Asbestos Cement Siding Shingles — National Gypsum Co.

Asbestos cement siding shingles manufactured by National Gypsum Co. were a widely used building product produced from 1953 through 1981. Workers involved in the manufacture, installation, cutting, and removal of these shingles faced documented risks of asbestos fiber exposure over a span of nearly three decades. Litigation records document that plaintiffs alleged serious injury resulting from occupational contact with these products, and legal proceedings against National Gypsum Co. have continued through the civil court system.

Product Description

Asbestos cement siding shingles were flat or textured panels designed to clad the exterior walls of residential, commercial, and industrial buildings. Marketed for their durability, fire resistance, and low maintenance requirements, these shingles were a competitive alternative to wood siding during the mid-twentieth century building boom. National Gypsum Co., one of the largest building materials manufacturers in the United States during this era, produced asbestos cement siding shingles as part of a broader portfolio of construction products.

The shingles were pressed into flat or slightly contoured forms and were installed in overlapping rows along exterior wall surfaces, resembling traditional wood clapboard or slate roofing. Their appeal to builders and property owners rested on claims of weather resistance and longevity. However, the incorporation of asbestos fibers into the cement matrix — the very property that contributed to their strength and fire resistance — also made these products a potential source of hazardous fiber release under certain conditions.

National Gypsum Co. produced these shingles continuously from 1953 until 1981, when regulatory pressure, evolving awareness of asbestos-related health risks, and shifting market conditions contributed to the decline and eventual cessation of asbestos-containing building product lines across the industry.

Asbestos Content

National Gypsum Co.’s asbestos cement siding shingles contained chrysotile asbestos, the most commonly used form of asbestos in manufactured building products throughout the twentieth century. Chrysotile, sometimes referred to as white asbestos, is a serpentine mineral fiber that was prized by manufacturers for its flexibility, tensile strength, and ability to bond with Portland cement and other binding agents.

In asbestos cement products, chrysotile fibers were thoroughly mixed with cement slurry during the manufacturing process. The resulting composite material was then formed under pressure into shingle panels and cured. The chrysotile content in such products typically served to reinforce the cement matrix and improve impact resistance, while also providing fire-retardant properties that were heavily promoted in marketing materials of the period.

Regulatory frameworks developed in subsequent decades recognized chrysotile asbestos as a human carcinogen. The Environmental Protection Agency’s Asbestos Hazard Emergency Response Act (AHERA), enacted in 1986, and Occupational Safety and Health Administration (OSHA) standards governing asbestos in the workplace both establish that chrysotile fibers can cause mesothelioma, lung cancer, and asbestosis when inhaled. These regulatory findings underpin the legal claims that have been brought against manufacturers of chrysotile-containing products, including National Gypsum Co.

How Workers Were Exposed

Workers across multiple stages of the product lifecycle faced potential asbestos fiber exposure from National Gypsum Co.’s asbestos cement siding shingles. Industrial workers employed at manufacturing facilities where these shingles were produced faced the most direct and sustained exposures. During the mixing, pressing, cutting, and finishing stages of production, raw chrysotile fibers and partially cured cement composites could release airborne fibers into the work environment.

Cutting and shaping operations were among the highest-risk tasks documented in industrial settings. Asbestos cement shingles required scoring and snapping, or in many cases sawing with power tools, to achieve the dimensions needed for installation. These processes — whether performed at a manufacturing facility or on a job site — could generate substantial quantities of airborne asbestos dust. In manufacturing environments, workers operating cutting equipment, trimming lines, and finishing machinery were routinely exposed to this dust in the absence of adequate engineering controls or respiratory protection during the decades of the product’s production.

Warehouse and shipping workers who handled packaged shingles, as well as quality control personnel who inspected finished products, also worked in proximity to asbestos-containing materials throughout the production years. Industrial workers in general trades who were present at National Gypsum Co. facilities — including maintenance workers, equipment operators, and laborers — could encounter asbestos fibers released incidentally from the manufacturing environment.

Exposure was not limited to acute, high-dust events. Chronic, low-level inhalation of chrysotile fibers over months and years of employment at manufacturing facilities represents the exposure pattern most closely associated with the development of asbestos-related disease. The latency period for diseases such as mesothelioma — the period between initial exposure and clinical diagnosis — can range from 20 to 50 years, meaning that workers exposed during the 1953–1981 production period may not have received diagnoses until well into the 1990s, 2000s, or more recently.

National Gypsum Co. does not have an active asbestos bankruptcy trust fund associated specifically with claims arising from this product. As a result, individuals seeking legal remedy for asbestos-related illness linked to these siding shingles must pursue their claims through civil litigation rather than through a trust fund claims process.

Litigation records document that plaintiffs have alleged injuries including mesothelioma, lung cancer, and asbestosis arising from occupational exposure to asbestos-containing products attributed to National Gypsum Co. and related corporate entities. Plaintiffs alleged that National Gypsum Co. knew or should have known about the hazardous properties of chrysotile asbestos during the production period and failed to adequately warn workers or the public about the associated health risks.

Civil litigation involving asbestos-containing products manufactured by National Gypsum Co. has been pursued in state and federal courts. Plaintiffs alleged negligence, failure to warn, strict products liability, and in some cases fraudulent concealment of known hazards. Litigation records document proceedings in multiple jurisdictions involving claimants who worked directly in National Gypsum Co. facilities or who otherwise encountered the company’s asbestos-containing building products.

Individuals who were employed as industrial workers at National Gypsum Co. manufacturing facilities between 1953 and 1981, or who worked in environments where these siding shingles were produced or processed, and who have received a diagnosis of mesothelioma, lung cancer, asbestosis, or another asbestos-related disease, may have legal grounds to pursue a civil claim. Because asbestos litigation involves complex product identification, medical causation, and statute of limitations questions, affected individuals and their families are advised to consult with an attorney experienced in asbestos disease litigation as early as possible following diagnosis.