Fiberglass insulation mold contamination test details:

This document discusses choices of test methods to screen for toxic or allergenic mold contamination in fiberglass building insulation in residential and light-commercial buildings.

Mold is often found in basement fiberglass insulation, crawl space fiberglass insulation, fiberglass wall insulation, heating or cooling duct fiberglass insulation, and attic or roof insulation in buildings which have either been wet or have been exposed to high levels of mold from other sources.

How to Test Building Insulation for Mold Contamination

This article explains how to find or test for moldy insulation in buildings, the probable cause of mold contamination in building insulation, and how to recognize conditions that make that problem likely in a particular case.

Our page top photo shows a Burkard personal air sampler that with clever manipulation can be used to test fiberglass building insulation for contaminating particles including mold, insect fragments, pollen, or other debris.

This website discusses health hazards associated with moldy fiberglass in buildings, with focus on fiberglass insulation, fiberglass fragments, fiberglass in heating and air conditioning duct work, and invisible but toxic mold growth in fiberglass which has been wet, exposed to high humidity, or exposed to other moldy conditions.

Watch out: Our photo of clean-looking insulation in a basement ceiling (at below left left) does not provide evidence that insulation testing was necessary for that building.

But a case history of occupant complaints, a wet basement, and previous storage of moldy materials in the basement that had been removed at the time of our inspection led us to test and confirm that this insulation was severely contaminated with Penicillium sp. mold.

Reader Question: How should we sample fiberglass insulation for mold when investigating a building?

I believe that there is mold that is not visible to the eye, but how do you confirm that it is there? Send a piece of the insulation to a lab for analysis? I’m a mold inspector in Minneapolis, Minnesota and we have a lot of damp insulation in basements here.

Sometimes I see spots on the insulation and know that there is obvious mold, but I have long suspected (based on smell and moisture readings) that some mold might not be visible to the eye. Is it just that it is in early growth stage so the colonies are too small to see?

And again, how do you verify that this is the case – by samples submitted to the lab? I was on the site searching for information on mold in insulated ducts. - Vickie Swenson, CRMI Minnesota Mold Inspection (612) 508-2742

Answer: Detailed Description of Methods for Testing Building Insulation for Mold

You are quite right that it can be impossible to see mold in some materials including fiberglass insulation. Sometimes fiberglass looks very very clean to the naked eye, but is chock full of Aspergillus or Penicillium.

There are several similar ways to test insulation that does not already give visual evidence of a mold problem.

Air Sampling Cassettes for Insulation Mold Test

We use an air sampling cassette such as an Air-o-Cel or Allergenco unit with a vacuum pump set to move air at the proper flow rate for the cassette (typically 10 lpm). The sampler is held 1-4 inches away from the insulation and then with the pump running we poke or agitate the suspect insulation to stir a particle release.

The sample interval needs to be short - often just 5-20 seconds in duration since otherwise you risk overloading the cassette with fiberglass particles.

At ACCURACY OF AIR TESTS for MOLD we include photos of particle traces on microscope slides that can help you recognize when a dust sample is overloaded and thus hard to analyze in the lab.

Our photo (above left) shows a more complicated version of this test about to start. In this case we were using two air sampling pumps and two different brands of sampling cassettes in order to compare their behavior during dust sampling.

In the foreground you can just make out a special timer-switch that we used to turn on and off both pumps simultaneously.

If you are in doubt or inexperienced, try making three sample cassettes of 5, 10, and 20 second durations, agitating the insulation about the same degree in each case and keeping about the same distance.

The time and distance are not critical as long as we make clear that this is a qualitative test for the presence or absence of high levels of mold or other particles in the insulation, not a quantitative test.

Burkard Personal Air Sampler and Prepared Slide for Insulation Mold Test

A second method for testing fiberglass insulation that we have used with good results was to run a Burkard personal air sampler with a prepared collection slide mounted in the device for a 15-second interval, holding the sampler one to six inches away from the insulation during agitation of the insulation itself.

You can simply use a pencil to poke the insulation during sampling. As with the air sampling cassette approach above, make several test samples at different sampling durations to be sure you have a good sample that is not overloaded.

