Asbestos was used in dozens of construction products from the early 1900s through the late 1970s, and in some cases into the 1990s. Its natural resistance to heat, fire, chemicals, and biological breakdown made it one of the most versatile building materials of the 20th century. It also offered tensile strength, sound insulation, electrical insulation, and exceptional wear resistance, which is why manufacturers mixed it into everything from roof shingles to floor tile adhesive.
Insulation for Pipes, Boilers, and Attics
Insulation was the single biggest use of asbestos in construction. Steam pipes and hot water pipes in older buildings were wrapped in asbestos blankets or asbestos paper tape to prevent heat loss and reduce fire risk. Boilers, furnaces, and hot water tanks were covered with pre-formed asbestos block insulation or molded insulation that fit snugly around curved surfaces. Furnace ducts were similarly insulated, and the door gaskets on furnaces, wood stoves, and coal stoves contained asbestos to create heat-resistant seals.
Attic and wall insulation is another major source. Vermiculite, a naturally occurring mineral that expands dramatically when heated, was widely sold as loose-fill, pour-in attic insulation. Over 70 percent of all vermiculite sold in the United States from 1919 to 1990 came from a mine near Libby, Montana, where a natural asbestos deposit contaminated the ore. That vermiculite was sold under the brand name Zonolite and ended up in millions of American homes. It looks like small, pebble-shaped granules, usually gray-brown or silver-gold.
Roofing, Siding, and Cement Products
Asbestos-cement products, commonly called transite, were a construction staple for decades. Manufacturers mixed asbestos fibers into Portland cement to create materials that were lightweight, fireproof, and extremely durable. The resulting products included corrugated and flat cement sheets, roofing shingles, and exterior siding panels. Transite siding and roofing remain common on older homes and commercial buildings across the country.
Beyond exterior surfaces, asbestos cement was also formed into pressure pipes, conduits, and ducts for water and sewer systems. Asbestos cement millboard and paper were used as heat shields around furnaces and wood-burning stoves, placed between the heat source and nearby walls or floors to prevent fires.
Flooring and Floor Adhesives
Vinyl asbestos floor tiles were one of the most common residential and commercial flooring products from the 1930s through the early 1980s. Asphalt floor tiles also contained asbestos. The backing on vinyl sheet flooring frequently did as well. If you have 9-inch by 9-inch floor tiles in an older home, there’s a reasonable chance they contain asbestos, since that size was standard during the peak years of asbestos use.
The adhesives used to install those tiles are a separate concern. Black mastic, a tar-like paste applied beneath floor tiles, was one of the most common asbestos-containing adhesives in construction. Asbestos content in adhesives ranged from 1 to 25 percent depending on the product. While not every brand contained asbestos, the mineral was a routine additive in flooring mastics, sealants, and cements well into the 1990s. This means that even if your floor tiles test negative for asbestos, the glue underneath them may not.
Walls, Ceilings, and Textured Coatings
Spray-on textured ceiling coatings, commonly known as “popcorn ceilings,” frequently contained asbestos before their use was banned in 1977. These coatings were popular because they dampened sound and hid imperfections in ceiling surfaces. Materials are generally considered asbestos-containing if lab testing finds more than one percent asbestos by weight.
Patching compounds and joint compounds (the mud used to finish drywall seams) also contained asbestos through the 1970s. Textured wall paints were another source. Soundproofing and decorative materials sprayed onto walls and ceilings in commercial and residential buildings rounded out the list of asbestos-containing wall products.
Adhesives, Sealants, and Tapes
Asbestos showed up in a surprisingly broad range of bonding products. Manufacturers mixed the fibers into mastics, sealants, joint fillers, and cements used throughout HVAC systems, plumbing, roofing, and general construction. Liquid construction mastics, conventional lime-type cements, and synthetic plastic cements all came in asbestos-containing versions. These products were used on walls, ceilings, roofs, boilers, furnaces, and machinery in homes, commercial buildings, and public structures.
Even duct tape commonly contained asbestos fibers before the mineral’s health risks were widely understood.
How to Tell If Your Home Has Asbestos
Houses built between 1930 and 1950 are particularly likely to contain asbestos insulation, but any home built before 1980 could have asbestos in multiple locations. The Consumer Product Safety Commission identifies these as the most common spots: pipe and boiler insulation, floor tiles and their adhesives, cement roofing and siding, textured ceilings and walls, furnace insulation and door gaskets, and drywall joint compounds.
You cannot identify asbestos by looking at it. Laboratory testing is the only way to confirm whether a material contains asbestos fibers. What you can do is watch for damage. Asbestos materials that are intact and undisturbed generally do not release fibers. The danger comes when materials are crumbling, torn, water-damaged, or have been sawed, scraped, or sanded into powder. If you suspect a material contains asbestos, do not touch it, sand it, or try to remove it yourself.
Current Regulations on Legacy Asbestos
The EPA banned spray-applied asbestos surfacing materials, asbestos pipe insulation, and asbestos block insulation under the Clean Air Act. A 1989 rule banned asbestos-containing corrugated paper, rollboard, commercial paper, specialty paper, flooring felt, and any new commercial uses of asbestos. In 2019, the EPA added a rule preventing discontinued asbestos products from returning to the market without review.
In March 2024, the EPA finalized a rule prohibiting all ongoing uses of chrysotile asbestos, the only form still being imported and processed in the United States. Later that year, the agency completed a supplemental risk evaluation covering legacy uses of asbestos, the materials already installed in existing buildings. The EPA determined that these legacy uses, including floor and ceiling tiles, pipe wraps, insulation, and heat-protective textiles, significantly contribute to unreasonable health risk. The agency is now developing risk management rules to address them.
None of this means that asbestos has disappeared from the built environment. Millions of older buildings still contain asbestos products that were perfectly legal when installed. The regulatory focus has shifted from banning new products to managing the vast amount of asbestos already in place.