For centuries, asbestos was considered a magic material. This fibrous silicate mineral is abundant, it won’t burn, and it’s unaffected by corrosive chemicals.

In ancient times, the Greeks spun it into cloth and the Romans used it to make candle wicks. Because the fibers are strong and add reinforcement, potters incorporated it into clay goods. When large deposits were discovered in parts of Canada and the Northern U.S. in the 1800s, manufacturers used it for construction materials, including insulation.

But in the 20th century, asbestos was recognized as a health hazard. Since then, it’s been mostly banned. Houses built prior to the 1980s may still contain asbestos insulation in walls and attics, around pipes and in other places.

“Asbestos-containing insulation cannot be identified visually,” says Michelle Whitmer, an asbestos expert with The Mesothelioma Center. “Homeowners should hire professionals to test suspicious materials instead of using DIY testing kits.”

But Reuben Saltzman, CEO of Structure Tech, disagrees. He says the most common materials with asbestos — vermiculite loose-fill and pipe insulation — aren’t that difficult to identify.

When Was Asbestos Insulation Banned?

Researchers linked asbestos to disease in the early 1900s. Efforts by the U.S. government to regulate its use began in the 1930s, despite opposition by various manufacturers. Congress passed laws in the 1970s that empowered federal agencies to impose restrictions.

Acting under the auspices of one such law, the Occupational Safety and Health Administration (OSHA) declared asbestos to be carcinogenic in 1975.

Similarly, after passage of the Toxic Substances Control Act of 1976, the Environmental Protection Agency (EPA) made efforts to ban asbestos from building materials. While neither constituted an outright ban, they marked the beginning of the end for asbestos insulation.

Asbestos use continued into the 1980s, however, until the EPA issued a ban and phase-out rule in 1989 to prohibit the manufacture, importation, processing and sale of asbestos-containing products. The U.S. Court of Appeals for the Fifth Circuit overturned the rule in 1991, however. as a result, asbestos continues to be allowed in certain products, like automobile brake linings and gaskets.

New legislation increased the EPA’s authority, and it issued a final rule in 2019 banning asbestos in new construction materials.

What Does Asbestos Insulation Look Like?

“Asbestos insulation may look like wrapping material or loose-fill material that is fluffy or stony in appearance,” says Whitmer.

“The types of insulation in homes most likely to contain asbestos include loose-fill vermiculite insulation and wrap insulation commonly found around pipes and A/C units. Some homes may have spray-on or block insulation containing asbestos, but these materials were most common in commercial buildings.”

Asbestos pipe insulation

Asbestos pipe insulation is often white and may be taped in place, says Whitmer. She notes many types of wrap insulation don’t contain asbestos, so this material needs testing the most.

Adds Saltzman: “If you look at a cross-section of the pipe, it’s going to look like cardboard. When you see that, it’s almost a guarantee that it contains asbestos.”

Fibrous loose-fill insulation

Your chances of coming across fibrous loose-fill insulation containing asbestos is slim, according to Saltzman. However, Whitmer says small amounts of loose-fill containing asbestos fibers may still be out there. “Some loose-fill asbestos insulation appears whitish or gray and fluffy,” she says.

Fiberglass, on the other hand, is usually yellow or pink, while cellulose looks like little pieces of paper.

Whitmer adds whitish insulation is mainly composed of amphibole asbestos varieties like chrysotile and tremolite, which can also appear greenish. The grayish loose-fill contains crocidolite, a serpentine asbestos with a bluish tinge. Other types of asbestos that may be in loose-fill, like amosite and anthophyllite, may turn it brown.

Vermiculite

“The one big type of insulation that contains asbestos is vermiculite,” says Saltzman. He describes it as light, fluffy stuff that looks like little rocks but weighs about as much as Styrofoam. Vermiculite derived from a mine in Libby, Montana and marketed under the brand name Zonolite is the main offender.

If you find this in your walls or attic, says Saltzman don’t just send it to a lab for testing, because the asbestos content is below the EPA’s threshold level of one percent. “This particular material is still very, very dangerous,” he says.

The best course of action? Contact the Zonolite Attic Insulation Trust for a test kit. And after you collect a sample and mail it back, they’ll determine whether it came from the Libby mine. “My advice is to treat is like it does contain asbestos until proven otherwise,” he says.

Asbestos block insulation

Block insulation isn’t actual blocks, but rather rectangular batts, or panels, from one to four inches thick. They’re usually made from a combination of foam, fiberglass and asbestos. The asbestos is often visible as small, hairlike fibers extending from the surface.

Asbestos foam insulation

Asbestos spray foam, often found in basements of older homes, resembles polyurethane foam, except it’s gray instead of yellowish with a bumpy, fibrous texture. If it’s in good condition, Saltzman recommends leaving it alone. If some of it has frayed, encapsulate it with an elastomeric or plastic coating.

How To Tell the Difference Between Cellulose and Asbestos Insulation

After 1976, cellulose became the most common substitute for loose-fill asbestos. In some really old homes, the two might be mixed together in wall or attic cavities.

Cellulose isn’t fibrous like asbestos. “If it looks like fiberglass or cellulose, it will not contain asbestos,” Saltzman says.

The best way to distinguish one from the other is by color. Cellulose is typically a pastel white, yellow or gray. Asbestos loose-fill may be also white or gray, but it often has tinges of blue, brown or black.

What To Do if You Find Asbestos Insulation

If you suspect the presence of asbestos insulation, get it tested ASAP. You can buy kits that let you collect a sample and send it to a lab. Or, if you follow Whitmer’s advice, have pros come into your home to do the testing. That’s probably safer, although considerably more expensive.

Kits cost from $10 to $35 with postage included. The cost for an in-home evaluation runs from $200 and $800, depending on the size of the home and how much asbestos may be present.

If the insulation tests positive for asbestos, you don’t necessarily need to remove it. If it’s in a sealed cavity, or locked into a solid form so the fibers can’t become airborne, it’s safe to leave it in place.

However, when you’re remodeling, disturbing the insulation and filling the air with asbestos fibers is unavoidable. In that case, you should test it and remove it.

No federal law prohibits you from removing asbestos insulation yourself, but some state regulations do. The task is extremely dangerous because microscopic fibers that you inhale can settle in your lungs and cause a serious form of cancer called mesothelioma.

No matter where you live, it’s best to call an asbestos abatement company and have the insulation professionally removed.

About the Experts

• Michelle Whitmer is a writer and asbestos expert at The Mesothelioma Center at Asbestos.com. She has more than 14 years of experience covering medical and environmental issues.
• Reuben Saltzman is CEO of the Minnesota-based home inspection service Structure Tech. He teaches home inspection seminars across the country.