Asbestos Insulation

Asbestos Insulation

Years Produced: 1866 – 1978

Asbestos insulation was the biggest source of asbestos exposure for workers throughout the 1900s. It was used in homes, buildings, ships, cars and manufacturing facilities, just to name a few. If insulation was needed, asbestos was used. For much of the 20th century, insulators were referred to as “asbestos workers” because they handled the material so frequently.


At A Glance

  • Places Used: Attics, ceilings, walls, and basements in residential and commercial construction, as well as around pipes, boilers, furnaces and electrical boxes
  • Toxicity: High
  • Asbestos Use Banned: Yes
  • Friable: Yes

Insulation helps conserve energy, lower sound volume, reduce electrical conductivity, and retain hot and cold temperatures. Asbestos, a fire-resistant mineral that was cheap, durable and a poor conductor of electricity, naturally became a key ingredient of these products.

Some of the first uses of asbestos insulation occurred in the latter half of the 1800s where hot-temperature pipes were a concern. Heat insulation containing asbestos was used for the first time in 1866. A few years later in 1870, the mineral was mixed with cement for boiler coverings. By 1874, asbestos insulation products reached commercial production and were sold on a mass scale.

Bans on this type of insulation didn’t occur until the 1970s. In 1991, the U.S. Environmental Protection Agency (EPA) lifted the ban and made it possible for companies to produce these products as long as they contained less than 1 percent asbestos.

One of the biggest manufacturers of these insulation products was Johns Manville. It was also one of the first companies to publicly advertise that asbestos was a beneficial addition to their products during the early 1900s. From the early 1900s to the 1970s, Johns Manville made significant use of the mineral in a variety of its products.

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Other asbestos insulation manufacturers in the U.S. were:

  • A. P. Green Industries
  • A C & S
  • Armstrong World Industries
  • Celotex
  • C. E. Thurston & Sons
  • Certainteed Corporation
  • Combustion Engineering
  • Crown Cork and Seal
  • EaglePicher
  • GAF Corporation
  • Kaiser Aluminum
  • Ehret Magnesia
  • National Gypsum Company
  • Nicolet/Keasbey & Mattison
  • Owens Corning
  • Owens-Illinois
  • Pacor Incorporated
  • Rock Wool Manufacturing
  • Shook & Fletcher
  • The Flintkote Company
  • Unarco
  • Western MacArthur
  • W.R. Grace & Company

Types of Insulation

Insulation can be grouped into five main categories: attic, pipe, block, wall and spray-applied. Asbestos was incorporated into all of these types before regulations limited its use in products during the late 1970s.


Attic insulation was one of the primary sources for exposure. Zonolite insulation is one of the most recognized asbestos insulation brands and it was primarily used in attics. Heating, ventilation and air conditioning systems located in attics were often insulated using the mineral. Loose-fill attic insulation presented some of the greatest risks for exposure.


Pipe insulation or pipe covering remains one of the most hazardous asbestos products found in homes and buildings. It was often used to control the temperature of hot pipes, especially in shipbuilding. Pipe covering that is found today is usually old, crumbly and therefore very hazardous. Air Cell pipe insulation was a very common type.


Block insulation was applied to concrete blocks of homes, apartments and other buildings as a way to maintain hot and cold temperatures. It was an easy way to provide additional protection from the weather outside.


Wall insulation is the most important form for controlling the temperature inside a home or building. It was inserted directly behind drywall between the studs. This type usually came in a roll and sometimes required cutting so it could fit, increasing the risk for asbestos exposure.


Spray-applied insulation is a simple, inexpensive way to provide thermal protection in attics, walls, ceilings and other spaces. Unfortunately asbestos was a common additive in these products before regulations limited its use. In 1990, NESHAP prohibited the spray-on application of materials containing more than 1 percent asbestos unless it was encapsulated with a bituminous or resinous binder during spraying.

Valve Insulation Jackets

This product was used for boilers, flanges, pipe work, expansion joints and other temperature-sensitive equipment. They were typically used in industrial or commercial settings, although the energy efficiency they provided made them a useful tool in residential and public facilities, too. In good condition the jackets posed little risk. But as the jackets wore down through everyday wear and tear, asbestos fibers became airborne. Valve insulation jackets with asbestos are no longer made, but the dangers still exist in older buildings where they remain.

Other less common types of asbestos insulation included:

  • Cement
  • Blankets
  • Cloth
  • Paper products
  • Plasters


Many of these products were made of about 15 percent asbestos. This hazardous amount placed thousands, if not millions of workers at risk for inhaling toxic amounts of the fibers throughout much of the 20th century. Many have since developed related diseases like lung cancer, asbestosis and mesothelioma.

Some occupations at risk for coming into contact with asbestos insulation include:

Manufacturers of this insulation were especially at risk for inhaling asbestos while on the job. These employees worked directly with the mineral, and their work environment often bore higher-than-normal airborne asbestos levels.


Because product manufacturers knowingly incorporated asbestos into their products after learning it was hazardous, thousands have filed suit against the manufacturers as a result of developing an related disease. In Rivera v. Owens Corning Fiberglass Corporation, a verdict of nearly $3.5 million was awarded to the estate of Jesse Rivera, who passed away from mesothelioma cancer. Rivera worked for Owens Corning and was exposed to their Kaylo insulation product from 1963 to 1966.

In another case, a Philadelphia Court of Common Pleas jury awarded $400,000 to the estate of Albert Batten Sr. in September 2008 because he was diagnosed with lung cancer after working 40 years at an Owens Corning plant. During his employment he worked with valve and pipe insulation. Batten smoked a pack of cigarettes a day for 50 years, but the expert pathologist linked his cancer to the asbestos in the products at Owens Corning.

A jury in the same court awarded $6 million in May 2009 to Dean Busatto and his wife after he was diagnosed with mesothelioma. Busatto was a machinist mate in the U.S. Navy from 1956 to 1959, where he worked with asbestos-containing thermal insulation used in jackets made by Melrath Gasket Inc.


Some brands of asbestos-containing insulation include:

  • Air Cell
  • Zonolite
  • Gold Bond
  • HiTemp
  • Kaylo
  • Limpet
  • Marinite
  • Monokote
  • Superex
  • Super 66
  • Unibestos
  • Silicate Catsilite
  • Careytemp
  • Hy-Temp
  • Thermobestos

Zonolite Insulation

One of the biggest manufacturers of asbestos insulation was W.R. Grace & Company, producer of Zonolite insulation. This particular product used naturally occurring vermiculite from a mine in Libby, Montana as a form of insulation. Unfortunately the mine also contained asbestos. It’s documented that Zonolite was used in millions of homes as attic insulation and that the Libby mine was the source of more than 70 percent of all vermiculite sold in the United States between 1919 and 1990. An estimated 30 million homes may still have Zonolite in attics, according to the EPA.

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Matt Mauney is an award-winning journalist with nearly a decade of professional writing experience. Prior to joining The Mesothelioma Center as a Content Writer in 2016, Matt spent three years as an Online Producer for the Orlando Sentinel.

  1. Dodson, R. and Hammar, S. (2011). Asbestos: Risk Assessment, Epidemiology, and Health Effects. Boca Raton: Taylor & Francis.
  2. Environmental Protection Agency. (1999, May 18). EPA Asbestos Materials Bans: Clarification. Retrieved from
  3. Environmental Protection Agency. (2012, July 10). Vermiculite. Retrieved from
  4. Asbestos Books. Heating and Insulation. Retrieved from
  5. Environmental Protection Agency. (2012, June 7). Current Best Practices for Vermiculite Attic Insulation. Retrieved from

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