How to Identify Dangerous Asbestos Insulation

Attic Insulation

Gary Ombler / Getty Images 

Asbestos hardly needs an introduction anymore as most homeowners should be schooled in the general dangers of disturbing and breathing asbestos fibers. In older homes, specifically, asbestos may be found in many different materials, from pipe insulation to flooring adhesive to roof shingles. One of the most common materials containing asbestos fibers is attic and wall insulation. But just because your insulation is old doesn't mean it is dangerous. A quick visual inspection can tell you whether or not you should get your insulation tested for asbestos.

Loose-Fill Insulation

If your attic or wall insulation is in batt or blanket form, whether it's fiberglass, cellulose, or another material, you generally don't have to be concerned about asbestos. The types of insulation that were most commonly made with asbestos are loose-fill, also called blown-in, insulation. Loose-fill insulation comes in a variety of materials. It is easy to identify by its loose, lumpy form and fluffy or granular texture. Loose-fill never has paper or other types of backing, like some (but not all) batt and blanket insulation does.

If you determine that your attic or walls have loose-fill insulation, the next step is to determine what type of material it is, as only some types may contain asbestos.

Vermiculite Insulation

Vermiculite loose-fill insulation is one of the most common household materials that contains asbestos. Vermiculite insulation has a pebble-like appearance and typically is a grayish-brown or silvery-gold color. It is made from a natural mineral material that is mined from the earth. The mineral expands when heated, creating the lightweight and somewhat stony-looking particles that make up the insulation.

In the United States, most of the vermiculite insulation containing asbestos was sourced from a mine near Libby, Montana, which was active until 1990. The raw vermiculite material taken from the mine was contaminated with asbestos. Insulation made from this material represents over 70 percent of the vermiculite insulation found in U.S. homes.

Because the Libby mine closed in 1990, houses built or remodeled before that date might have asbestos-containing insulation. If the house was built after 1990, the chances of have asbestos-contaminated insulation are reduced but not eliminated.

Beware All Vermiculite Insulation

If you have vermiculite insulation in your home, you should treat it as though it contains asbestos unless you can confirm through testing that it is safe.

Cellulose Insulation

If you have loose-fill insulation that is gray, soft, and without a shine, it is probably cellulose insulation. Cellulose contains a high percentage of recycled paper and does not contain minerals. In general, it looks like shredded gray paper. Cellulose insulation is a perfectly safe type of insulation that is commonly blown into attics. It also comes in batt and blanket forms.

Loose-Fill Fiberglass

If you have loose-fill insulation that is white and fluffy and has a little shine, it is probably fiberglass fill. Because it is a glass product, fiberglass has a slight shine when subjected to bright light. It is very soft, almost like cotton candy, and is composed on very fine fibers. Fiberglass can irritate the skin and potentially cause respiratory irritation, but it is not known to cause cancer or other significant health problems.

Rock Wool Insulation

Another mineral-based loose-fill insulation is rock wool, which has a fibrous, soft, cottony texture. Rock wool is usually gray, white, off-white, or brownish-white. It is a manufactured product, made by melting basaltic rock and dolomite with added binders. The raw material is heated to 2,750 degrees Fahrenheit until it melts, then the molten material is spun into fibers with air pressure. Rock wool is installed as loose insulation or as woven insulation batts. Like fiberglass, it should be handled with care, but it is not known to contain asbestos or pose any serious health risks. 

illustration of attic insulation types
The Spruce / Elnora Turner 

What to Do With Suspicious Insulation

If your loose-fill insulation fits the visual cues for vermiculite, the first thing to do is to avoid disturbing it. Asbestos fibers are most dangerous when they are airborne and can be breathed in. Leaving insulation undisturbed greatly reduces the risk of exposure.

You can test the insulation for asbestos using a DIY asbestos testing kit or by having a sample tested at an approved testing laboratory. If you discover that you do have insulation containing asbestos, you can leave it in place or have it removed by a local asbestos abatement company. For more information on dealing with vermiculite insulation, visit the website of the U.S. Environmental Protection Agency (EPA).