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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.

Also see Micro-Photographs of Dust from the World Trade Center collapse following the 9/11/01 attack. Links to U.S. government and other authoritative research and advice are included.

© 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.

ASBESTOS-FREE MATERIALS - Examples of materials that do not commonly contain asbestos but might be mistaken for asbestos-containing substances

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.
 
  Cotton Insulating Batts
  Cellulose loose fill insulation
  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
  Radiant Barriers
  

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.

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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Use links just below or 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.

ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
IDENTIFICATION of ASBESTOS in BUILDINGS
Asbestos Risk Assessment
INSULATION INSPECTION & IMPROVEMENT
INSULATION IDENTIFICATION GUIDE
Mold Growth Resistance of Foam Insulation
Asbestos-Free Insulation Materials
  Asbestos Pipe Insulation
  Balsam Wool Batt Insulation
  Cotton Insulating Batts
  Cellulose loose fill insulation
  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
  Radiant Barriers
  Urea Formaldehyde Foam Insulation UFFI
  Vermiculite Insulation
INSULATION R-Values & Properties
Insulation Values of Log Home Walls
LIST of Asbestos Containing Products

• 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

Solid Foam Product Insulating Products - Rigid Polystyrene, Polyurethane, Polyisocyanurate Insulation Characteristics

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.

See Foam Board Insulation for details about solid foam board insulating products.

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.

[ASHRAE Fundamentals Handbook.]

To compare insulating material R-values see our Table of Properties of Insulating Materials

Also see Mold Growth Resistance of Foam Insulation, and see INSULATION INSPECTION & IMPROVEMENT for details about foam and other building insulation types; see FIBERGLASS HAZARDS for a discussion of mold problems in fiberglass insulation; see Mold On Foam Insulation for a discussion of when and why we find mold growth on foam insulating materials like foam board and air handler foam insulating board.

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 in Foam Insulation for details about the mold resistance of foam insulation.

Do we find Mold in Spray Icynene Foam Building Insulation in Buildings?

Some mold-suspect material in buildings is easily determined to be spray foam insulation.

Sprayed icynene foam insulation is not mold either. See  Icynene Foam Spray Insulation for details about Icynene insulation and how it is identified and see Mold in Foam Insulation for the mold resistance of these products.

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.

See INSULATION INSPECTION & IMPROVEMENT for details about foam and other building insulation types; see FIBERGLASS HAZARDS for a discussion of mold problems in fiberglass insulation;

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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