G.B. Corrugated “400” Siding and Roofing Material

Product Description

G.B. Corrugated “400” Siding and Roofing Material was a corrugated sheet product manufactured under the National Gypsum Company’s product portfolio. National Gypsum, headquartered in Dallas, Texas, was one of the largest building materials manufacturers in the United States throughout much of the twentieth century, producing a wide range of construction and industrial products sold under several brand names, including the “G.B.” label.

Corrugated siding and roofing sheets of this type were widely used in industrial, agricultural, and commercial construction applications. Their corrugated profile provided structural rigidity with relatively thin material, making them practical for large-span roofing systems, exterior wall cladding on warehouses and manufacturing plants, and agricultural outbuildings. The “400” designation identified a specific product line or performance grade within National Gypsum’s corrugated sheet offerings. These materials were marketed as durable, weather-resistant solutions capable of withstanding harsh environmental conditions, which contributed to their appeal across a broad range of building projects throughout the mid-twentieth century.

Because corrugated fiber-cement and similar composite sheet products of this era commonly incorporated asbestos mineral fibers as a reinforcing and binding agent, the G.B. Corrugated “400” product has appeared in asbestos-related litigation involving National Gypsum and affiliated entities.

Asbestos Content

Corrugated sheet products manufactured during the period when National Gypsum produced the G.B. product line were consistent with industry-wide practice of incorporating asbestos fibers into cement and composite matrices. Chrysotile asbestos — the most commercially prevalent form of the mineral — was routinely used in fiber-cement corrugated products as a reinforcing agent, improving tensile strength, fire resistance, and dimensional stability in the finished sheet.

Litigation records document that plaintiffs alleged the G.B. Corrugated “400” Siding and Roofing Material contained asbestos fibers as a component of its manufacturing composition. The addition of asbestos to corrugated sheet materials was a standard and widely documented practice among building products manufacturers of the period, and regulatory and industrial hygiene records from the twentieth century confirm that such products could release respirable asbestos fibers when cut, drilled, broken, or otherwise mechanically disturbed.

While the precise asbestos content percentage for the G.B. Corrugated “400” is not independently documented in publicly available product specifications, fiber-cement corrugated products of similar construction and era have been identified in asbestos hazard assessments conducted under the Asbestos Hazard Emergency Response Act (AHERA) and related regulatory frameworks as materials capable of releasing asbestos fibers under friable or damaged conditions.

How Workers Were Exposed

Exposure to asbestos fibers from corrugated siding and roofing products occurred primarily during fabrication, installation, maintenance, and removal activities. The corrugated sheet form required on-site cutting and shaping to fit structural dimensions, and these operations — performed with hand saws, power circular saws, and angle grinders — generated dust that litigation records document as a source of asbestos fiber release.

Industrial workers generally represent the trade category most closely associated with documented exposure to the G.B. Corrugated “400” product. Workers employed in manufacturing plants, industrial facilities, refineries, power generation stations, and similar heavy-use environments frequently worked in or near structures clad or roofed with corrugated asbestos-containing sheet materials. Maintenance crews tasked with repairing damaged roofing panels, replacing deteriorated sections, or working overhead in buildings where these materials were installed were at particular risk of inhaling airborne asbestos fibers released during disturbance of the material.

Plaintiffs alleged that cutting and fastening corrugated sheets during original installation generated significant dust exposure for roofing and siding mechanics, carpenters, and laborers working on industrial construction projects. Maintenance workers who drilled fastener holes, broke panels during repair, or swept debris from deteriorating corrugated roofing also alleged occupational exposures through these activities.

Secondary exposure was documented in litigation records involving bystander workers — those employed in adjacent trades or areas who were present when corrugated sheet work was performed but who were not directly handling the material themselves. In large industrial construction environments, bystander exposures represented a recognized pathway given that asbestos-fiber-containing dust could travel considerable distances from active cutting or demolition work.

Deterioration over time also posed a continuing exposure risk. Corrugated roofing and siding materials installed on structures were subject to weathering, impact damage, and mechanical degradation, conditions that could render previously stable asbestos-containing material friable and capable of releasing fibers into occupied work environments. Maintenance personnel, inspectors, and workers stationed inside facilities with aging corrugated roofing have appeared in litigation records as claimants alleging chronic low-level exposures from deteriorating overhead materials.

OSHA’s permissible exposure limits and action levels for asbestos, established and periodically revised in regulations codified at 29 C.F.R. § 1910.1001 and § 1926.1101, reflect the regulatory determination that occupational asbestos exposure presents serious health risks including mesothelioma, asbestosis, and lung cancer — diseases alleged by plaintiffs in litigation involving National Gypsum products.