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ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
ASBESTOS IDENTIFICATION IN BUILDINGS
FIBERGLASS HAZARDS
  Recognizing Fiberglass Insulation
  Recognizing Fiberglass Duct Insulation
  Lab Identification of Fiberglass
  Fiberglass Fragment Hazards
  Fiberglass Detection in Building Air
  Mold in Fiberglass Insulation
  Actual mold growth in insulation
  Moldy insulation may look clean
  Why does mold grow in fiberglass?
  When to test insulation for mold
  Fiberglass Hazard References
INTERIORS
INSULATION & VENTILATION INSPECTION & IMPROVEMENT
Insulation Materials
  Asbestos Identification in Buildings
  Asbestos Pipe Insulation
  Asbestos-Free Insulation Materials
  Balsam Wool Batt Insulation
  Cotton Insulating Batts
  Cellulose loose fill insulation
  Concrete insulation, light-weight
  Fiberglass Insulation
  Foam Board Insulation
  Foam Insulation Types - Visual Id
  Homasote & Other Insulating Board
  Icynene Foam Spray Insulation
  Insects & Foam Insulation
  Mineral Wool - Rock Wool Insulation
  Mold in Fiberglass Insulation
  Mold in Foam Insulation
  Paper Duct Insulation
  Perlite Insulation
  POLYISOCYANURATE FOAM INSULATION
  POLYSTYRENE FOAM INSULATION
  RADIANT BARRIERS
  RIGID FOAM USE INDOORS
  Urea Formaldehyde Foam Insulation UFFI
  URETHANE FOAM Deterioration, Outgassing
  Vermiculite Insulation
HEAT LOSS CALCULATIONS
INSULATION LOCATION for BASEMENTS
INSULATION LOCATION for CAPES, CRAWLSPACES
INSULATION for GREENHOUSE or SOLARIUM
INSULATION MATERIAL IDENTIFICATION GUIDE
INSULATION R-Values & Properties
ASBESTOS: Photo Guide to Materials / Products
Mold Growth Resistance of Foam Insulation

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Chopped fiberglass insulation in a modern atticBasic Properties of Fiberglass Building Insulation
InspectAPedia®  -    

  • Characteristics of fiberglass batts or chopped fiberglass used for building insulation
  • Photo guide to identification of different building insulation materials
  • Properties of different building insulation products
Our site offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/appointment.htm.

This page illustrates and describes common fiberglass insulation materials. I've added these examples because of frequent questions about these materials. This document assists building buyers, owners or inspectors who need to identify asbestos materials (or probable-asbestos) in buildings by simple visual inspection.

We provide photographs and descriptive text of fiberglass building insulation products to assist in identification of definite, probable, or possible asbestos materials in buildings. In some cases the resin binder which gives color to fiberglass insulation can permit an educated guess about the brand or manufacturer of the fiberglass insulation.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

How to identify FIBERGLASS INSULATION in Buildings

A Color Key to Identifying the Brand or Manufacturer of Fiberglass Building Insulation

photo of balsam wool building insulation photo of balsam wool building insulation
photo of balsam wool building insulation photo of balsam wool building insulation

Our photos above show several colors and forms of fiberglass building insulation. Fiberglass building insulation is commonly installed in batts or chopped forms and may be yellow, pink, green, or white in color as is shown in these four photographs. Under the microscope fiberglass fibers are colorless or clear. It is the resin binder used by the manufacturer to stick the fibers together into a batt or a chopped piece of insulation that give fiberglass insulation its characteristic color. For example our lab photo below shows yellow resin binder.

  • Yellow Fiberglass Insulation: most fiberglass insulation manufacturers other than the ones listed below produce yellow fiberglass insulation. (China Fiberglass Insulation Manufacturers, for example.)

  • Pink Fiberglass Insulation: Owens Corning Pink Fiberglass (R) is a registered trademark for their product line.

  • Green Fiberglass Insulation: John Mansville has produced green fiberglass insulation.

