014) Anonymous said:
I have solid fiberglass insulation on the inside of my ductworks. It was installed in the 80's, (this ducts are all over Florida) the air conditioner is spreading some fiberglass on the air. Can I seal that fiberglass with a special spray? There is such product on the market?

Reply:

There are spray sealants for duct liners, though these are not an approach that enchants me.

1. First, one would ask why it is necessary. If the duct interior is not damaged its original binder and coating should be intact and it should not be a source of significant indoor air fiberglass. If the ducts were damaged, say by material cleaning, it may be more effective to replace them.
2. Second, if the concern is for mold or similar contaminants, while sealing surfaces surely reduces possible particle release, unless all of the surfaces inside the duct system are visible for inspection it might be risky to presume that a problem has been addressed by a cover-over or coating, and
3. Third if covering harmful particles is essential one would have to be concerned about an adhesion failure, subsequent water or moisture entrapment, and future mold contamination.

While there is surely an application for spray-on sealants, with no other information I'd be nervous about the approach you suggest.

Finally, sure there are encapsulants available. InspectApedia's articles on this topic can be found beginning at

DISINFECTANTS, SANITIZERS, FUNGICIDAL-SEALANTS SOURCES

Question: flooded air conditioner in Costa Rica

(Mar 14, 2014) angela said:
I live in costa rica and have a new westinghouse 3 systems central a/c, but not new air ducts. After many problems with the system and incompetent air conditioning companies here, I have discovered that we have fiberglass air ducts.

Also, after the new system was installed, it was attached to a drain pipe that was clogged and the system completely flooded and water was all over my ceiling and the ceiling almost caved! The ducts also received a lot of water near the actual machine.

After having the system serviced 3 1/2 weeks ago, I started smelling musty, mold smell and went up the the attic (which is small and hard to navigate and veeeeery dirty) and found the entire main duct broken off of the main system (near the filter.)

It happened when the high Unqualified people were changing my filter!! All that dirt, etc was moving through my system. I am very concerned for the health of my children and my family! My children sleep where that system is pushing air!! What should I do? Do I need to change the fiberglass ducts?

They are around 14 years old or more! Also, how to get rid of mold in system? I don't even think the people here know how to service the systems properly! It is making me crazy and very nervous!!! HELP!!

Reply:

Angela, Siento mucho oir de sus problemas con la systema de aire condicionando.

Most likely you will want to replace sections of fiberglass ductwork that were soaked, and to investigate where else water went in the building, as other materials may have become wet and then moldy.

Fiberglass HVAC ducts are an accepted means of air transport but if wet or dirty replacement is the effective option. Attempts at cleaning more often damage the ductwork and increase fiberglass fragment release, and spraying sealants in my opinion creates a lurking time bomb.

Question: replace rigid fiberglass air duct liner?

(Feb 25, 2015) ray said:
can fiberglass be replace in rigid air ducks our some other way to do it

Reply:

Ray

Same answer as to same question you posted at

inspectapedia.com/Energy/Duct_Insulation_Rigid_Fiberglass.php#FAQ

It is possible but may not be cost-effective compared with just replacing the damaged ducts.

...

Continue reading at FIBERGLASS HVAC DUCTS - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Fiberglass duct articles

• DISINFECTANTS, SANITIZERS, FUNGICIDAL-SEALANTS SOURCES if you need to sanitize or seal air duct interiors
• FIBERGLASS DETECTION in BUILDING AIR & DUST
• FIBERGLASS HVAC DUCTS - home
  • FIBERGLASS AIR DUCT MOLD TEST
  • FIBERGLASS DUCT, RIGID CONSTRUCTION

Suggested citation for this web page

FIBERGLASS HVAC DUCT FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to FIBERGLASS HAZARDS

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Citations & References

In addition to any citations in the article above, a full list is available on request.

---

ADVERTISEMENT

---