Alternative, low-cost Air Pumps for Building Insulation Mold Testing

While we prefer using a calibrated instrument for pulling particles from building insulation to screen for mold contamination, considering that a reasonable mold contamination test is qualitative and that precise mold counts are inappropriate (and would be misleading), as long as your air pump or vacuum device produces a flow-rate within the operating range of your sampling cassette or slide, you can use less costly devices such as the keyboard vacuum pump shown here.

Watch out: the airflow rate of portable battery operated pumps such as shown here varies widely from device to device as well as depending on battery condition.

For field use in testing insulation, we tested ten low-cost portable pumps in our forensic laboratory, selecting a subset that consistently delivered 10-15 LPM with fresh batteries .

Constructing a Clean Test Chamber to Screen Insulation for Mold

In the laboratory, if we receive a bulk sample of suspect insulation, in addition to inspecting the insulation itself in the stereo microscope and high power transmitted light forensic microscope, we sometimes use a third sampling method that is most suitable for a variety of suspect, perhaps dirty and loose materials.

We construct a test chamber using a cardboard box lined with a new clean plastic garbage bag.

The bag lines the box, the sample is placed into the box, the box is sealed. We cut an opening sufficient to admit or affix our air sampling cassette, then we agitate the box for 30 seconds before pulling a vacuum sample from the box itself.

This method also can reduce overloading the sample with fiberglass particles.

Quantitative Analysis of Insulation Samples for Mold Contamination

It is possible to perform quantitative analysis of insulation or other fibrous materials or dust samples for mold contamination using a wash and filter method that collects most particles from the insulation sample into a liquid for further processing and particle counting.

We do not agree that the apparent accuracy of this method is real, and we suspect that except for controlled technical studies it is not appropriate.

1. Fungal contamination within a fiberglass sample varies widely even within the same building area depending on proximity to a leak
2. Fungal contamination within fiberglass insulation in a building varies by distance to an external airborne mold source such as moldy contents stored in a basement below a fiberglass-insulated ceiling
3. Fungal contamination in fiberglass insulation in a building will vary by other factors such as insulation age, density, installation details, presence or absence of vapor barriers, air movement patterns, etc.

Therefore a quantitative analysis of mold spores per cubic inch, meter or other volume of fiberglass insulation may be very precise (lots of decimal places) but inaccurate as an estimator of size of the problem mold reservoir.

Should All Building Insulation be Tested for Mold?

No.

We do not recommend testing all insulation for mold.

The decision to test insulation for mold needs to be made based on a careful building inspection and case history, including visual evidence of leaks or the presence of exposed fiberglass over an area known to be or have been subject to a large mold contamination problem or a mold remediation project.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Some of our ceiling fiberglass insulation is moisture stained: is it likely to be moldy?

The fiberglass insulation on the ceiling has some mostly small ( 1 inch by 1 to 3 inches) moisture stains. But there are quite a few sections along the ceiling that i can easily access that have this problem ( probably once on section from roof apex to eaves). How likely is it that it is contaminated by mold? On 2021-06-27 by Holly

Answer by inspectapedia.com.moderator (mod) - check for mold growth on the wall cavity side of drywall that got wet

@Holly,

Drywall is very mold friendly; it would make sense to inspect the hidden side of drywall that

1. has been wet

2. remained wet for 24 hours or longer

and if you find mold on the attic side of ceiling drywall I'd treat that insulation above-it as presumed mold-contaminated too

by Holly

@inspectapedia.com.moderator, there is no drywall on the ceiling. it has the insulation exposed with plastic sheeting underneath.

by inspectapedia.com.moderator (mod)

@Holly

Okay so if I understand you correctly you are seeing moisture on the ceiling or insulation side of the plastic barrier. That tells you that there has already been a problem with either weeks or condensation. Most experts agree that insulation that's been wet should be removed and replaced. I don't think that changing the ventilation system was changed that condition

by Holly

@inspectapedia.com.moderator, Thanks. I agree it is probably from a leak. OK,. so even though somewhat low amount of moisture penetration, still probably best to discard of insulation?

by inspectapedia.com.moderator (mod)

@Holly

IMO replacing suspect insulation is so inexpensive, especially where it's readily accessible, that leaving it in place is not worth the much greater cost of having to do the job over again later because of a mold or other contamination issue.