  • White Fiberglass Insulation: John Mansville produces white insulation including their ComfortTherm(R) encapsulated batts.
  • Thermal bypass stains on fiberglass insulationBlack Fiberglass Insulation?: No black fiberglass insulation product has turned up in any of our research. You might see "black" on fiberglass insulation in these forms:

    • Dust and dirt may be deposited on fiberglass as air (containing house dust or other debris) moves past fiberglass at air leaks. In our photo at left you can see some pretty old and extensive thermal bypass leak stains on insulation in an attic. In our photo below at insulating characteristics you can see the very beginnings of such staining on a white fiberglass batt. If you see dirty or black marks on fiberglass it's probably a thermal bypass leak.

    • Asphalt-like black tarry substances may be used on the side of kraft paper or foil vapor retarders used to adhere the fiberglass batt to the paper or foil

    • Black-looking mold may grow on fiberglass that has become dirty and wet, or it may be found more often on the kraft paper attached to fiberglass if that material has been wet - don't blame the fiberglass, blame building leaks on this problem.

Insulating Characteristics of Fiberglass Insulating Batts & Chopped Fiberglass Insulation

White fiberglass batt

Fiberglass building insulation typically has an "R" value of 3.14 per inch.

Fiberglass Insulation is a glass fiber product and does not normally contain asbestos, though it can become contaminated by rodents, insects, or mold, and especially if damaged, disturbed, and exposed to a living space, it can become a source of problem particles, as we discuss at FIBERGLASS HAZARDS.

(In process)

Forensic Laboratory Photographs of Building Insulation

Lab photo of building insulation

Laboratory photos of fiberglass can often assist in determining where fiberglass fragments and debris are originating.

The microscope lets us identify the color of resin binders which may enable us to match the colors in fiberglass dust to the colors and binders of samples taken from known fiberglass insulation reservoirs in the building.

Our own field investigations find that fiberglass particles are quite common in indoor air. Unless the forensic particle laboratory is making a point of counting small fiberglass fragments in indoor air or dust samples, only a large-particle count may be provided and the presence and potential effects of fiberglass dust may be underestimated.

Furthermore, proper lab procedure and use of mountants with an appropriate refractive index to see glass fragments is critical as otherwise such particles may simply be invisible when viewed using conventional slide preparation methods.

A Guide to Health and Debris Characteristics of New versus Old Fiberglass Building Insulation

Dirty old attic insulation

Some research argues that fiberglass particles are larger than and less dangerous than asbestos. However many small fiberglass particles may be in indoor air but may be below the threshold of some common measurement methods. See FIBERGLASS HAZARDS in buildings.

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

  • Fiberglass building insulation and HVAC duct work insulation hazards
  • Fiberglass carcinogenicity update: "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.

    Following a discussion of the body of knowledge, the expert panel reviewed the RoC listing criteria and made its recommendation. The expert panel recommended by a vote of 8 yes/0 no that glass wool fibers, with the exception of special fibers of concern (characterized physically below), should not be classified either as known to be a human carcinogen or reasonably anticipated to be a human carcinogen. The expert panel also recommended by a vote of 7 yes/0 no/1 abstention, based on sufficient evidence of carcinogenicity in well-conducted animal inhalation studies, that special-purpose glass fibers with the physical characteristics as follows longer, thinner, less soluble fibers (for 1 example, > 15 μm length with a kdis of < 100 ng/cm2/h) are reasonably anticipated to be a human carcinogen for the listing status in the RoC. The major considerations discussed that led the panel to its recommendation include the observations of tumors in multiple species of animals (rats and hamsters). Both inhalation and intraperitoneal routes of exposure produced tumors, although inhalation was considered more relevant for humans.

  • Fiberglass insulation mold: occurrence of mold contamination in fiberglass insulation can be impossible to see with the naked eye, but can be significant

Don't confuse fiberglass insulation with asbestos insulation

Fiberglass insulation is not and should not be confused with asbestos nor with the well-studied health hazards associated with exposure to asbestos fibers or dust.

Information about possible hazards of fiberglass insulation

For more details about the inspection and detection of concerns with fiberglass building insulation, see:
INSULATION INSPECTION & IMPROVEMENT and  FIBERGLASS HAZARDS .

