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This document explains when and why it is appropriate to test for mold contamination or actual mold growth in certain insulation in residential and light-commercial buildings.

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.

Here we discuss 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.

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When to test building insulation for mold

We would recommend inspecting and testing building insulation for mold in the following cases:

1. Fiberglass, cotton, or wood product insulation in any building floor, wall, or ceiling cavity which has been wet. In the photo at left some insulation has fallen onto a crawl space floor where it may have been exposed to water entry. All of this insulation, even in the floor overhead, is suspect of mold contamination.
   
   
2. Fiberglass, cotton, or wood product insulation over wet or damp basements
   
   
3. Fiberglass, cotton, or wood product insulation over all crawl spaces
   
   
4. Fiberglass, cotton, or wood product insulation in attics or roof cavities where there has been leakage or where stains show that there has been a history of high attic moisture, condensation, or inadequate ventilation
   
   
5. Fiberglass, cotton, or wood product insulation in building walls subject to leaks from plumbing failures,previous wetting due to building fire extinguishment, or in freezing climates, walls subject to leaks from ice damming.
   
   
6. Fiberglass, cotton, or wood product insulation in buildings if it has been exposed or may have been exposed to high levels of airborne mold or moldy dust and debris from other mold contamination problems or from mold remediation projects, especially if the mold remediation project did not make use of good containment and negative air procedures in the work area.
   
   Certainly test, or simply skip testing and just remove any such insulation that is found inside of a mold remediation project area - such insulation should have been removed as part of the cleanup procedure.
   
   
7. Fiberglass heating or cooling duct material, especially if it has been wet from building leaks or A/C condensate mishandling

When Not to Test Building Insulation for Mold

Fiberglass insulation: I do not recommend routine testing of building fiberglass for mold in non-suspect cases such as where insulation is new and/or has not been exposed to water, dampness, or other mold contamination sources.

"Spot checks" by "mold testing" in buildings, if conducted without an expert diagnostic visual inspection and history gathering, are simply not reliable and thus not cost-justified.

Other insulation materials that are not conducive to mold growth: such as fire-retardant treated cellulose insulation and closed-cell insulating foams are unlikely to be mold-contaminated.

Low-risk buildings where there are no building-related occupant health or air quality complaints: See When to hire a professional to investigate a building for toxic mold for more detailed advice on deciding when it is appropriate to hire a professional or to perform further mold testing in a building.

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FIBERGLASS HAZARDS
  FIBERGLASS CONTAMINATION TEST PROCEDURE
  Recognizing Fiberglass Duct Insulation
  Lab Identification of Fiberglass
  Fiberglass Fragment Hazards
  Fiberglass Detection in Building Air
  Mold in Fiberglass Insulation
  Mold in Foam Insulation
  Moldy insulation may look clean
  Why does mold grow in fiberglass?
  When to test insulation for mold
  How to Test for Mold in Insulation
  Fiberglass Hazard References
INSULATION INSPECTION & IMPROVEMENT

More Reading about moldy insulation in buildings:
BASEMENT MOLD includes examples of moldy fiberglass insulation found in basements
CRAWLSPACE MOLD includes additional examples of moldy fiberglass insulation found in crawl spaces

• Fiberglass building insulation and HVAC duct work insulation hazards
• Fiberglass carcinogenicity: Glass Wool Fibers Expert Panel Report, Part B - Recommendation for Listing Status for Glass Wool Fibers and Scientific Justification for the Recommendation", The Report on Carcinogens (RoC) expert panel for glass wool fibers exposures met at the Sheraton Chapel Hill Hotel, Chapel Hill, North Carolina on June 9-10, 2009, to peer review the draft background document on glass wool fibers exposures and make a recommendation for listing status in the 12th Edition of the RoC. The National Institute of Environmental Health Sciences is one of the National Institutes of Health within the U.S. Department of Health and Human Services. The National Toxicology Program is headquartered on the NIEHS campus in Research Triangle Park, NC.
• Fiberglass insulation mold: occurrence of mold contamination in fiberglass insulation can be impossible to see with the naked eye, but can be significant

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• ...

More Information on Building Diagnostic Inspections and Repairs

For more information about fiberglass as an indoor air quality concern see:

• Fiberglass in Indoor Air, HVAC Ducts, and Building Insulation
• Fiberglass Particle Identification in the Fiberglass Test Laboratory
• Goodman Gray Flex Duct Deterioration and Failures
• Mold in Fiberglass Insulation
• Optimum Indoor Air Filters
• Owens Corning Flex Duct Deterioration and Failures
• World Trade Center Dust Particle Identification

For more information about asbestos as an indoor air quality concern with focus on easy ways to identify asbestos materials in buildings, see:

• Asbestos Identification in Buildings: How to find & identify asbestos-containing materials
• Asbestos in Good Condition
• Asbestos HVAC Ducts - Asbestos Materials On or In Heating and Cooling Duct Work
• Asbestos paper duct wrap
• Asbestos Transite Chimneys, Flues, & Pipes in Buildings
• Asbestos under the microscope
• Asbestos Vibration Dampers & Asbestos in the Air Handler
• Ceiling tiles: How to recognize ceiling tiles that may contain asbestos
• Examples of unusual uses of asbestos in buildings

• Fiberglass in Indoor Air, HVAC ducts, and Building Insulation, Indoor Air Quality Investigations: (this article)
• Mold in Fiberglass, when, why, and how fiberglass becomes a reservoir of problem mold in buildings.
• Lab Identification of Fiberglass photographs and text assist in laboratory identification of fiberglass fibers and fragments in air, dust, or material samples in the laboratory using forensic microscopic techniques.
• Asbestos: How to find and recognize asbestos in buildings - visual inspection methods, list of common asbestos-containing materials

InspectAPedia® Home & Site Map - Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice: In-depth research & advice on diagnosing, testing, correcting, & preventing building defects & indoor environmental hazards. Unbiased information, no conflicts of interest.

The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems

Use this simple, economical mold test kit by following our instructions on how to collect and mail mold samples to our lab

Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.

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