Kitchen leak leads to mold-contaminated fiberglass insulation

Hi, We purchased our home in 2012, The main part of the home is built in 1940, and the additions were done in 1994.

We had a water leak in the kitchen. We replaced or sistered the joists. Replaced the flooring.

Our bedroom was the next place to do. My husband kept getting sick with respiratory things. I was on oxygen for awhile, then went to a CPAP. But always felt tired, and just not right.

My husband would get up and be coughing and blowing his nose like crazy. I then got to the point that my nose would be itching like crazy.

We had a cold return vent under my bed, that we covered in a clean bag. As there was only a crawl space under the original part of the house. when they added a new living room and 2nd bedroom, they put in a basement. We pulled up the floors in the bedroom. Carpet, newspaper, hardwood floor, then slats of hardwood flooring, that was from the 1910 fire that went through here in Baudette, MN.

It was burnt on one side. Now we are at the joists. Along the wall there is styrene, some concrete for footing and or hard thick wood for foundation. We pulled up the styrene, and it reeked of mold and moisture. There is also fiberglass stuck in here too. This fiberglass changed colors. I wear a mask when I go in there, otherwise I start sneezing.

I have read your articles, how would I go about sending any of this to make sure we know what we have and how to clean it. My husband has a severe nasal infection. We have a north wall that does not get any sun, and is always wet on the outside. Nothing grows there, but moss. On this north wall up into the wall we think it is blown insulation as it just goes to a fine powder and is an off white, in color.

We can see holes in the wood to the outside too. We want to seal all of this crawl space up. There is a fine white powder on the black dirt, in this space also. We now sleep in the garage, that is being turned into a living room, on a slab of concrete. We are way up north next to Canada. It is snowing today. So it is cold a lot.

But you can see the moisture on the dirt inside the wall foundation. Any and all help will be appreciated. sorry can't spell either. Sincerely, Mary Ann Benson 205 5th Avenue SE, Baudette, MN 56623. Do you know if insurance will pay for any of this too? Thank you

PS I love your site, and I gave my doctor some of your articles too, as there are others with old homes too. And no I didn't have a Asthma attack either. Thank you On 2016-03-25 by Mary Ann Benson

Reply by Mod - here's where I'd start to address your concerns

Mary Ann

I would start by reviewing your concerns with your doctor. If knowing more about what's in the dust, air, insulation, and on surfaces in your crawl/now/basement (or other house areas) would be useful to the doc it may be worth hiring a professional to inspect, identify problem reservoirs, and collect a few samples for characterization. (See the EXPERTS DIRECTORY at the top of any InspectApedia page. )

Insulation (fiberglass) that changes color may simply be different brands, different ages, or it may be dirty from air movement or other sources.

"Blown insulation" that goes to a fine white powder when touched is often old UFFI - the out gas hazard would be over by now but you may find that this insulation has shrunk, leaving air leaks and heat loss around the perimeter of the wall bays sprayed with this material.

Basically you want to identify problem reservoirs of dust, dirt, mold, or other substances, remove them, and in the case of leak-related problems such as mold, find and fix the cause.

About insurance coverage: many homeowners insurance policies will include building cleaning and repair, including mold removal, for mold caused by a category of leak that is included in the insurance coverage while other water sources and leaks will be excluded.

PS: I just returned to NY from the north shore of Lake Superior - I know it's plenty chilly in Baudette.

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Continue reading at TEST PROCEDURE for MOLD in FIBERGLASS about just how fiberglass mold tests are conducted in the field or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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• FIBERGLASS HAZARDS - home - building insulation and HVAC duct work insulation hazards
• FIBERGLASS INSULATION MOLD - home
• INSPECTION of INSULATION for MOLD before testing - noting that contaminated building insulation may look clean to the naked eye.
• INSULATION MOLD CONTAMINATION TEST
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• TEST CHOICES for MOLD in FIBERGLASS
• TEST PROCEDURE for MOLD in FIBERGLASS
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• WHEN to TEST INSULATION for MOLD
• WHY DOES MOLD GROW in INSULATION? that includes photos and test results examining suspected mold on the surface of fiberglass-lined HVAC ductwork.

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TEST CHOICES for MOLD in FIBERGLASS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to MOLD CONTAMINATION & REMEDIATION

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