Chopped fiberglass insulation in a modern atticProperties of Fiberglass Building Insulation

  • POST a QUESTION or READ FAQs 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

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 article series 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.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

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 show the colors (and manufacturers) 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, as we illustrate later in this article. 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 this PHOTO of FIBERGLASS in the MICROSCOPE below in this article shows yellow resin binder.

Thermal bypass stains on fiberglass insulation

Above: the black colored fiberglass is actually from staining.

White fiberglass batt

Above: In our photo below you can see the very beginnings of such staining in the right-side center of a white fiberglass batt. If you see dirty or black marks on fiberglass it's probably a thermal bypass leak.>

Below: blue fiberglass.

Blue fiberglass insulation (C) Blue fiberglass insulation (C)

Knauf brown Ecose insulation at

photo of balsam wool building insulation

photo of balsam wool building insulation

Watch out: insulation colors and product descriptions can be confusing.

Owens Corning also produced yellow-colored fiberglass as well as products sold as "insulating wool" or "glass wool", possibly in an effort to compete with "rock wool" or mineral wool insulation that were advertised as "natural products".

Below we illustrate Armstrong "natural fiber" Insulating Wool, actually a yellow fiberglass insulation product labelled as actually produced by Owens Corning Fiberglass corporation.

Armstrong insulating wool (C) Armstrong insulating wool (C)

[Click to enlarge any image]

Armstrong insulating wool (C) Armstrong insulating wool (C)


Below: white fiberglass insulation.

photo of balsam wool building insulation

photo of balsam wool building insulation


Insulating Characteristics of Fiberglass Insulating Batts & Chopped Fiberglass Insulation

Fiberglass building insulation typically has an "R" value of 3.14 per inch. Shown above, a white fiberglass insulation batt.

Shown below, pink chopped fiberglass insulation installed as a loose-fill or more-likely blown-in fiberglass insulation product.

Chopped fiberglass insulation in a modern attic

[Click to enlarge any image]

Does Fiberglass Insulation Contain Asbestos?


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.

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:

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 website articles on FIBERGLASS BUILDING INSULATION HAZARDS 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


Continue reading at FIBERGLASS HAZARDS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see INSULATION IDENTIFICATION GUIDE for all types of building insulation materials

Or see these

Special Fiberglass Insulation Topics

Suggested citation for this web page

FIBERGLASS INSULATION IDENTIFICATION at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

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.

Search the InspectApedia website

HTML Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman