Basic Properties of Fiberglass Building Insulation

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
FIBERGLASS DUCT, RIGID CONSTRUCTION - separate article
FIBERGLASS ENVIRO-SCARE - separate article
FIBERGLASS HAZARDS - separate article
FIBERGLASS HVAC DUCTS - separate article
FIBERGLASS INSULATION IDENTIFICATION
FIBERGLASS INSULATION MOLD - separate article
FIBERGLASS PARTICLE CONTAMINATION TEST - separate article
Questions & Answers about how to identify fiberglass building insulation products & brands & how to distinguish fiberglass from other insulating material both by visual inspection and by forensic lab tests
References

Click to Show or Hide Related Topics

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Fiberglass insulation products & brands: identification photos. This article illustrates and describes common fiberglass insulation materials used in buildings and in building HVAC systems. We provide fiberglass photographs and identification examples because of frequent questions about how to recognize fiberglass building insulation products. This document assists building buyers, owners or inspectors who need to identify asbestos materials (or probable-asbestos) in buildings by simple visual inspection.

We include 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. Also see FIBERGLASS HAZARDS.

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

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.

Black 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

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

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

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

Frequently Asked Questions (FAQs)

...

Ask a Question or Search InspectApedia

Questions & answers or comments about how to identify fiberglass building insulation products & brands & how to distinguish fiberglass from other insulating material both by visual inspection and by forensic lab tests.

Ask a Question or Enter Search Terms in the InspectApedia search box just below.

Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

3/07: thanks to Gary Randolph, Ounce of Prevention Home Inspection, LLC Buffalo, NY, for attentive reading and editing suggestions. Mr. Randolph can be reached in Buffalo, NY, at (716) 636-3865 or email: gary@ouncehome.com
06/07: thanks for photographs of transite asbestos heating ducts, courtesy of Thomas Hauswirth, Managing Member of Beacon Fine Home Inspections, LLC and (in 2007) Vice President, Connecticut Association of Home Inspectors Ph. 860-526-3355 Fax 860-526-2942 beaconinspections@sbcglobal.net