Our separate websites on Fiberglass building insulation and or series of articles about HVAC duct work defects contain in-depth discussion about possible air quality and health concerns which may be associated with exposure to fiberglass dust.To compare insulating material R-values of fiberglass in various forms as well as other insulating materials, see our Table of Properties of Insulating Materials

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ASBESTOS IDENTIFICATION IN BUILDINGS
FIBERGLASS HAZARDS
  Recognizing Fiberglass Insulation
  Recognizing Fiberglass Duct Insulation
  Lab Identification of Fiberglass
  Fiberglass Fragment Hazards
  Fiberglass Detection in Building Air
  Mold in Fiberglass Insulation
  Actual mold growth in insulation
  Moldy insulation may look clean
  Why does mold grow in fiberglass?
  When to test insulation for mold
  Fiberglass Hazard References
INSULATION INSPECTION & IMPROVEMENT
  Asbestos Pipe Insulation
  Paper Duct Insulation
  URETHANE FOAM Deterioration, Outgassing
  Vermiculite Insulation
Asbestos-Free Insulation Materials
  Cotton Insulating Batts
  Cellulose loose fill insulation
  Concrete insulation, light-weight
  Fiberglass Insulation
  Foam Board Insulation
  Foam Insulation Types - Visual Id
  Homasote & Other Insulating Board
  Icynene Foam Spray Insulation
  Insects & Foam Insulation
  Mineral Wool - Rock Wool Insulation
  Mold in Fiberglass Insulation
  Mold in Foam Insulation
  Perlite Insulation

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

  • 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.
  • ...
ASBESTOS IDENTIFICATION IN BUILDINGS
FIBERGLASS HAZARDS
  Recognizing Fiberglass Insulation
  Recognizing Fiberglass Duct Insulation
  Lab Identification of Fiberglass
  Fiberglass Fragment Hazards
  Fiberglass Detection in Building Air
  Mold in Fiberglass Insulation
  Actual mold growth in insulation
  Moldy insulation may look clean
  Why does mold grow in fiberglass?
  When to test insulation for mold
  Fiberglass Hazard References
INSULATION INSPECTION & IMPROVEMENT
  Asbestos Pipe Insulation
  Paper Duct Insulation
  URETHANE FOAM Deterioration, Outgassing
  Vermiculite Insulation
Asbestos-Free Insulation Materials
  Cotton Insulating Batts
  Cellulose loose fill insulation
  Concrete insulation, light-weight
  Fiberglass Insulation
  Foam Board Insulation
  Foam Insulation Types - Visual Id
  Homasote & Other Insulating Board
  Icynene Foam Spray Insulation
  Insects & Foam Insulation
  Mineral Wool - Rock Wool Insulation
  Mold in Fiberglass Insulation
  Mold in Foam Insulation
  Perlite Insulation
  POLYISOCYANURATE FOAM INSULATION
  POLYSTYRENE FOAM INSULATION
  RADIANT BARRIERS
  RIGID FOAM USE INDOORS
More Information

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Contact Us

More Information on Building Diagnostic Inspections and Repairs

  • Asbestos: How to find and recognize asbestos in Buildings - visual inspection methods, list of common asbestos-containing materials
  • Asbestos HVAC Ducts and Flues field identification photos and guide
  • Fiberglass: Indoor Air Quality Investigations: Health Concerns About Airborne Fiberglass: Fiberglass in Indoor Air from HVAC ducts, and Building Insulation
  • Enviro-Scare: Electric Power Lines, Electromagnetic Fields, Cancer Risk, & "Enviro-Scare" - The Normal Curve Cycle of Public Fear of Environmental Issues
  • Dust from the World Trade Center collapse following the 9/11/01 attack: the lower floors of this building contained spray-on fire-proofing asbestos materials.
  • Asbestos Information Links: Asbestos Detection, Testing, Recognition, Hazards, Field Photos, and Information Sources, including health-related links such as legal services and information about mesothelioma and other cancers.
  • Asbestos Identification and Testing References
    • Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed the basis for current work by asbestos identification laboratories.
    • Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
    • Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone
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