Insulating Material Identification Guide
How to Identify All Types of Building
Insulation Products InspectAPedia® -
Photo guide to identification of different building insulation materials
Properties of different building insulation products
Description of non-asbestos materials sometimes mistaken for asbestos in buildings
Types & photographs of building insulation that does not normally contain asbestos
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This page includes links to articles identifying each type of building insulation, and it illustrates and describes common insulation materials that would not be expected to contain asbestos. 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 asbestos insulation and other asbestos-containing products
to permit identification of definite, probable, or possible asbestos materials in buildings.
While an expert lab test using polarized light microscopy may be needed to identify the specific type of
asbestos fiber, or to identify the presence of asbestos in air or dust samples, many asbestos-containing building products
not only are obvious and easy to recognize, but since there were not other look-alike products that were not asbestos, a visual identification of this material can be virtually a certainty in many cases.
Also see Asbestos HVAC Ducts a field identification guide to
visual detection of asbestos in and on heating and cooling system ducts and flue vents.
ASBESTOS-FREE INSULATION MATERIALS vs ASBESTOS-CONTAINING INSULATION - Examples of insulating materials that do or do not commonly contain asbestos including some mistake for asbestos
Our photo at left is of blown-in cellulose insulation. The links just below under the green heading provide articles describing building insulation materials that would not be expected to contain asbestos.
These non-asbestos insulations include cellulosic insulations such as loose-fill cellulose and balsam wool batts, cotton insulation, fiberglass insulation, mineral wool insulation, slag wool insulation, and rock wool insulation.
Our photograph (left) shows indoor use of polystyrene foam insulating board on the inside of a basement foundation wall - notice the absence of a suitable fire-resistant covering? This installation probably violates local building codes. Foam insulating boards do not contain asbestos but can present a fire hazard because they give off dense smoke and possibly toxic fumes in a fire.
Other older building insulation materials such as corn cobs, newspaper, bricks, and simple reflective barriers using aluminum foil also would not be expected to contain asbestos.
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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
Solid Foam Product Insulating Products - Rigid Polystyrene, Polyurethane, Polyisocyanurate Insulation products will not contain asbestos fibers and most of these products are rather mold resistant, possibly because of their chemistry or because closed-cell foam insulations simply do no take up and hold the moisture that is required for active mold growth on or in building insulations or surfaces.
What are the Insulation R-Values of Foam Insulation Boards?
Expanded, extruded, and cut bead polystyrene insulation products have an R-value of about 4.0 per inch of thickness. Typical exterior foam board building insulation sheets have an R-value of 2.64 per inch.
Expanded polyurethane building insulation products have an R-value of about 5.0 per inch of thickness.
Expanded polyurethane insulation expanded using the refrigerant gas has an R-value of about 6.25 per inch.
Polyisocyanurate insulation products have an R-value of about 7.04 per inch.
Mold on Foam Insulation: Explanation & Assessment of the Growth of Mold on Solid Foam Insulation Products
However we have observed surface mold growth on polystyrene foam board insulation. In those instances where we found mold on foam rigid insulating boards it has sometimes been due to the combination of exposure to wet conditions and the presence of organic dust and debris on the surface of the foam.
We've seen these mold-friendly conditions producing mold on foam insulation materials (and on even less mold-friendly materials like metal or glass or un-painted masonry block foundation walls) where the insulation surface was wet, kept in a wet or very humid environment, and was dusty or dirty. This is a probable explanation for the frequent discovery of mold in building air conditioning air handlers or blower compartments. In air handlers condensate over spray is often blown around in the blower compartment.
There are mold species that can grow on just about anything; but the presence of hair, skin cells, and other organic debris on building surfaces may explain why we find more mold growth on foam board insulation in one location and no mold growth on the same building product used somewhere else.
Usually the mold we identify in building air handlers is a species of Cladosporium sp. - called the "king of molds" because molds in this family are so widespread outdoors. Cladosporium sp. is not without its own health concerns for some building occupants, but when this mold is found indoors it may be more important to determine why it is there and therefore to determine the chances that other, more toxic and more easily airborne mold genera/species are present in the same building.
See Mold On Foam Insulating Boards for a discussion of when and why we find do mold growth on foam insulating materials like foam board and air handler foam insulating board.
A few folks have seen this yellow material in a crawl space and feared that it was a mold infection. Though we sometimes find fungal growth in buildings that looks a lot like this substance, it would be very odd for it to appear so extensively and so uniformly as the foam insulation shown in this photo. This is a sprayed-on icynene foam insulation project that was completed in a crawlspace. Because the work area was tight, it was difficult for the foam spraying technician to work meticulously but s/he did a pretty nice job.
Using a combination of visual inspection and smoke testing we found only two openings in the foam blanket that were permitting air movement from the crawl space up into the living space. Overall it was an effective installation.
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: How to find and recognize asbestos in Buildings - visual inspection methods, list of common asbestos-containing materials
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 McCron3
Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Wiley.com and also at Amazon.com. See our book review of this publication.
More Information on Building Diagnostic Inspections and Repairs
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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
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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