Mineral wool insulation in an atticHow to Identify Building Insulation Products Not Likely to Contain Asbestos

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

Guide to asbestos-free building insulation products: this non-asbestos insulation article illustrates and describes common insulation materials that would not be expected to contain asbestos. We include photographs that can help you identify common building materials that are unlikely to have ever contained asbestos.

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.

Asbestos-Free Insulation Materials: Examples of materials that do not commonly contain asbestos but might be mistaken for asbestos-containing substances

cellulose building insulation

Our photo at above 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.

Our page top photo shows mineral wool insulation in a building attic - mineral wool or "rock wool" is not expected to be an asbestos-containing material.

To identify all types of building insulation, see INSULATION IDENTIFICATION GUIDE or the detailedlinks listed at the ARTICLE INDEX the bottom of this article .

photo of balsam wool building insulation

Balsam wool is a wood or cellulose product discussed in detail at Balsam Wool Batt Insulation. See that article for more about asbestos questions concerning this wood product material.

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.

Also see ASBESTOS IDENTIFICATION IN BUILDINGS That article describes, lists, and provide identification photos of building materials that are likely to contain asbestos.

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

solid foam insulating  boardSolid 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.[ASHRAE Fundamentals Handbook.]

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

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.


Also 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.

Spray Icynene Foam Building Insulation Identification in buildings

Foam insulation sprayed in a crawl space - this is not mold - Daniel Friedman 04-11-01Some mold-suspect material in buildings is easily determined to be spray foam insulation.

Sprayed icynene foam insulation is not mold either.

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.

In the ARTICLE INDEX given below we include more articles helpful if you need to identify


Continue reading at INSULATION IDENTIFICATION GUIDE - home, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Suggested citation for this web page

ASBESTOS-FREE INSULATION MATERIALS 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


Ask a Question or Search InspectApedia

Questions & answers or comments about finding, using, diagnosing, repairing, or replacing water pressure gauges on private well systems.

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 - Daniel Friedman